09.12.22 TAB Agenda 6 DCS Transportation
CITY OF BOULDER
TRANSPORTATION ADVISORY BOARD
AGENDA ITEM
MEETING DATE: September 12, 2022
AGENDA TITLE:
Transportation Standards Update (Phase 2) Recommendation and Public Hearing
PRESENTER(S):
Natalie Stiffler, Interim Director of Transportation and Mobility
Gerrit Slatter, Principal Transportation Projects Engineer
Scott Schlecht, Transportation Maintenance Manager
Edward Stafford, Senior Manager –Planning and Development Services Department
Michael Koslow, Civil Engineering Senior Project Manager
David Thompson, Civil Engineering Senior Project Manager
EXECUTIVE SUMMARY:
This memo provides a summary of the revisions and additions to the ‘Phase 2’ effort of the
transportation infrastructure related portion of the City of Boulder Design and Construction Standards
(DCS) Update. Phase 1 updates, which took place in 2019/2020, provided specific updates to Chapter 2,
with a focus on clarification of standard, buffered and separated bike lane standards such that the DCS
would be consistent with the Low-Stress Walk and Bike Network Plan. Phase 1 also updated the
pedestrian ramp standards in Chapter 11. The Phase 1 update was adopted by City Council in February
2020. The Phase 2 DCS update has been focused on Street Geometric Design Standards, Streetscape and
Landscaping Design and Maintenance Standards and also updates portions of the Sight Triangle section
of the Boulder Revised Code 9-9-7 (BRC) (The BRC are regulations adopted though the legislative
process by the City Council.)
The purpose of the Phase 2 update is to align these sections with recently adopted policy and technical
documents (e.g., Transportation Master Plan, Low-Stress Walk and Bike Network Plan, and internal
Transportation Landscapes Plan) and to ensure that industry best practices are being followed. The DCS
is used to help guide public infrastructure built by both private development and city funded capital
infrastructure and maintenance projects.
The Phase 2 project was initiated in June 2021, with an initial round of community engagement in
September 2021. The 60% level review entailed community and board engagement and feedback
regarding the proposed recommendations. Staff have considered the feedback provided and integrated
additional changes that reflect this input which is now included in this final document of recommended
changes for which TAB recommendation is requested.
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STAFF RECOMMENDATION
Staff recommends TAB consider the following motion:
TAB recommends approval of the proposed revisions to the DCS to the Planning Board and City
Council.
BACKGROUND:
The current DCS was adopted in 1998 and had major updates in 2000 and again in 2020. The DCS
exists to prescribe minimum standards to be used in the design and construction of infrastructure located
in public right-of-way/easements of the city of Boulder, as well as private transportation improvements
that connect to or impact public infrastructure. The DCS is enacted through the BRC, and changes are
adopted by City Council with recommendations from appropriate boards, such as TAB and Planning
Board.
A number of DCS transportation standards have been previously identified for potential update, which
has been based in part upon community feedback received over the years. Additionally, the
Transportation Master Plan Update in September 2019, the Low-Stress Walk and Bike Network Plan in
2019 and completion of the Transportation Landscapes Plan in 2020, along with other transportation
staff work, has highlighted additional items to be updated in the DCS and BRC. The proposed changes
are intended to update relevant standards to current best practices and provide consistency between
adopted master plans and the standards of the DCS.
Additional updates to other transportation related sections of the DCS are anticipated in future years.
The goals of the Phase 2 update are:
- Overall: Modernize the requirements to which facilities are designed and constructed so private
and public projects are consistent in application. This aligns with the departments’ Operational
Excellence guidepost and being more efficient and effective in the delivery of our desired results.
- Street geometric design: Decrease the potential for and/or severity of conflicts between all users
(motorists, bicyclists and pedestrians) by modifying conflict points, reducing the speed of
vehicles at conflict points such as driveways and intersections, and increase visibility between
modes.
- Streetscape, landscaping, and irrigation: Support landscapes that are fiscally maintainable
within city resources and in line with the environmental sustainability goals highlighted in the
Urban Forestry Strategic Plan and the Transportation Landscape Maintenance Plan.
- Sight triangle section in the Boulder Revised Code: further embrace Boulder’s multimodal
system by adding standards related to private land that relate to multi-use paths, increase
visibility between modes at intersections and recognize the built environment’s impact to sight
distance through the placement of buildings.
COMMUNITY ENGAGEMENT:
Community engagement has included targeted outreach to groups that regularly use the DCS and/or that
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have expressed an interest in the update (e.g., the development and engineering community, Community
Cycles Advocacy Committee (CCAC) and TAB), as well as informing and consulting with the
community at large. An online BeHeard Boulder questionnaire was shared in via partners like the
Boulder Chamber of Commerce and on the City’s social media. The team presented to CCAC and to the
Center for People with Disabilities and also held three separate virtual office hours. Highlights of the
recommendations, a summary of community engagement, and working drafts of Chapters 2, 3, and 10
have been provided on the project website. The key areas of input received through the community
engagement process include the following areas:
• Narrower lane widths to slow vehicle traffic (this is included in the update)
• Minimizing the number of left turn lanes to minimize crossing distances (this is included in the
update)
• Support for additional raised crossing details (this is included in the update)
• Support for minimizing corner radii as a method to reduce turning vehicle speeds, as well as a
desire to accommodate larger vehicles, such as transit (this is included in the update)
• Reminder to build facilities that we can maintain (this is indirectly included in the update with
revisions to landscape standards that will allow the city to better maintain installed landscape
areas)
• Concern about excessive signage and markings (this may be addressed in a future update)
• Concern about pedestrians and people with disabilities being able to safely and easily navigate
traffic circles (this may be addressed in a future update)
PROJECT SCOPE:
The scope of the Phase 2 recommendations is focused on street geometric design and streetscape design
and standards, as detailed below.
Street Geometric Design
The intent of the Street Geometric Design (Section 2.07) revisions is to make changes to the standards of
radius of intersections, curb returns, horizontal curves, lane widths, design speed and turning radii for
improved bicyclist and pedestrian safety. The Street Geometric Design section is applicable to city-
funded capital projects such as the North Broadway Reconstruction project currently under construction
and the 30th Street Separated Bike Lanes project which is currently being designed. It is also used on
private development projects when a developer is responsible for implementing infrastructure in the
public right-of-way. An example of this type of project is the Junction Place roadway between Pearl
Parkway and Prairie.
Within Section 2.07 STREET GEOMETRIC DESIGN, the following subsections and tables/figures
were updated:
Section 2.07 STREET GEOMETRIC DESIGN
Topics:
(A) Minimum Requirements
(B) Right-of-Way
(C) Lane Width—UPDATED
(D) Horizontal Alignment—UPDATED
Tables:
Table 2-5: Minimum Street Lane Widths—
UPDATED
Table 2-6: Minimum Horizontal Street Curve
Specifications
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(E) Vertical Alignment
(F) Sight Distance—UPDATED
(G) Medians
(H) Vertical Clearance of Structures
Table 2-6a: Separated Bike Lane Minimum
Horizontal Curve Specifications—NEW
Table 2-7: Minimum Street Spacing
Table 2-8: Minimum Intersection Radii
Table 2-8a: Relationship between Effective and
Actual Radius for the Default Design Vehicle
(SU-30)—NEW
Table 2-9: Maximum Street Grades
Table 2-10: Vertical Curve Design Control
Table 2-11: Separated Bike Lane Intersection
Sight Distance
Table 2-12: Median Width Design Standards
Figures:
Figure 1. Actual and Effective Radius at a
Conventional Intersection Corner—NEW
Figure 2. Actual and Effective Radius at a
Conventional Intersection Corner with a Curb
Extension—NEW
Figure 3. Example of a Mountable Truck
Apron at an Intersection Corner—NEW
Highlights of the specific changes include:
Vehicle Lane Widths Update lane widths table with new, narrower preferred widths for vehicle lanes
to align with current best practice for constructing streets that serve people
walking and bicycling.
Anticipated benefit: Narrower vehicle lane widths typically yield slower
vehicle speeds.
Bicycle Lane Widths Add lane widths for all expected types of bike lanes including conventional,
buffered, separated, and parking-protected.
Anticipated benefit: Providing standard widths for bicycle lanes will lead to
more consistent projects that prioritize bicyclist safety and comfort.
Separated Bike
Lanes
Provide additional technical information about operating speed of bicyclists and
the effect on design features.
Anticipated benefit: Providing more nuanced information about separated bike
lane design will lead to more consistent design of separated bike lanes that are
comfortable for bicyclists of all ages and abilities.
Road Width Tapers
(Bike Lanes)
Add information about bike lane tapers in addition to existing motor vehicle lane
tapers.
Anticipated benefit: Eliminating bike lane designs with abrupt tapers (changes
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in direction) that can cause rider discomfort
Left-Turn Lanes Clarify goal to use a single left-turn lane first, then dual left turns if necessary.
Added statement that double and triple left-turn lanes are only allowed with
Director approval.
Anticipated benefit: Reducing the number of left-turn lanes at intersections
shortens crossing distances for pedestrians and bicyclists.
While the focus of the updates within Chapter 2 is Street Geometric Design (Section 2.07), for
consistency and completeness, other related and incidental updates are also being proposed. For
example, the project team wanted to ensure that the new bike lane widths in Table 2-5 and other related
details are now also reflected in Section 2.11 – Bicycle Facilities and Multi-Use Path Design. In
addition, as new drawings were developed to address other design features (such as traffic circles and
raised pedestrian crossings), staff put the additional related text in a new section (Section 2.14 – Traffic
Calming).
Highlights of the specific changes within Section 2.11 include:
Separated Bike
Lanes at Driveways
Add new figures
Figure 4 - Typical Layout for One-way Street Level Separated Bike Lanes
at Driveways—NEW
Figure 5 - Typical Layout for Sidewalk Level One-way Separated Bike
Lanes at Driveways—NEW
Anticipated benefit: Separated bike lanes typically cross driveways and alleys.
Standardizing this element of design can improve visibility of bicyclists and
improve yielding compliance.
Separated Bike
Lanes at
Intersections
Add new figures
Figure 6 - Typical Layout of Street Level Separated Bike Lanes at
Intersection in Retrofit Conditions—NEW
Figure 7 - Typical Layout of Street Level Separated Bike Lanes at
Intersections in New or Retrofiited Condition—NEW
Figure 8 - Typical Layout of One-way Separated Bike Lane and Right Turn
Lane—NEW
Figure 9 - Typical Layout of One-way Separated Bike Lane and Right Turn
Lane—NEW
Anticipated benefit: The most complex aspect of separated bike lanes is at
intersections. Providing examples of how to maintain safety and good sightlines
through the intersection will lead to consistent design of future projects.
Highlights of the new Section 2.14 include:
Neighborhood
Traffic Circles
Add new figure
Figure 10 – Typical Layout and Standard Dimensions of Neighborhood
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Traffic Circle—NEW
Anticipated benefit: Neighborhood traffic circles are a great traffic calming
technique for local streets. Standardizing their design with typical dimensions
will help provide consistent design of future projects.
Raised Crossings Add new figures
Figure 11 - Typical Layout of Raised Crossing at Mid-Block Location—
NEW
Figure 12 - Typical Layout of Raised Crossing at Intersection Leg Location
- NEW
Figure 11 - Typical Layout of Raised Crossing at Channelized Right Turn
Location —NEW
Anticipated benefit: Standardizing raised crossing design will help provide
consistent traffic calming and yielding compliance benefits.
Streetscape Design and Standards Chapters
The intent of the update to the Streetscape Design and Standards chapters is to consider changes to tree
buffer, irrigation and list of recommended plantings to reflect the Green Infrastructure a Plan for
Transportation Landscapes and other Parks and Recreation and P&DS work efforts. The Streetscape
Design and Standards chapters are used for both city capital project and private development public
transportation infrastructure projects where there are landscape implementation elements. For example,
the Diagonal Reconstruction project constructed in 2016 used Chapter 3 of the DCS as a standard.
Within Chapter 3 and Chapter 10, the following sections and tables/figures were updated:
Chapter 3 STREETSCAPE DESIGN AND TREE LOCATIONS
Topics:
3.01 General—UPDATED
3.02 Landscaping Plan—UPDATED
3.03 Street Trees and Plants—UPDATED
3.04 Tree Removal and Relocation—
UPDATED
3.05 Tree Protection for Construction Sites—
UPDATED
3.06 General Landscaping and Maintenance
Requirements—UPDATED
Tables:
Table 3-1: Approved Street Tree List for Non-
paved Medians and Landscape Planting
Strips—REMOVED
Table 3-2: Limitations on Individual Tree
Species—UPDATED
Table 3-3: Tree Grates and Planting Pits
Standards—UPDATED
Table 3-4: Approved Street Tree List for Paved
Areas Using Tree Grates and Planting Pits—
REMOVED
Table 3-5: Approved Median Shrub List—
REMOVED
Table 3-6: Tree Characteristics—REMOVED
Chapter 10 STREETSCAPE & LANDSCAPE STANDARDS—RENAMED
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Topics:
10.1 General—UPDATED
10.2 Site Preparation—UPDATED
10.3 Planting—UPDATED
10.4 Seeding/Sodding—UPDATED
10.5 Permanent Underground Irrigation
System—RENAMED AND UPDATED
Tables:
Table 10-1: Topsoil Mechanical Analysis
Table 10-2: Minimum Root Ball Sizes—
UPDATED
Table 10-3: Wildflowers—REMOVED
Table 10-4: Grasses—REMOVED
Table 10-5: Soil Amendment Mix Mechanical
Analysis
Technical Drawings (Chapter 11)
Chapter 11 contains technical drawings related to the above sections. The following new drawings were
added:
- Related to Section 2.07:
o 2.07.L Bike Ramp and Pre-Cast Curb Buffer
o 2.07.M Curb Extension Detail
o 2.07.N Curb Extension Cross Sections
o 2.07.O Floating Bus Stop Detail
o 2.07.P Floating Bus Stop Cross Sections
The following existing drawings were updated:
- Related to Section 2.07:
o 2.02.D Multi-Use Path Section Detail
o 2.03 Crosspan and Radii Curb Return Accesses
o 2.42.A Median Paved Curb Skirt
o 2.42.C Median Separated Bike Lane
o 2.51 Bicycle Path Cross-Section
o 2.61.A Non-Residential Street Cross-Section Examples
o 2.61.B Non-Residential Street Cross-Section Examples
- Related to Chapter 3:
o 3.01 Streetscape Tree Spacing and Location Drawing
o 3.03 Tree Grate for Sidewalk Planting Drawing
Boulder Revised Code 9-9-7 Sight Triangles
The intent of the update to the Boulder Revised Code (BRC) is to consider changes to sightlines for
improved safety for all travel modes. The specific section to be revised is 9-9-7.
Highlights of the BRC 9-9-7 Sight Triangles updates include:
15’x15’ Sight
Triangle
Update the location of where the sides of the sight triangle are measured when
the public street has a sidewalk in the existing figure. Currently the sight triangle
is measured along the right-of-way line of the public street and either the right-
of-way line of the public alley or the edge of the private driveway and whose
third side is a line connecting the two sides.
Anticipated benefit: This change will provide staff with physical features to
measure the sides of the sight triangle when responding to sight triangle
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complaints.
Multi-use path
intersecting either an
Alley or Driveway
Add a new figure with a 15’ x 96’ sight triangle. The sides of the new multi-use
path sight triangle would be 15’ x 96’ with the third side of the sight triangle
being the line that connects the two sides.
Anticipated benefit: The 15’ x 15’ sight triangle is currently used where a
multi-use path (path) intersects with either a driveway or alley. The new sight
triangle increases the sight triangle area between the path and either a driveway
or alley.
Timeline
This phase of the update project is expected to extend through Q4 2022, with a public hearing and
recommendation from the Planning Board in October and City Council public hearing and final action in
November/December.
NEXT STEPS:
After the September 2022 TAB meeting and public hearing, staff will present the proposed changes and
TAB’s recommendation to Planning Board for its consideration and recommendation to the City
Council. Planning Board will hold a public hearing in October 2022 and will be asked to make a
recommendation to City Council. The project is scheduled to be presented to City Council for public
hearing and final action in November/December 2022.
ATTACHMENTS
Attachment A - Markup of Chapter 2 DCS Changes
Attachment B - Markup of Chapter 3 DCS Changes
Attachment C - Markup of Chapter 10 DCS Changes
Attachment D - Markup of BRC 9-9-7 Changes
Attachment E – Chapter 11 Drawing Revisions and Additions
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Effective: February 6, 2020TBD DESIGN AND CONSTRUCTION STANDARDS 2-i
CITY OF BOULDER
DESIGN AND CONSTRUCTION STANDARDS
CHAPTER 2
TRANSPORTATION DESIGN
TABLE OF CONTENTS
Section Page
2.01 GENERAL ..................................................................................................................................................... 1
(A) INTENT ............................................................................................................................................................. 1
(B) TRANSPORTATION MASTER PLAN .................................................................................................................... 1
(C) REFERENCE STANDARDS .................................................................................................................................. 1
(D) FUNCTIONAL STREET CLASSIFICATION ............................................................................................................ 1
2.02 TRAFFIC STUDY ........................................................................................................................................ 1
(A) TRAFFIC ASSESSMENT ..................................................................................................................................... 1
(B) TRAFFIC STUDY REQUIREMENTS ..................................................................................................................... 1
(C) RESPONSIBILITIES FOR TRAFFIC STUDIES ......................................................................................................... 1
(D) PREPARATION .................................................................................................................................................. 2
(E) COORDINATION WITH CITY .............................................................................................................................. 2
(F) SUBMITTAL ...................................................................................................................................................... 2
2.03 TRAFFIC STUDY FORMAT ...................................................................................................................... 2
(A) STUDY REQUIREMENTS .................................................................................................................................... 2
(B) INTRODUCTION ................................................................................................................................................ 2
(C) SITE LOCATION AND ZONING ........................................................................................................................... 2
(D) STUDY AREA BOUNDARIES .............................................................................................................................. 2
(E) EXISTING AREA STREET SYSTEM DESCRIPTION ............................................................................................... 2
(F) EXISTING AND PROJECTED ROADWAY AND INTERSECTION TRAFFIC VOLUMES ............................................... 3
(G) EXISTING AND PROPOSED SITE USES ............................................................................................................... 3
(H) EXISTING AND PROPOSED LAND USES IN VICINITY OF THE SITE ...................................................................... 3
(I) TRANSPORTATION DEMAND MANAGEMENT STRATEGIES ................................................................................ 3
(J) TRIP GENERATION ........................................................................................................................................... 3
(K) TRIP DISTRIBUTION/ASSIGNMENT AND MODAL SPLIT ..................................................................................... 4
(L) EXISTING AND PROJECTED TRAFFIC VOLUMES ................................................................................................ 5
(M) TRANSPORTATION SERVICE STANDARDS ......................................................................................................... 6
(N) LEVEL OF SERVICE ANALYSIS .......................................................................................................................... 7
(O) TRAFFIC COUNTS AND ANALYSES WORKSHEETS ............................................................................................. 7
(P) TRAFFIC CONTROL AND SIGNALS .................................................................................................................... 7
(Q) TRAFFIC CRASHES............................................................................................................................................ 8
(R) NOISE ATTENUATION ....................................................................................................................................... 8
(S) RECOMMENDATIONS ........................................................................................................................................ 8
(T) CONCLUSION .................................................................................................................................................... 9
(U) REVISIONS TO TRAFFIC STUDY ........................................................................................................................ 9
2.04 SITE ACCESS ............................................................................................................................................. 10
(A) ACCESS REQUIREMENTS ................................................................................................................................ 10
(B) ACCESS PERMIT REQUIRED ............................................................................................................................ 10
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2-ii DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
(C) LOCATION OF ACCESS .................................................................................................................................... 10
(D) SIGHT DISTANCE ............................................................................................................................................ 11
(E) RESTRICTION OF TURNING MOVEMENTS ....................................................................................................... 11
(F) TRAFFIC CONTROL ......................................................................................................................................... 11
(G) ONE-WAY ACCESS LANES ............................................................................................................................. 11
(H) SPEED CHANGE LANES .................................................................................................................................. 12
(I) ACCESS AND CURB CUT TYPE ........................................................................................................................ 12
(J) ACCESS AND CURB CUT WIDTH ..................................................................................................................... 13
(K) ACCESS AND CURB CUT RADII ....................................................................................................................... 13
(L) ACCESS AND CURB CUT GRADES ................................................................................................................... 13
(M) DRIVEWAYS ................................................................................................................................................... 13
2.05 RIGHT-OF-WAY REQUIREMENTS ...................................................................................................... 14
2.06 BASE STREET AND ALLEY STANDARDS .......................................................................................... 14
(A) BASE STREET STANDARD ............................................................................................................................... 14
(B) BASE ALLEY STANDARD ............................................................................................................................ 1514
2.07 STREET GEOMETRIC DESIGN ............................................................................................................. 15
(A) MINIMUM REQUIREMENTS ............................................................................................................................. 15
(B) RIGHT-OF-WAY ............................................................................................................................................. 15
(C) LANE WIDTH .................................................................................................................................................. 16
(D) HORIZONTAL ALIGNMENT ......................................................................................................................... 1816
(E) VERTICAL ALIGNMENT .............................................................................................................................. 2519
(F) SIGHT DISTANCE ........................................................................................................................................ 2519
(G) MEDIANS ................................................................................................................................................... 2619
(H) VERTICAL CLEARANCE OF STRUCTURES .................................................................................................... 2720
2.08 SIDEWALKS ........................................................................................................................................... 2720
(A) REQUIRED .................................................................................................................................................. 2720
(B) CONFORMANCE WITH THE TRANSPORTATION MASTER PLAN .................................................................... 2720
(C) COMPLIANCE WITH AMERICANS WITH DISABILITIES ACT (ADA) .............................................................. 2720
(D) MINIMUM WIDTHS ..................................................................................................................................... 2720
(E) VERTICAL GRADES .................................................................................................................................... 2721
(F) VERTICAL CLEARANCE .............................................................................................................................. 2821
2.09 RESIDENTIAL STREETS .................................................................................................................... 2821
(A) PURPOSE .................................................................................................................................................... 2821
(B) SCOPE ........................................................................................................................................................ 2821
(C) DIRECTOR REVIEW ..................................................................................................................................... 2922
(D) RESIDENTIAL STREET SECTIONS ................................................................................................................ 3023
2.10 EMERGENCY ACCESS LANES .......................................................................................................... 3528
(A) EMERGENCY ACCESS REQUIRED ................................................................................................................ 3528
(B) WHEN EMERGENCY ACCESS LANE IS REQUIRED ....................................................................................... 3528
(C) SECONDARY EMERGENCY ACCESS ............................................................................................................ 3629
(D) LOCAL EMERGENCY ACCESS LANE STANDARDS ....................................................................................... 3629
(E) UNOBSTRUCTED ACCESS ........................................................................................................................... 3629
(F) ACCESS IDENTIFICATION ............................................................................................................................ 3629
2.11 BICYCLE FACILITIES AND MULTI-USE PATH DESIGN ........................................................... 3730
(A) CONFORMANCE WITH BICYCLE SYSTEM PLAN........................................................................................... 3730
(B) ON-STREET BIKE LANES - STREETS WITHOUT ON-STREET PARKING ........................................................ 3730
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Effective: February 6, 2020TBD DESIGN AND CONSTRUCTION STANDARDS 2-iii
(C) ON-STREET BIKE LANES - STREETS WITH ON-STREET PARKING ............................................................... 3730
(D) BUFFERED BIKE LANES ............................................................................................................................... 3730
(E) SEPARATED BIKE LANES (PROTECTED BIKE LANES OR CYCLE TRACKS - ONE-WAY AND TWO-WAY) ....... 3730
(F) OFF-STREET BIKE PATHS OR TRAILS ......................................................................................................... 4231
(G) BICYCLE PARKING ..................................................................................................................................... 4331
2.12 STREET LIGHTING.............................................................................................................................. 4533
(A) SCOPE ........................................................................................................................................................ 4533
(B) GUIDELINES FOR STREET LIGHTING ........................................................................................................... 4533
(C) EASEMENTS ............................................................................................................................................... 4634
2.13 TRANSIT FACILITIES ............................................................................................................................... 4634
(A) TRANSIT STOP DESIGN ......................................................................... ERROR! BOOKMARK NOT DEFINED.34
LIST OF TABLES
Number Page
TABLE 2-1: ACCESS SPACING REQUIREMENTS ............................................................................................................ 10
TABLE 2-2: ACCESS DESIGN SPECIFICATIONS ............................................................................................................. 12
TABLE 2-3: BASE STREET STANDARD COMPONENTS ................................................................................................... 15
TABLE 2-4: BASE ALLEY STANDARD COMPONENTS .................................................................................................... 15
TABLE 2-5: MINIMUM STREET LANE WIDTHS .................................................... ERROR! BOOKMARK NOT DEFINED.16
TABLE 2-6: MINIMUM HORIZONTAL STREET CURVE SPECIFICATIONS ..................................................................... 1816
TABLE 2-7: MINIMUM STREET SPACING ................................................................................................................... 1917
TABLE 2-8: MINIMUM INTERSECTION RADII ...................................................... ERROR! BOOKMARK NOT DEFINED.17
TABLE 2-9: MAXIMUM STREET GRADES .................................................................................................................. 2519
TABLE 2-10: VERTICAL CURVE DESIGN CONTROL ................................................................................................... 2519
TABLE 2-11: MEDIAN WIDTH DESIGN STANDARDS ................................................................................................. 2620
TABLE 2-12: MINIMUM SIDEWALK WIDTHS ............................................................................................................. 2720
TABLE 2-13: RESIDENTIAL STREET DESIGN STANDARDS ........................................................................................ 3225
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Effective: February 6, 2020TBD DESIGN AND CONSTRUCTION STANDARDS 2-1
2.01 General
(A) Intent
The Transportation Design Standards are intended to provide for an integrated transportation
system for all transportation modes, including pedestrian, bicycle, transit, and motor vehicle.
(B) Transportation Master Plan
All improvements proposed to the City’s transportation system shall conform with the goals , and
policies, and standards adopted in the Transportation Master Plan (TMP).
(C) Reference Standards
Where not specified in these Standards or the B.R.C. 1981, to protect the public health, safety,
and welfare, the Director of Public Works will specify the standards to be applied to the design
and construction of transportation improvements and may refer to one or more of the references
listed in the References Section of these Standards.
(D) Functional Street Classification
Public streets shall be designed and improved to conform to the applicable functional street
classification as defined on the “Street Function Class and Proposed Street Facilities” map of the
TMP.
2.02 Traffic Study
(A) Traffic Assessment
The Director will require an applicant to submit a Traffic Assessment in order to adequately
assess the impacts of any development proposal on the existing and planned transportation
system. The Assessment shall include a peak hour trip generation study projection (Refer to
2.03(J)) and may require additional information as determined by the Director.
(B) Traffic Study Requirements
For any development proposal where trip generation from the development during the peak hour
of the adjacent street is expected to exceed 100 vehicles for nonresidential applications, or 20
vehicles for residential applications the Director will require an applicant to submit a Traffic
Study to evaluate the traffic impacts of the development proposal. The Traffic Study may include
the information required in Subsections (A) through (K), of Section 2.03, “Traffic Study Format,”
of these Standards at the discretion of the Director.
(C) Responsibilities for Traffic Studies
An applicant for construction approval shall be responsible for assessing all traffic impacts
associated with a proposed development, with the City serving in a review and approval capacity.
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2-2 DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
(D) Preparation
A Traffic Study shall be prepared by an Engineer with adequate experience and expertise in
transportation engineering. The Engineer shall be identified in the Traffic Study.
(E) Coordination with City
Transportation consultants and Engineers preparing Traffic Studies shall discuss proposed
development projects with the Director prior to initiating the study. Issues to be discussed
include, without limitation, the TMP, definition of the study area, relevant subarea, area, and
subcommunity plans, methods for projecting build-out volumes, background traffic conditions,
trip generation, directional distribution of traffic, and trip assignment. These aspects of the
Traffic Study shall be approved by the Director prior to study preparation.
(F) Submittal
A Traffic Study shall be prepared in conformance with, and including, the information required in
Section 2.03, “Traffic Study Format,” of these Standards.
2.03 Traffic Study Format
(A) Study Requirements
The information provided in the Traffic Study shall include the following sections as outlined
below. The study shall be typed and bound, and clearly identify the data and information in the
appropriate sections. In addition, the study shall contain a table of contents, lists of figures, and
tables, and shall identify any map pockets and included drawings.
(B) Introduction
The Traffic Study shall provide an introduction with an overview and discussion of the project or
development proposal.
(C) Site Location and Zoning
Include a vicinity map detailing the property location, a conceptual site plan reflecting the
boundaries of the project or development, and information detailing the designated zoning
district, general terrain and physical features of the site and the surrounding area.
(D) Study Area Boundaries
Include the Study Area Boundaries as determined based on discussions with the Director and
include all roadways and transportation routes providing access to the site and the surrounding
transportation system.
(E) Existing Area Street System Description
Describe and include roadway orientations, functional classifications and geometries, intersection
geometries, and traffic controls, including without limitation signage and striping, speed limits,
parking restrictions, sight distance, transit routes, the presence of bicycle and pedestrian facilities,
and any other related traffic operations information and improvements approved or planned by
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government agencies. For identified improvements scheduled by government agencies, include
the nature of the improvements, extent, implementation schedule, and the agency or funding
source responsible.
(F) Existing and Projected Roadway and Intersection Traffic Volumes
Include diagrams that map existing traffic volumes, and each variation of projected traffic
volumes, for all roadways and intersections within the study area. Also provide diagrams that
map the intersection and roadway geometries and traffic control within the study area.
(G) Existing and Proposed Site Uses
Include an identification of the existing land use and proposed land use or the highest potential
land use based on zoning and maximum trip generation where a specific use has not been
determined. If rezoning is proposed, the study shall provide a comparison between the highest trip
generation uses for the existing zoning and the highest trip generation uses for the proposed
zoning.
(H) Existing and Proposed Land Uses in Vicinity of the Site
Document any vacant land or potential redevelopment that may result in a change in traffic
volume conditions within the study area during each time period studied. Perform and provide
trip generation on these parcels and include the trips generated from these parcels in the trip
volume diagrams and level of service analyses for each appropriate time period studied.
(I) Transportation Demand Management Strategies
Include an outline of transportation demand management strategies to mitigate traffic impacts
created by proposed development and implementable measures for promoting alternate modes of
travel, including but not limited to the following:
(1) Site Design: Incorporate design features that facilitate walking, biking, and use of transit
services to access a proposed development, including features such as transit shelters and
benches, site amenities, site design layouts, orientations and connections to increase
convenience for alternate modes and reduce multiple trips to and from the site, and direct
connections to existing offsite pedestrian, bicycle, and transit systems.
(2) Programs and Education: Incorporate alternate modes programs, such as providing
transit passes to employees and residents, van pooling to the site by a major employer,
ride-sharing, parking pricing, and planned delivery services, and educational measures
such, as promoting telecommuting, distributing transit schedules and trails maps, signing
alternate travel routes, and providing an onsite transportation coordinator or plan to
educate and assist residents, employees, and customers in using alternate modes.
(J) Trip Generation
Traffic estimates for the proposed project and potential developed or redeveloped properties in
the study area shall be obtained by performing trip generation using the procedures outlined in the
most current edition of the Trip Generation Manual of the Institute of Transportation Engineers
(ITE). If adequate Trip Generation Manual data is not available for a specific land use, the
procedures used to estimate trip generation data shall be approved by the Director. Include the
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following specific trip generation information:
(1) Summary Table: List each land use that requires trip generation analysis, including the
project plus developed or redeveloped land uses within the study area. For each trip
generation summary include land use type, amount, intensity, average trip generation
rates for total daily traffic and peak hour traffic (a.m., noon and/or p.m. peak hour traffic
generation may be required), and the resultant total trips generated for each time period
and each land use.
(2) Calculations: Calculation of projected trip generation for any land use, used to
determine study area impacts, shall be based on the following:
(a) Trip generation formulas (or rates, if formulas are not available) published in the
most recent version of the Trip Generation Manual. Trip generation reports from
other industry publications may be considered but are subject to the approval of
the Director.
(b) A local trip generation study, following procedures outlined in the most recent
version of the Trip Generation Manual, if no published rates are available and
similar land uses can be studied.
(c) Additional data or studies from other similar jurisdictions. Trip generation
obtained in this fashion is subject to the review and approval of the Director.
(3) Trip Generation Reductions: Credit for any trip reductions is subject to review and
approval in advance by the Director. Anticipated trip reduction assumptions should be
discussed and approved by the Director prior to the preparation of the Traffic Study. Trip
reductions typically fall into one of two categories: those that reassign some portion of
the trip generation from the surrounding roadway network (passerby and diverted trip
reductions), and those that remove trips generated from the land use trip generation
(internal and modal split reductions).
(a) Use of passerby and diverted trip reductions may be evaluated and considered in
reducing the additional estimated total trip generation of a new land use.
However, passerby and diverted trip reduction factors are not to be applied
directly to reduce trip generation and turning movement volumes at driveways
serving the studied land use. These factors are subject to the approval of the
Director.
(b) Internal trip reductions and modal split assumptions may reduce the total trip
generation of a land use. These factors considered in the Traffic Study shall
supply analytical support and detailed documentation to demonstrate how the
estimates were derived and incorporated, and are subject to the approval of the
Director.
(K) Trip Distribution/Assignment and Modal Split
Trip distribution/assignment of any generated traffic estimates shall be clearly summarized and
illustrated for each access route entering and exiting the generating land use, using the study area
transportation system as a basis. Include the following specific trip distribution/assignment
information:
(1) Trip Distribution: The trip distribution for each site shall be identified and illustrated
with a graphical figure detailing the percentages making each movement, at each
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intersection in the study area. The trip distribution shall be logically based upon factors
such as the site’s location within the City’s existing traffic volume data in the study area,
market analyses, applied census data, and/or professional engineering judgment. Trip
distribution assumptions are subject to the approval of the Director.
(2) Trip Assignment: Trip assignment shall be done by applying the trip generation totals
for each time period studied, to the trip distribution percentages developed. The trip
assignment shall develop anticipated traffic volumes for each of the movements
identified by the trip distribution and each of the time periods identified in the analyses.
The resulting traffic volumes shall be illustrated with graphical figures detailing the
anticipated volumes making each movement, at each intersection in the study area, during
each time period studied.
(L) Existing and Projected Traffic Volumes
(1) Traffic Volume Scenarios: Five traffic volume scenarios and three separate times of the
day may be required to be included in a Traffic Study analysis. The applicant shall meet
with the Director to determine the scenarios and time periods to be studied, prior to the
development of the Traffic Study. The number of scenarios and time periods to be
studied are subject to the approval of the Director. The potential scenarios and time
periods include the following:
(a) Scenario 1 - Existing Conditions: An analysis of existing traffic conditions will
be required in the Traffic Study. Existing Conditions analysis should attempt to
model traffic conditions at the time the Traffic Study is being prepared. Traffic
counts that are older than the year the study is being prepared shall be factored up
or adjusted to existing year volumes.
(b) Scenario 2 - Anticipated Project Completion Year Without Project Volumes:
Include an analysis of the anticipated traffic conditions during the year the
project is intended to be finished and traffic is generated. The analysis shall
anticipate the increase in background traffic volumes and the generation of other
related projects that are not present in the existing condition, but would likely be
completed and generating trips in this time period. The trip generation for the
proposed project shall not be included in this scenario. If the project is intended
to be completed the same year that the Traffic Study is being prepared, then this
scenario is the same as Scenario 1 - Existing Conditions.
(c) Scenario 3 - Anticipated Project Completion Year With Project Volumes: This
scenario is the same as Scenario 2, except that the project volumes are assigned
to the roadway network and included in the analyses.
(d) Scenario 4 - Future Buildout Conditions Without Project Volumes: An analysis
of the anticipated traffic conditions during buildout, using the projected buildout
year defined in the City’s TMP. The analysis shall anticipate the increase in
background traffic volumes and the generation of other related projects that are
not present in the existing condition, but would likely be completed and
generating trips in this time period. The trip generation for the proposed project
should not be included in this scenario.
(e) Scenario 5 - Future Buildout Conditions With Project Volumes: This scenario is
the same as Scenario 4, except that the project volumes are assigned to the
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roadway network and included in the analyses.
(2) Traffic Volume Projections: The traffic volume projections shall identify existing and
projected daily traffic counts and peak hour turning movement counts for each access
point, intersection and street identified in the Traffic Study area for each of the
aforementioned scenarios required in the study.
(3) Time Periods: Each scenario may be required to look at three different time periods (the
a.m., noon and p.m. peak hour conditions). The Director will determine which time
periods and scenarios are required for each Traffic Study depending upon the project’s
size, location, types of land uses and other pertinent factors.
(4) Raw Traffic Count Data: Include all raw traffic-count data for average daily and peak
hour conditions and traffic analysis worksheets in the appendices of the Traffic Study for
reference. Computer techniques and associated printouts may be used for this part of the
report.
NOTE: All total daily traffic counts must be actual machine counts, not based on
factored peak hour sampling. Latest available machine counts from the City, and other
agencies, may be acceptable if not more than 2 years older than the year the Traffic Study
is being prepared. Data older than the year the Traffic Study is being prepared shall be
factored up to current year numbers, using growth rates approved by the Director.
(M) Transportation Service Standards
Include a discussion and analysis assessing the impacts of the project or development proposal on
the existing and planned transportation system in the study area with respect to the following
traffic impact and mitigation objectives:
(1) Transportation Master Plan Objectives: TMP service standards’ objectives include the
following:
(a) No long-term growth in auto traffic over current levels described as a 0 percent
increase in vehicle miles traveled.
(b) Reduction in single-occupant vehicle travel to 25 percent of total trips.
(c) Continuous reduction in mobile source emission of air pollutants, and no more
than 20 percent of roadways congested at LOS F.
(2) Level of Service Design Guide: LOS standards objectives include:
(a) Minimum LOS D design guide for peak hour conditions for all movements.
Project impacts that maintain LOS D or better for all intersections and street
segments may not be required to provide LOS-related traffic mitigation
improvements.
(b) LOS E and lower peak hour conditions require the implementation of one or
more transportation management strategies consistent with the goals and
objectives of the TMP. A transportation management strategy plan required to
address and mitigate these conditions may include travel demand management,
land use intensity reduction, site design, layout and access modifications, parking
reduction measures, or transportation infrastructure improvements.
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(N) Level of Service Analysis
(1) The Traffic Study shall provide LOS analyses for all study area intersections (signalized
and unsignalized) and mid-block roadway segments using methodologies outlined in the
current Highway Capacity Manual. The analyses should be performed for Scenarios 1
through 5, described in Section 2.0 3(L), “Existing and Projected Traffic Volumes,” and
for each time period (a.m., noon and/or p.m. peaks) that is required in the Traffic Study,
unless otherwise required by the Director.
(2) Level of service analyses shall consider the appropriate infrastructure, lane usage, traffic
control and any other pertinent factors for each scenario to be studied. Intersections with
planned improvements, discussed in City planning documents, may have those
improvements shown in the level of service analyses.
(3) Signalized intersection level of service analyses shall use the existing timing and phasing
of the intersections for all scenarios. If the analyses are to deviate from existing timings
or phasing, then a detailed signal progression analyses for the affected corridor shall also
be provided.
(4) The results of the level of service analyses for each scenario and each time period shall be
summarized into one or more tables that illustrate the differences in level of service for
each scenario. At a minimum, these tables shall list the level of service results for each
intersection to include the level of service for each approach and the total intersection
level of service, as well as the appropriate delay values for each approach and the total
intersection. These tables shall highlight any locations where the addition of project
traffic has caused any approach of any intersection to fall below the LOS D standard for
the City.
(O) Traffic Counts and Analyses Worksheets
Provide capacity analysis calculations based on the planning or operational analysis techniques
contained in the current Highway Capacity Manual or subsequent highway capacity techniques
established by the Federal Highway Administration, including the following:
(1) Raw Traffic Count Data: Include all raw traffic count data for average daily, hourly
Average daily trip (ADT), and peak hour conditions and traffic analysis worksheets in the
appendices of the Traffic Study for reference. Computer techniques and associated
printouts may be used for this part of the report.
(2) Level of Service Analyses: Include all level of service analyses performed for
intersections and roadway links. If signal timing or phasing changes are proposed for
traffic mitigation and the signal is currently part of a coordinated system, a progression
analysis will be required to ensure that adequate progression is maintained or provided.
All progress analysis and assumptions to be used shall be reviewed and approved by the
Director.
(P) Traffic Control and Signals
The Traffic Study shall discuss and analyze any traffic control measures that may be necessary to
serve a proposed project or development. Any traffic control measures are to be evaluated based
on the requirements established in the Manual on Uniform Traffic Control Devices (MUTCD)
and by the City, and will be applied as necessary to ensure safe and efficient operation of the
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City’s transportation system. The analysis shall demonstrate the need for traffic control measures
considering the objectives and policies of the TMP and alternative site designs in order to
minimize or mitigate traffic impacts from the proposed project or development. The following
traffic control measures are to be addressed:
(1) Regulatory Signage, Markings and Islands: These traffic control measures shall be
applied as necessary in conformance with the MUTCD and City standards and policies.
(2) Traffic Signals: The installation of new traffic signals is not encouraged by the City and
all possible alternatives to signalization shall be evaluated before the installation of a new
traffic signal will be considered. The need for new traffic signals will be based on
warrants contained in the MUTCD and on City policies. In determining the location of a
new signal, safety and community traffic circulation and progression will be the primary
considerations. If a traffic signal is suggested as part of a mitigation package, and the
intersection lies within a series of coordinated traffic signals, then a progression analysis
may be required to ensure that adequate progression may still be provided. Generally, a
spacing of one-half mile between all signalized intersections is to be maintained, to
achieve optimum capacity and signal progression. Pedestrian and bicycle movements
shall be considered in all cases and adequate pedestrian clearance is to be provided in the
signalization design.
(3) Intersection and Access Locations: To provide flexibility and safety for the existing
roadway system and to ensure optimum two-way signal progression, an approved traffic
engineering analysis shall be made to properly locate all proposed intersections that may
require signalization, and any accesses to the proposed development.
(Q) Traffic Crashes
The Traffic Study may need to include crash analyses at one or more locations in the study area.
The Director shall specify whether such crash analyses are needed for each Traffic Study. Where
required, estimates of increased or decreased crash potential shall be evaluated for the proposed
project or development and appropriate safety related mitigation measures are to be included.
Traffic crash data is available through the Sate Streets Report and from the City of Boulder’s
Police Department or from the Director.
(R) Noise Attenuation
If residential development is planned adjacent to a roadway designated collector or greater, the
City may require noise attenuation measures. A discussion and analysis of noise attenuation
measured using the methods in the Fundamentals and Abatement of Highway Traffic Noise
Textbook is to be included in all traffic studies for residential developments adjacent to roadways
designated collector or greater.
(S) Recommendations
(1) The Traffic Study shall include a section in the report that provides any recommendations
of the Engineer. These recommendations shall include the Engineer’s recommended
location, nature and extent of proposed transportation improvements associated with the
project or development to ensure safe and efficient roadway operations and capacity, and
compatibility with the City's transportation system and the goals of the TMP.
(2) These recommendations are to be supported with appropriate documentation and
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discussion of the technical analyses, assumptions and evaluations used to make the
determinations and findings applied in the Traffic Study. In the event that any Traffic
Study analyses or recommendations indicate unsatisfactory levels of service on any study
area roadways, a further description of proposed improvements or mitigation measures to
remedy deficiencies shall be included.
(3) These proposed improvements or mitigation measures may include projects by the City
or The Colorado Department of Transportation for which funds have been appropriated
and obligated. These proposals may also include improvements to be funded and
constructed by the applicant as part of project or development construction. Assumptions
regarding future roads, widths and lane usages in any analyses are subject to the approval
of the Director.
(4) In general, the recommendation section shall include:
(a) Proposed and Recommended Improvements: Provide a detailed description and
sketch of all proposed and recommended improvements. Include basic design
details showing the length, width and other pertinent geometric features of any
proposed improvements. Discuss and abalyzeanalyze whether speed
chagechange lanes are necessary to serve a project of development adjacent to a
collector or arterial street. Discuss whether these improvements are necessary
because of development traffic or whether they would be necessary due to
background traffic. Specify the approximate timing necessary for each
improvement.
(b) Level of Service Analysis at Critical Points: Provide another iteration of the LOS
analyses that demonstrate the anticipated results of making recommended
improvements, such as movement LOS, operational and safety conditions, and
conformance with the City's transportation system goals and TMP. In
association with LOS analyses for recommended improvements, include a
comparison of these results with the background LOS analyses without the
proposed project or development. Where appropriate, this step is to be provided
for both near term (year of project completion) and buildout scenarios.
(T) Conclusion
Include a conclusion in the report that provides a clear and concise description of the study
findings and recommendations, and serves as an executive summary.
(U) Revisions to Traffic Study
(1) Following City review, the Director may require revisions to a Traffic Study based on
the following considerations:
(a) Completeness of the study,
(b) Thoroughness of the level of service and impact analyses and evaluations,
(c) Compatibility of the study with the proposed access design, project or
development plan and local transportation system,
(d) Compliance with local and state regulations and design standards, and
(e) An analysis of study deficiencies, errors, or conflicts.
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(2) Revisions may also be required as a result of public process with surrounding
neighborhoods and land uses or review by City Council or the Planning Board as needed
to demonstrate compliance with these Standards. Additional details requiring Traffic
Study revisions may include, but are not limited to, the following:
(a) An enlarged study area
(b) Alternative trip generation scenarios
(c) Additional level of service analyses
(d) Site planning and design issues.
2.04 Site Access
(A) Access Requirements
All accesses and curb cuts shall be designed and constructed in compliance with these Standards
and the requirements set forth in Section 9-9-5, “Site Access Control,” B.R.C. 1981.
(B) Access Permit Required
All accesses and curb cuts proposed and constructed on City streets and alleys require a permit, as
set forth in Section 9-9-5, “Site Access Control,” B.R.C. 1981.
(C) Location of Access
(1) Spacing: Table 2-1, “Access Spacing Requirements,” shows the required spacing of
access points and curb cuts. Minimum spacing from corners shall be measured from point of
intersection of the street flowlines (front face of curbs). Minimum spacing between accesses
shall be measured at the property line.
Table 2-1: Access Spacing Requirements
Minimum Spacing (measured
from edge of access)
Single Family
Residential
Other Residential Commercial Industrial
Local Streets
- from property line 7.5' 10' 10' 10'
- from corner 20' 50' 50' 50'
- between accesses 15' 20' 20' 20'
Collector Streets Permitted only when no
other access is available.
- from property line 10' 10' 10'
- from corner 50' 50' 50'
- between accesses 20' 20' 20'
Arterial Streets Permitted only when no
other access is available.
- from property line 75' 75' 75'
- from corner 150' 150' 150'
- between accesses 250' 250' 250'
(2) Alignment: Accesses shall intersect City streets at a 90-degree angle. Accesses to
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properties on opposite sides of a collector or arterial, where turning movements are not
controlled by a center median or access island, shall either be aligned, or offset by at least
150 feet on collectors, or at least 300 feet on arterials. Greater offsets may be required if
left-turn storage lanes are required.
(3) Relocation of Existing Access Points and Curb Cuts: Relocation, alteration, or
reconstruction of any existing access points and curb cuts shall meet the requirements of
these Standards.
(D) Sight Distance
All access points and curb cuts shall provide adequate sight distance as set forth under Section
9-9-7, “Sight Triangles,” B.R.C. 1981.
(E) Restriction of Turning Movements
Along streets designated arterial or greater, or where necessary for the safe and efficient
movement of traffic, the City will require access points and curb cuts to provide for only limited
turning movements, as follows:
(1) Access With Barrier Island - Left-Turn Restrictions (“Pork Chop”): Where restricted
turning movements are required by the City, and where the abutting street does not have a
median, a barrier island will be required.
(a) Islands shall have a minimum area of 150 square feet, be bounded by vertical
curb, and have an appropriate concrete center surface treatment, approved by the
Director.
(b) Barrier island lanes shall be at least 12 feet wide, have a radius of at least 20 feet,
and be designed to accommodate the largest vehicle using the access on a daily
basis. The island shall provide congruent curb ramps or cut through for
sidewalks. The pedestrian crossing over the barrier island shall be raised. The
dimensions of a raised crossing shall be designed considering standards for
accessible design and site conditions, including topography, stormwater flow,
and location of utilities. The minimum width of the island along the abutting
roadway frontage shall be 30 feet for right-in, right-out only islands, and 15 feet
for islands allowing right-in, right-out and left-turning movements.
(2) Access With Median Divider Barriers – Left-Turn Restrictions: Median barriers may
be permitted where a median design can improve traffic circulation and safety, or overall
site access. Where permitted, medians shall be at least 4 feet wide, and shall extend at
least 25 feet beyond the right-of-way.
(F) Traffic Control
All accesses shall be designed and constructed with appropriate traffic control and signage
conforming to the MUTCD, B.R.C. 1981, and these Standards.
(G) One-Way Access Lanes
One-way access lanes may be permitted where restricted access is limited to one turning
movement, or where the one-way access improves traffic circulation and safety. One-way access
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lanes shall be at least 12 feet wide, have at least radius of 20 feet, and be designed to
accommodate the largest vehicle using the access on a daily basis.
(H) Speed Change Lanes
Speed change lanes shall be required on Colorado state highways as designated in the Colorado
State Highway Access Code in accordance with the standards of Section 4.8 of the Colorado
State Highway Access Code. For all collectors or arterials that are not Colorado state highways,
the Traffic Study shall make recommendations on the need for speed change lanes, based on the
criteria contained in the Colorado State Highway Access Code. When required by the Director
based on the criteria in the Colorado State Highway Access Code, design of speed change lanes
shall conform with Subsection 2.07(D), "Horizontal Alignment," of these Standards.
(I) Access and Curb Cut Type
(1) Driveway Ramp and Curb Cut: All new accesses and curb cuts shall be designed as
driveway ramps and curb cuts, using the standard ramp driveway details provided in
Chapter 11, except as allowed in Subsection (2), along streets where no curb and gutter
exists, or for single family lots where roll-over curbs have been provided.
(2) Radii Curb Returns: Radii curb return accesses may be required or permitted by the
Director under the following conditions:
(a) The access is located along an arterial or collector.
(b) Access volumes indicate a need for a radii curb return where the ADT exceeds
500 or where speed change lanes would be required.
(c) The access is designed to restrict turning movements, requiring the installation of
an access island or center median.
(d) The roadway has no curb and gutter.
(e) The access serves an industrial property, or provides for commercial deliveries,
where large truck movements are required.
(f) The Director determines that a radii access is necessary to ensure adequate traffic
safety and operation.
(g) The access is for a new public street
Table 2-2: Access Design Specifications
Single Family Other Commercial Industrial
Residential Residential
Width (in feet )
- Minimum 10 10 15 20
- Maximum 20 35 35 35
- One-Way Lane N/A 12-18 12-20 14-24
Radii (in feet)
- Minimum N/A 15 15 20
- Maximum N/A 30 30 40
Access Grades
Initial Grade (to a point 10
ft beyond ROW)
- Minimum (+) 3% (+) 1% (+) 1% (+) 1%
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- Maximum (+) 8% (+) 6% (+) 6% (+) 6%
Final Grade (G2)
- Minimum (+/-) 3% (+/-) 1% (+/-) 1% (+/-) 1%
- Maximum (+/-) 14% (+/-) 8% (+/-) 8% (+/-) 8%
Max Grade Break (+/-) 10% (+/-) 6% (+/-) 6% (+/-) 6%
(J) Access and Curb Cut Width
Access and curb cut widths shall be consistent with Table 2-2, "Access Design Specifications," of
these Standards. Access design for Colorado state highways shall conform to the Colorado State
Highway Access Code. All other access widths shall be determined using turning templates, as
designated by the Director, for a 10 MPH design speed for the largest vehicle expected to use the
access on a daily or routine basis. The width of each access shall be the minimum width that is
necessary to serve the property and use. No more than 50 percent of the street frontage shall be
occupied by the access driveway, except for access to a cul-de-sac or flag lot. All access widths
are measured from edge of pavement to edge of pavement (or curb to curb) at the throat of the
driveway (or edge of the right-of-way), and are not inclusive of drive cut transitions or curb
return radii.
(K) Access and Curb Cut Radii
Access and curb cut radii shall meet the specifications shown in Table 2-2, “Access Design
Specifications,” of these Standards. All radii are measured from the flowline (front face of the
curb) or from the edge of the pavement where no flowline exists.
(L) Access and Curb Cut Grades
Access and curb cut grades shall be consistent with Table 2-2. The initial grade (G1) shall be a
positive grade, beginning at the back of the sidewalk, the back of the driveway ramp or pan
section, or the edge of the pavement (where no curb and gutter exists), and shall continue at least
10 feet beyond the right-of-way. The final grade (G2) may be positive or negative, depending on
the access conditions. The maximum grade break (or change in slope) shall apply at all grade
changes. Additional grade changes may occur at intervals of at least 20 feet.
(M) Driveways
(1) Vehicle Storage: Adequate driveway storage capacity for both inbound and outbound
vehicles to facilitate safe, unobstructed, and efficient traffic circulation and movements
from the adjacent roadway and within the development shall be provided, except for
single-family or duplex residential driveways on local streets. Adequate driveway length
will be subject to approval by the Director and shall extend at least 24 feet beyond the
right-of-way before accessing the first off-street parking space or parking lot aisle.
(2) Internal Circulation: Developments requiring off-street parking facilities shall provide
onsite vehicular circulation allowing access to all portions of the site without using the
adjacent street system, unless a joint access or parking easement with one or more of the
adjacent property owners has been dedicated.
(3) Backing Into the Right-of-Way Prohibited: Driveways shall be designed to contain all
vehicle backing movements onsite, except for single family or duplex residential uses on
local streets.
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(4) Minimum Back-Up Distance for Detached Single-Family Residential Driveways
Accessing Public Alleys: Driveways shall provide for a minimum distance of 24-feet
from the rear of the parking stall or face of garage to the far edge of the adjacent alley
right-of-way or turn around area as required by Chapter 9-9-6, “Parking Standards,”
B.R.C. 1981.
(5) Shared Driveways (Detached Single-Family Residential Only): Shared driveways to
access detached single-family residential lots may be permitted pursuant to an approved
site review or subdivision as set forth in Chapter 9-9-14, “Site Review,” B.R.C. 1981 or
Chapter 9-12, "Subdivision," B.R.C. 1981, if they meet the following criteria:
(a) A common parking court is provided at a ratio of 0.5 additional spaces per unit if
less than two onsite parking spaces, meeting City requirements, are provided on
each single-family lot served by the shared driveway.
(b) The shared driveway is no more than 100 feet long, except in districts zoned RL-
1 (Residential-Low 1), RE (Residential-Estate), and RR1 ( Residential-Rural 1)
and RR 2 (Residential-Rural 2), where the shared driveway may extend up to 300
feet long if each lot accessing the shared driveway exceeds 10,000 square feet.
(c) The number of units served shall be no more than three lots or houses that have
less than 30 feet of usable frontage on the accessing street.
(d) Adequate turnaround for vehicles is provided either on an individual lot or lots.
(e) The driveway is properly engineered and constructed to mitigate any adverse
drainage conditions and is appropriately surfaced for the type of development,
usage, and zoning district.
(f) The Driveway is at least 12 feet wide.
(g) For units not fronting on the accessing street, addressing shall be located near the
entrance to the shared driveway insuring visibility of the numbering from the
street.
(h) A public access easement, a minimum fifteen feet in width, for the benefit and
use of all properties and property owners accessing the shared driveway has been
dedicated and recorded to ensure legal access rights in perpetuity for each
property served.
(i) Driveway spacing conforms with the requirements in Table 2-1, “Access Spacing
Requirements,” of these Standards.
2.05 Right-of-Way Requirements
Dedication or reservation of public right-of-way required as part of any project or development
proposal shall comply with the requirements set forth in Section 9-9-8, “Reservations,
Dedication, and Improvement of Rights-of-Way,” B.R.C. 1981.
2.06 Base Street and Alley Standards
(A) Base Street Standard
Except for residential streets approved pursuant to Chapter 9-12, “Subdivision,” B.R.C. 1981, and
09.12.22 TAB Agenda 6 DCS Transportation
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Effective: February 6, 2020TBD DESIGN AND CONSTRUCTION STANDARDS 2-15
Section 2.09, “Residential Streets,” all new streets shall provide at a minimum the base street
standard components listed in Table 2-3, “Base Street Standard Components.”
(B) Base Alley Standard
Except for residential streets approved pursuant to Chapter 9-12, “Subdivision,” B.R.C. 1981, and
Section 2.09, “Residential Streets,” all new alleys shall provide at a minimum the base alley
standard components listed in Table 2-4, “Base Alley Standard Components.”
Table 2-3: Base Street Standard Components
Street Component Base Standard
Right-of-Way 60' Minimum Width
Paved Street Section 36' Minimum Width, Curb Face to Curb Face
Travel Lanes Two Travel Lanes, Two-Way Traffic
Curb and Gutter Required Both Sides
Parking Parking Allowed Both Sides
Sidewalks 6’ Preferred Width (5' Minimum), Detached, Required Both Sides
Streetscape Planting Strips* 8’ Width Required Both Sides
*NOTE: In commercial streetside retail zones where 12-foot wide attached sidewalks may be provided, streetscape
planting strips may be created using street trees in planting pits with tree grates (15-foot width between back of curb
and back of walk).
Table 2-4: Base Alley Standard Components
Alley Component Base Standard
Right-of-Way 20' Minimum Width
Paved Street Section 18' Minimum Width, Pavement Edge to Pavement Edge
Travel Lanes Two-Way Traffic Allowed
Parking Parking on Alley Not Permitted
2.07 Street Geometric Design
(A) Minimum Requirements
Except for State Highways and the geometric design variations allowed for residential streets
approved pursuant to Chapter 9-12, “Subdivision,” B.R.C. 1981, and Section 2.09, “Residential
Streets,” all city streets shall be designed in conformance with this section. The design standards
outlined in this section are minimum design standards, and all street design shall meet or exceed
these standards. On streets designated collector or arterial in the TMP, the Director may specify
standards to be applied to street design that may exceed the minimum standards in this section
based on functional need to ensure safe and efficient operation of the street.
(B) Right-of-Way
The right-of-way width required for new streets shall comply with the requirements of Section 9-
9-8, “Reservations, Dedication, and Improvement of Rights-of-Way,” B.R.C. 1981, and shall
include without limitation the following elements:
(1) The paved roadway section including without limitation travel lanes, turning and speed
change lanes, transit lanes, bicycle lanes, and parking lanes;
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2-16 DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
(2) Curbs and gutters or drainage swales;
(3) Roadside and median landscaping areas;
(4) Sidewalks and multi-use paths; and
(5) Any necessary utility corridors.
(
C) Lane Width
Street lanes shall meet the minimum width specifications shown in Table 2-5, “Minimum and
4/1Preferred Street Lane Widths,” of these Standards.
Table 2-5: Minimum and Preferred Street Lane Widths
Street Characteristics
Design Criteria With Parking Lane No Parking Lane
With Fixed-Route Bus
Transit Service and No
Parking Lane
Preferred Preferred Preferred
General Purpose
Travel Lanes* 10’ 10’ 121’ (Outside lane)
Auxiliary Lanes* 10’ 9’ 10’
Conventional Bike
Lanes 7’ 6.5’ 7’
Contra-Flow Bike
Lanes (On One-
Way Streets)
7’ 6.5’ N/A
Buffered
Bike
Lanes
Bike
Lane 7’ 6.5’ 6’
Buffer 3’ 3’ 2’
Separated
Bike
Lanes
Bike
Lane
7’
(for parking protected bike
lanes, a painted 3’ buffer is
between curbside of parking
lane and bike lane)
7’ 7’
Buffer 3'’
(with vertical element)
3'’
(with vertical element)
3'’
(with vertical element)
Two-Way
Separated
Bike
Lanes
Bike
Lane
12’
Two-way bike lane (for
parking protected bike lanes,
a painted 3’ buffer is between
curbside of parking lane and
bike lane)
12’
Two-way bike lane (buffer is
between curbside of parking
lane and bike lane)
N/A
Buffer 3'’
(with vertical element)
3'’
(with vertical element) N/A
Parking Lanes
8’
(measured from curb face,
including gutter pan)
N/A 8’ (measured from curb
face, including gutter pan)
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Effective: February 6, 2020TBD DESIGN AND CONSTRUCTION STANDARDS 2-17
*NOTES: Travel, auxiliary lane and bike lane dimensions do not include gutter pan width. Auxiliary lanes include,
without limitation, turning and speed change lanes.
Table 2-5: Minimum and Preferred Street Lane Widths
*NOTES: Travel and auxiliary lane dimensions do not include gutter pan width. Auxiliary lanes include, without
limitation, turning and speed change lanes.
Design
Criteria
Travel
Lanes
*
Auxiliary
Lanes*
Conventional
Bike
LanesOn
-Street
Bike
Lanes
Buffered
Bike
Lanes
Separated
Bike
Lanes
Parking
Lanes
Parking
Lane
With
10'’ 9'’ 6'’ 2'’ buffer
plus, 3’
preferred,
plus 5’ bike
lane, 6’
preferred
3'’ horizontal
vertical buffer
(min. and pref,)
between
curbside of
parking lane and
bike lane, plus
6.5'’ bike lane,
(7’
preferred)buffer
3'’ vertical
buffer3'’
vertical buffer
horizontal
(min. and pref,)
between
curbside of
parking lane
and bike lane,
plus
?'’
minimum,
8’
preferred.
M(measur
ed from
curb face
(inclusive
of gutter
pan)
Parking 5'’ bike lane plus 5'’ bike
lane,
face)
Lane buffer is
between
curbside of
parking lane and
bike lane
Without
No
Parking
Lane
10'’ 9'’ 6.5'’
(Mmeasured
from curb
face
(inclusive of
gutter
pan)6.5'’
(measured
2'’ buffer
plus, 3’
preferred
3'’ vertical
horizontal
buffer (min. and
pref,)., Vertical
barrier type and
dimension may
vary, ,
horizontal (min. and
pref,). Vertical
barrier type and
dimension may
vary, plus min. and
pref.). M (inclusive
of gutter pan)
Parking from curb
face
6.5'’ bike
lane
plus 6.5'’ bike
lane, 7’
preferred.
Lane Measured
from curb
face
(inclusive
of gutter
pan)
(measured
from
Measured from
curb face
(inclusive of
gutter
pan)(measured
from
curb face) curb face)
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2-18 DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
(D) Horizontal Alignment
(1) Conformance to Street Plan: Horizontal alignment shall conform to the pattern of
streets in the Boulder Valley Comprehensive Plan, TMP, and adopted right-of-way plans
and shall provide continuous alignment with existing, planned, or platted streets with
which they will connect.
(2) Extension to Property Line: All streets shall be extended to the property lines across the
property to be developed, unless the street to be constructed has been approved by the
City as a cul-de-sac or other no-outlet street.
(3) Minimum Horizontal Curve: Street curvatures shall meet the minimum specifications
shown in Table 2-6, “Minimum Horizontal Street Curve Specifications,” of these
Standards.
Table 2-6: Minimum Horizontal Street Curve Specifications
Design Criteria Local Street Collector Street Arterial Street
Minimum Design Speed 20 mph 35 mph 40 mph
Minimum Centerline Radius 100 feet 300 feet 500 feet
Minimum Reverse Curve Tangent 50 feet 100 feet 200 feet
Minimum Intersection Approach Tangent 100 feet 200 feet 300 feet
Table 2-6a: Separated Bike Lane Minimum Horizontal Curve Specifications
Design Criteria Flat, level terrain Congested, urban
area
Intersection
approach
Minimum Design Speed 15 mph 12 mph 8 mph
Minimum Centerline Radius* 42 feet 27 feet 12 feet
*Radius assumes a 20-deg lean angle of the bicyclist
(4) Design Horizontal Curve: The design horizontal street curvature shall meet or exceed
the minimum horizontal curvature and be calculated using the following equation:
R = V2 / 15 * (e-f) Side Friction Factors
Where: E = rate of superelevation per foot Design Speed Side Friction
F = side friction factor (mph) Factor (f)
20 0.26
25 0.23
V = vehicle speed in MPH 30 0.22
R = radius of curve in feet 35 0.20
40 0.18
45 0.16
(5) Intersections and Street Spacing
(a) Angles: All streets shall intersect at right angles (90°).
(b) Minimum Street Spacing: Spacing between streets, as measured from centerline
to centerline, shall equal or exceed the minimum distances shown in Table 2-7,
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“Minimum Street Spacing,” of these Standards.
Table 2-7: Minimum Street Spacing
Street Type Minimum Street Spacing
Local 150 feet
Collector 300 feet
Arterial 500 feet
(c) Street Spacing for Signalized Intersections: Signalized intersections, where
feasible, shall be spaced at no more than half-mile intervals. Closer signal
spacing may beis generally desired and may be approved by the Director based
on context-sensitive design. The Transportation Master Plan and Low-Stress
Walk and Bike Network Plan should be consulted when considering placement
of signalized intersections to ensure signalized intersections along arterial and
collector streets provide controlled crossing opportunities where existing and
proposed walking and bicycling network streets cross those arterial and collector
streets..
(d) Receiving Width: The minimum receiving throat width is 20’. This
would include both opposing and receiving vehicle through lane and may
also include a paved shoulder or bicycle lane.
(e)
Corner Radii: Corner design should take into account the effective
turning radius (the curve which vehicles follow when turning, which may
be affected by on-street parking, bicycle lanes, medians, and other
roadway features) prior to selecting a flowline an actual radius. The
smallest feasible flowline actual curb radii should be selected for
corner designs. Figure 1Figure 1 and Figure 2 demonstrate the
relationship between the effective radius and the flowline actual curb
radius.
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2-20 DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
Figure 1. Actual and Effective Radius At A Conventional Intersection
Corner
Figure 2. Actual and Effective Radius At An Intersection Corner With A
Curb Extension
The effective radius should be analyzed for the design vehicle; the default
design vehicle is the SU-30 for all intersections. In some instances, a
different design vehicle may be warranted (i.e., a bus on transit routes, a
semi-truck on industrial streets).
An important companion to understanding the effective radius and
selecting the flowline actual curb radius is the allowable encroachment.
While the default design vehicle is the SU-30, encroachment is allowable
to different degrees based on the street type(s). The following should be
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considered when selecting the radii:
At turns onto Local streets (from Arterials, Collectors, or Locals),
the design vehicle can use the entire width of the departing and
receiving lanes, including oncoming travel lanes, to negotiate the
turn.
At intersections where the minor leg is stop controlled and the
major leg is uncontrolled, the design vehicle can use the entire
width of the departing (if minor leg) or receiving (if minor leg)
lanes, including oncoming travel lanes, to negotiate the turn.
At signalized intersections where the design vehicle can utilize
multiple lanes on the receiving street to complete their turn; in this
scenario it may be necessary to implement a “No Right on Red”
restriction.
The “throat width”, or the curb-to-curb width at the block end,
should be considered when selecting the curb radius, as it may
decrease the space available for encroachment.
1
In addition to encroachment for the design vehicle, the following should
be considered for other types of vehicles:
Transit agency operators may have policies that prohibit drivers
from encroaching into adjacent lanes.
It is assumed that emergency vehicles are able to use the entire
street right-of-way to negotiate turns, including all adjacent and
oncoming travel lanes.
Large trucks are assumed to be able to use adjacent lanes on the
departing and receiving streets at all intersections; large trucks may
use the entire street right-of-way on Local streets.
It may be necessary to recess a stop bar on the intersecting street if
large vehicles make regular turns at the intersection; this practice
should be limited for use as a strategy only at locations where
vehicle encroachment over a stop line would occur regularly and
presents operational or safety issues if not corrected.
A dashed centerline may be used if large vehicles make infrequent
turns at an intersection but require space from an oncoming lane to
negotiate the turn.
Restricting turns may be necessary, especially with considering the
use of traffic calming elements on Local streets; for instance, the
planning and placement of traffic circles may require restricting
turns for larger vehicles.
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A mountable truck apron may be considered in instances where
large trucks turn infrequently, but there is limited space for
encroachment. The truck apron provides a smaller effective radius
for the design vehicle but makes a larger effective radius available
to accommodate larger vehicle off-tracking. Figure 3 below shows
an example of this potential scenario.
Figure 3. Example of A Mountable Truck Apron At An Intersection
Corner
The minimum property line corner and flowline radii at intersections
shall meet or exceed the minimum radii specifications shown in Table
2-8, “Minimum Intersection Radii,” of these Standards.
Table 2-8: Minimum Intersection Radii
Stre
et
Typ
e
Min
imu
m
Flo
wli
ne
Rad
ius
Min
imu
m
Pro
pert
y
Rad
ius
Loc
al
5
feet
15
feet
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Coll
ecto
r
15
feet
15
feet
Art
eria
l
20
feet
10
feet
Table 2-8a: Relationship between Effective and Actual Radius for the Default Design Vehicle (SU-
30)
Street B
Parking No No Yes Yes
Bike Lane No Yes No Yes Street A Parking Bike Lane
No No RA = 30’
(RE = 30’)
RA = 25’
(RE = 30’)
RA = 25’
(RE = 30’)
RA < 10’
(RE = 30’)
No Yes RA = 25’
(RE = 30’)
RA = 15’
(RE = 30’)
RA < 10’
(RE = 30’)
RA < 5’
(RE = 30’)
Yes No RA = 25’
(RE = 30’)
RA < 10’
(RE = 30’)
RA < 5’
(RE = 30’)
RA < 5’’
(RE = 35’)
Yes Yes RA < 10’
(RE = 30’)
RA < 5’
(RE = 30’)
RA < 5’
(RE = 35’)
RA < 5’
(RE = 45’)
(c)(f) *when the difference between the effective and actual corner radii
becomes larger, or when the effective radius cannot be reduced to what is
necessary for the control vehicle, the design should consider using a curb
extension
(6) Road Width Transition Tapers: Where two street sections or different widths are to be
connected, a transition taper is required between the outside traveled edge of the two
sections. The length of the transition taper shall be calculated using the following
equation:
L = WS
Where: S = Speed in MPH
L = Length in feet
W = Width of offset in feet
This transition is not to be used in the design of left turn storage lanes or speed change
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2-24 DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
lanes.
Design of tapers for on-street bike lanes should use a minimum length as calculated using
the formula below:
𝐿 =
𝑊𝑆ଶ
60
Where: L = Longitudinal lane shift (ft), minimum 20 ft
W = Lateral width of offset (ft)
S = Target bicyclists operating speed (mph)
If the bikeway is delineated by paint-only, and if the off-tracking of a bicycle pulling a
trailer would not put the trailer into a motor vehicle lane, a maximum taper ratio of 2:1
(longitudinal:lateral) may be considered.
(7) Left Turn Lanes
(a) Storage Length: Left turn lane storage length for unsignalized intersections
shall be determined based on traffic volumes using the Leisch nomographs
provided in the ITE “Guidelines for Major Urban Street Design.” The left turn
lane storage length shall not be less than 50 feet. The left turn storage length for
an unsignalized intersection shall not be less than 25 feet. Left turn lane storage
length for signalized intersections is determined utilizing the Highway Capacity
Manual. For signalized and unsignalized intersections, Llengthening single left
turn lanes to the maximum extent feasible should be exhausted before including
dual turn lanes. Where dual left turn lanes are provided, the lane storage length
shall be based on at least 60 percent of the single lane storage length. The left
turn lane storage length of any single or dual left turn lanes shall not be less than
80 feet. Double or Ttdrivriple left turn lanes are only allowed with Director
approval.
(b) Lane Change Taper: Left turn lane change tapers shall be calculated using the
equation for bay tapers in Subsection (8).
(8) Speed Change Lanes: Speed change lanes required for transitional access to turning
lanes shall be designed according to the design standards provided in the ITE “Guidelines
for Major Urban Street Design,” as follows:
(a) Bay Tapers: Bay tapers are required for the lane transition from the travel lane
into a turn lane. The bay taper length shall be calculated using the following
equation:
L = WS / 3
Where: S = Speed in MPH
L = Length in feet
W = Width of offset in feet
(b) Approach Tapers: Approach tapers are required to transition the position of
travel lanes to accommodate turn lanes. The approach taper length shall be
calculated using the following equation:
L = WS2 / 60
Where: S = Speed in MPH
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L = Length in feet
W = Width of offset in feet
(9) Cul-de-sacs: Where allowed, cul-de-sacs shall have a minimum pavement diameter of
90 feet, curb face to curb face, and a minimum right-of-way diameter of 115 feet, except
for residential streets approved pursuant to Chapter 9-12, “Subdivision,” B.R.C. 1981,
and Section 2.09, “Residential Streets.” Cul-de-sacs are prohibited on arterial and
collector streets, and are strongly discouraged on local and residential streets. The
Director may permit cul-de-sacs where there is no other possible street or driveway
access to a property from a public right-of-way, or if a cul-de-sac would avoid direct
property access to a collector or arterial.
(E) Vertical Alignment
(1) Minimum Street Grade: All street grades shall equal or exceed the minimum street
grade of 0.5 percent.
(2) Maximum Street Grade: Street grades shall not exceed the maximum street grades
shown in Table 2-9, “Maximum Street Grades,” of these Standards.
Table 2-9: Maximum Street Grades
Street Type Maximum Street Grade
Local 8%
Collector 6%
Arterial 5%
Intersection Approach (Minimum 50') 4%
Signalized Intersection Approach (Min. 50') 2%
(3) Design Controls for Vertical Curves: Design control for sag and crest vertical curves,
(based on a design speed of 30 mph) shall meet the specifications shown in Table 2-10,
“Vertical Curve Design Control,” of these Standards. For design speeds in excess of 30
mph, design control shall be in accordance with the current edition of “A Policy on
Geometric Design of Highways and Streets,”, prepared by the American Association of
State Highway and Transportation Officials.
Table 2-10: Vertical Curve Design Control
Algebraic Difference in
Grades
Sag Curve
Minimum Vertical Curve Length
Crest Curve
Minimum Vertical Curve Length
0.5 - 1.0 % 50 feet 100 feet
1.0 - 3.0 % 100 feet 100 feet
3.0 - 5.0 % 200 feet 150 feet
5.0 - 7.0 % 300 feet 200 feet
7.0 - 8.0 % 300 feet 300 feet
Min. Vert. Sight Distance N/A 250 feet
(4) Vertical Sight Distance: Vertical curve sight distance shall equal or exceed 250 feet.
Greater vertical sight distance may be required by the Director to ensure safe travel and
street crossings for all transportation modes.
(F) Sight Distance
All streets and alleys shall provide adequate sight distance as set forth under Section9-9-7, “Sight
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2-26 DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
Triangles,” B.R.C. 1981.
(1) Design Sight Distance for Separated Bike Lanes: On streets with separated bike lanes
that provide a parking lane between the outside motor vehicle travel lane and the
separated bike lane, parking should be restricted within 20 feet of driveways to provide
adequate sight distance where motor vehicles turn across the separated bike lane.
Additionally, where side streets intersect the separated bike lane, intersections should be
designed for a two-stage crossing scenario where the motorist will first assess the
separated bike lane conflicts, then move forward and assess motor vehicle conflicts. The
equation in Table 2-XX can be used to calculate the departure sight triangle between a
passenger vehicle and the bikeway using a time gap (t g) of 5.5 seconds for the motorist to
clear the bikeway. This time gap uses an assumption that the vertex (decision point) of
the departure sight triangle is 10 ft from the edge of bikeway and the bikeway width is no
wider than 14 ft. The appropriate AASHTO Green Book Case B sight distance can then
be used to calculate departure sight triangle between the motorist and the intersecting
motorist travel lanes. Designers should reference Table 2.6a: Separated Bike Lane
Minimum Horizontal Curve Specifications earlier in this chapter to establish the Vbike of a
given project.
Table 2-XX: Separated Bike Lane Intersection Sight Distance
𝐼𝑆𝐷 =1.47 𝑉 𝑡
Where:
ISDbike = intersection sight distance (length of the leg of sight
triangle along the bikeway) (ft)
Vbike = design speed of bikeway (mph)
tg = time gap for passenger vehicle to cross bikeway (s)
(G) Medians
Raised medians are required on new arterial streets. Raised medians, where feasible,
shall extend past the pedestrian crosswalk to allow for a pedestrian refuge zone.
(1) Median Widths: Medians shall be at least 4 feet wide, curb face to curb face. If left turn
lanes are installed in the median, the median width adjacent to the left turn storage lanes
shall be 4 feet and the median width at the start of the left turn lane bay taper shall be at
least 14 feet wide, curb face to curb face. Median design widths shall conform to Table
2-11, “Median Width Design Standards,” of these Standards.
Table 2-11: Median Width Design Standards
Function Minimum Width Recommended Width
Separation of Opposing Traffic 4 feet* 10 feet*
Pedestrian Refuge or Traffic Control Device Location 6 feet* 14 feet
Medians Separating Left Turn Lanes 14 feet 20 feet
* NOTE: Cannot accommodate left-turn lanes
(2) Landscaping in Medians: Landscaping in medians shall comply with the requirements
of Chapter 3, “Streetscaping,” of these Standards.
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(H) Vertical Clearance of Structures
At least 17.5 feet of vertical clearance shall be provided for all overhead structures. Vertical
clearance is measured from the crown of the street to the lowest portion of the structure on all
streets and alleys.
2.08 Sidewalks
(A) Required
Sidewalks are required on both sides of all new streets, except for residential streets that were
approved without required sidewalks pursuant to Chapter 9-12, “Subdivision,” B.R.C. 1981, and
Section 2.09, “Residential Streets.”
(B) Conformance with the Transportation Master Plan
Off-street sidewalks may be required as part of any project or development proposal in
conformance with the TMP.
(C) Compliance with Americans with Disabilities Act (ADA)
All public sidewalks shall comply with the requirements of the ADA’s “Standards for Accessible
Design,” which includes without limitation sidewalk widths, grades, locations, markings, surface
treatments, and access ramps.
(D) Minimum Widths
Sidewalk widths shall conform to the dimensions shown in Table 2-12, “Minimum Sidewalk
Widths,” of these Standards.
Table 2-12: Minimum Sidewalk Widths
Minimum Sidewalk Width
Adjacent Land Use
Street Type Commercial/Retail Commercial/Industrial Residential
Local 12 5 4
Collector 12 5 5
Arterial 12 8 8
Note: All off-street multi-use/bike paths designated in the Transportation Master Plan shall be 12 feet wide.
(E) Vertical Grades
The vertical grade of a sidewalk shall not exceed 8.33 percent, a ratio of 12 feet horizontal to 1
foot vertical (12:1).
At sidewalk locations adjacent to transit stops or transfer points, the Director may require wider
sidewalk sections to provide for adequate passenger storage areas.
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2-28 DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
(F) Vertical Clearance
A minimum 8 foot vertical clearance shall be provided between all sidewalk and multi-use path
surfaces and any overhead encroachments.
2.09 Residential Streets
(A) Purpose
(1) The residential street standards were developed to allow a variety of choices in the
creation of new transportation corridors within the urban environment under conditions
that will not compromise the safety and function of the city street system. Traditionally
streets have provided the following:
(a) Corridors for pedestrian, bicycle, transit, and motor vehicle movement;
(b) Parking for vehicles;
(c) Fire, police, and emergency access;
(d) Locations for public utilities networks including water supply, sewage,
electricity, telecommunications and gas services, and refuge disposal; and
(e) Postal and other delivery services.
(2) These standards recognize that streets, if appropriately designed, may provide additional
community amenities including landscape buffers, attractive public gathering spaces,
opportunities for neighborhood interaction, public art, view corridors, and potential
avenues for new technologies.
(B) Scope
(1) Location of Streets
(a) These standards are intended to be used for new streets in undeveloped areas of
the city.
(b) Where infill development in the existing developed portions of the city requires
the creation of new streets, these alternative standards may be used if the Director
finds, after completing the review process described in Section (C) below, that
the new streets will not impair the functions of the surrounding transportation
system nor negatively impact the character of the surrounding existing
development.
(c) Further, the Director may determine that these standards are appropriate for
redesigning and reconfiguring existing streets. Because the public cost of
retrofitting, reconfiguring, or redesigning existing streets is often expensive,
decisions about reconstruction of individual streets in accordance with these
standards shall be made pursuant to the city’s Capital Improvements Program
process.
(2) Methods of Review
(a) Permitted: The following street types may be developed without review:
(i) Residential collector street
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(ii) Residential street
(iii) Residential alley
(b) By Director Review: Residential streets listed in paragraph (B)(2)(a) and the
street types listed below may be developed upon approval by the Director under
the criteria outlined in Section (C) below.
(i) Rural residential street
(ii) Access street
(iii) Access lane
(c) By Site Review: Those underlined criteria and specifications in the following
residential street standards may be appropriate for modification under certain
limited circumstances. Developments requesting such modifications shall meet
all of the requirements of Section 9-2-14, “Site Review,” B.R.C. 1981, in
addition to the criteria outlined in Subsection (C), “Director Review,” below.
(3) Cumulative Standards: These street standards are intended to be used in combination
with Section 2.07, “Street Geometric Design,” of these Standards. Where the standards
in this section are silent, the criteria or specifications contained in Section 2.07 shall
control.
(C) Director Review
(1) Application: As part of a subdivision application, the applicant for residential street
construction approval shall include plans that depict the building envelopes of all
proposed structures, and the location of proposed trees, street furniture, fire hydrants,
meter pits, utility cabinets, or pedestrians in the right-of-way.
(2) Criteria: The Director will consider the following factors in determining whether an
alternative street design is appropriate in a particular location:
(a) Urban Design: The street should contribute to the creation of an attractive
community and to a clearly defined sense of place. Streets shall be designed with
due attention to building spacing and setbacks, green spaces, attractive materials,
plantings, and landscaping. Pavement and right-of-way widths that are less than
the Residential Street standard should provide a benefit to the community that
includes improved safety, improved site design, the creation of street canopies
through landscaping, and secondary lot access through the use of alleys. Rural
Residential streets shall be consistent with the existing character of the area, or
with an approved subcommunity or area plan.
(b) Street Function: The street should be designed according to its function. This
may require a diversity of street types, each serving a role in a hierarchical
system. The street pattern and any reduced pavement or right-of-way widths
should provide acceptable levels of accessibility, safety and convenience for all
street users, including emergency service providers. The pattern shall discourage
residential streets from operating as pass through traffic routes for externally
generated traffic, while minimizing the length of time local drivers need to spend
in a low-speed environment.
(c) Connectivity: The neighborhood street pattern should be simple, and logical,
with the following characteristics:
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(i) “No outlet” streets will be highly discouraged and allowed only when
street connectivity is unachievable:
(ii) The street pattern provides for safe and convenient movements for
pedestrians, bicycles, and motor vehicles, including transit.
(d) Design Speed: The design of the streets will control vehicular speeds under
normal driving conditions to that specified in the residential street standards,
while maintaining reasonable access for emergency vehicles.
(e) Minimize Maintenance Costs: The street will not create additional city
obligations for maintenance and repair that exceed a standard street section.
(f) Adequate Parking: The site design provides for adequate on-street and off-street
parking to serve the area.
(g) Infill Streets: In the case of infill development, the residential street design will
not impair the functioning of, and will have a compatible transition to, the
surrounding street system and will not negatively impact the character of the
surrounding existing development. No additional density may result from
approval of the reduced rights-of-way provided for in the case of Access Streets,
Access Lanes, or Residential Alleys.
(D) Residential Street Sections
Five residential street sections and a residential alley may be applied to the design of residential
neighborhoods as part of subdivisions approved pursuant to Chapter 9-12, “Subdivision,” B.R.C.
1981. Residential streets shall be designed in compliance with the standards outlined in Table
2-13, “Residential Street Design Standards,” “Technical Drawings 2.63 - 2.68,” Chapter 11, of
these Standards, and the requirements of this Section.
(1) Residential Collector Street: The residential collector street collects and distributes
neighborhood traffic from residential streets to community collector and arterial
transportation systems, and provides access to individual properties. The residential
collector street is designed for residential streets where anticipated traffic volumes range
from 1,000 to 2,500 vehicle trips per day. In addition to the requirements outlined in
Table 2-13, “Residential Street Design Standards,” and “Technical Drawing 2.63,”
Chapter 11, the residential collector street shall be designed to meet the following
minimum standards:
(a) Parking: On-street parking is allowed on both sides.
(b) Bicycle Facilities: Additional street and right-of-way width shall be provided
where on street bicycle lanes are required by a City-adopted subcommunity or
area plan, the TMP, or the BVCP.
(c) Provision of Alleys: Where alleys are provided or required to be provided under
a City-adopted subcommunity or area plan, onsite parking spaces shall be
accessed from the alley and not the street.
(d) Emergency Response: Residential collectors exceeding 500 feet in length from
any intersection shall provide a secondary emergency access at 500-foot
intervals.
(2) Residential Street: The residential street is designed to provide access to individual
properties as well as access to the higher classification street network. The residential
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Effective: February 6, 2020TBD DESIGN AND CONSTRUCTION STANDARDS 2-31
street provides for neighborhood circulation and may carry neighborhood traffic and
through movements. The residential street shall be designed to meet the minimum
standards shown in Table 2-13, “Residential Street Design Standards,” and “Technical
Drawing 2.64,” Chapter 11, of these Standards.
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2-32 DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
Table 2-13: Residential Street Design Standards
Design
Standards
Residential
Collector
Residential
Street
Rural-Type
Residential
Street
Access
Street
Access
Lane
Residential
Alley
Design Speed 25 mph 25 mph 20 mph 15 mph 10 mph 10 mph
Design Traffic Volumes
(Vehicle Trips Per Day)
1,000 -2,500 500 - 1,000 500 - 1,000 400 250 N/A
Minimum Right-of-Way 60' 60' 60' 40' 30' 16'
Minimum Pavement
Section
32' 30' 22' plus 2'
gravel
shoulders
26' 20' 12'
Sidewalk 5' 4' 4' where
required
4' N/A N/A
Streetscape Planting
Strip
8' 8' N/A N/A N/A N/A
Minimum Centerline
Radius
300' 150' 150' 100' 100' 100'
Minimum Curb Radius 20' 20' 20' 10' 10' 10'
Maximum Length
Between Connecting
Streets
500' 500' 500' 350' 350' N/A
Maximum Street
Length - No Outlet
500' 500' 500' 150' 150' 500'
Maximum Street
Length - Loop or Circle
Street
500' 500' 500' 500' 500' 500'
Minimum Turn-Around
Area
35' Radius 35' Radius 30' Radius
or “Y” or
“T” Turn
30' Radius
or “Y” or
“T” Turn
25'
Radius or
“Y” or
“T” Turn
25' Radius
or “Y” or
“T” Turn
Emergency Response
Set Up Area Intervals
N/A N/A N/A 150' 150' N/A
Sidewalk Placement Detached
Required
Detached
Required
Adjacent to
Property
Line Where
Required
Attached N/A N/A
Curb and Gutter Required Required N/A Required N/A N/A
On-Street Parking Allowed Allowed Allowed Allowed Allowed Not
Allowed
Minimum Lot Frontages N/A N/A 60’ no alley
40’ w/ alley
60' no alley
40' w/alley
60' N/A
Maximum Number of
Units to be Accessed
N/A N/A N/A 25 single
family
15 single
family
N/A
NOTE: Residential street standards that are underlined may be varied through Section 9-2-14, “Site Review,”
B.R.C. 1981.
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(a) Parking: Parking is allowed both sides or, on residential streets where parking is
restricted or prohibited, off-street parking courts providing parking spaces at a
ratio of 0.5 spaces per dwelling unit shall be provided.
(b) Bicycle Facilities: Additional street and right-of-way width shall be provided
where on-street bicycle lanes are required by a City-adopted subcommunity or
area plan, the TMP, or the BVCP.
(c) Provision of Alleys: Where alleys are provided or required to be provided under
a City-adopted subcommunity or area plan, onsite parking spaces shall be
accessed from the alley and not the street.
(d) Emergency Response: Residential streets exceeding 500 feet from any
intersection shall provide a secondary emergency access at 500-foot intervals.
(3) Rural Residential Street: The rural residential street is designed to provide access to
individual properties as well as access to the higher classification street network. The
rural residential street provides for neighborhood traffic and through movements, and is
designed to carry traffic volumes in the range of 500 to 1,000 vehicles per day. The rural
residential street shall be provided where prescribed by a City-adopted subcommunity or
area plan to maintain the rural character of an area or neighborhood. The rural residential
street is a curbless paved street section, with gravel shoulders for parking and open
roadside ditches for drainage. In addition to the requirements outlined in Table 2-13,
“Residential Street Design Standards,” and “Technical Drawing 2.65,” Chapter 11, the
rural residential street shall be designed to meet the following standards:
(a) Parking: Allowed on both sides of the street.
(b) Turnaround Standard (No Outlet Streets): If a “Y” or “T” turnaround is proposed
in place of a standard cul-de-sac bulb turnaround, the “Y” or “T” turnaround
shall be designed 60 feet long and 20 feet wide. The turnaround area (including
sidewalks if required) shall be contained within the dedicated right-of-way.
(c) Provision for Future Sidewalks: If sidewalks are not required at the time of initial
street construction, adequate space in the right-of-way shall be reserved for a
future sidewalk and commitments from adjacent property owners to participate in
assessment districts shall be obtained, so that sidewalks can be added and funded
in the future when they are appropriate.
(d) Sidewalk Placement (Where Required): Sidewalks shall be required where
vehicular traffic volumes are anticipated to exceed 1,000 trips per day, on routes
to school, and as prescribed by a City-adopted subcommunity or area plan.
Sidewalks shall be placed outside of the paved roadway and drainage ditch, and
inside the right-of-way line.
(e) Roadside Drainage Ditches: Sideslopes along roadside drainage ditches shall be
4:1, and driveway culverts, at least 12 inches in diameter with flared end sections
or headwalls, shall be installed by owners at driveways.
(f) Land Use Requirements: Lot frontages shall be at least 60 feet wide, unless alley
access is provided. Lot frontages with alley access shall be at least 40 feet wide.
Two onsite parking spaces, meeting all City requirements, shall be provided on
each single-family lot.
(g) Provision of Alleys: Where alleys are provided or required to be provided under
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a City-adopted subcommunity or area plan, onsite parking spaces shall be
accessed from the alley and not the street.
(h) Emergency Response: Rural residential streets exceeding 500 feet from any
intersection shall provide a secondary emergency access at 500-foot intervals.
(4) Access Street: The access street provides public access to no more than 25 single-family
dwelling units, where anticipated vehicular volumes would not exceed 400 trips per day.
The access street is narrow, to ensure slower speeds for vehicular travel, and provides
sidewalks along both sides of the street. In addition to the requirements outlined in Table
2-13, “Residential Street Design Standards,” and “Technical Drawing 2.66,” Chapter 11,
the access street shall comply with the following minimum standards:
(a) Parking: Parking is allowed on both sides of the street or, if parking is not
provided on-street, a parking court at a ratio of 0.5 spaces per dwelling unit is
required.
(b) “L” Intersections: “L” intersections may be permitted as part of subdivision, and
are subject to approval by the Director. Where permitted, “L” intersections shall
have at least a 150-foot-long tangent street section from the intersection to the
closest curvature and a minimum corner radius of 50 feet.
(c) Circle or Loop Street: If a circle or loop street is proposed as part of subdivision,
the street shall connect to a higher classification street, or connect to two separate
perpendicular or offset higher classification streets.
(d) Turnaround Standard (No outlet streets): If a “Y” or “T” turnaround is proposed
in place of a standard cul-de-sac bulb turnaround, the “Y” or “T” turnaround
shall be designed with a 60 foot length, 20 foot width. The turnaround area
(including sidewalks if required) shall be contained within dedicated
right-of-way.
(e) Land Use Requirements: A residential access street shall connect to a higher
classification street. Lot frontages shall be at least 60 feet wide, unless alley
access is provided. Lot frontages with alley access shall be at least 40 feet wide.
Two onsite parking spaces, meeting all City requirements, shall be provided on
each single-family lot.
(f) Provision of Alleys: Where alleys are provided or required to be provided under
a City-adopted subcommunity or area plan, onsite parking spaces shall be
accessed from the alley and not the street.
(g) Emergency Response: Access streets exceeding 175 feet from any intersection
shall provide a fire apparatus setup area at 150 foot intervals. The setup area shall
provide at least 30 foot long, 25 foot wide clear zone, and is subject to approval
by the Fire Department.
(5) Access Lane: The access lane provides public access to no more than 15 single family
dwelling units, where anticipated vehicular traffic volumes would not exceed 250 trips
per day. The access lane is a narrow “shared street” for all modes of travel (vehicular,
bicycle, and pedestrian), without curb and gutter or sidewalks, and must connect with a
higher classification street. In addition to the requirements outlined in Table 2-13,
“Residential Street Design Standards,” and “Technical Drawing 2.67,” Chapter 11, the
access lane shall comply with the following minimum standards:
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(a) Parking: Parking is allowed.
(b) “L” Intersections: “L” intersections shall have a minimum 150-foot long tangent
street section from the intersection to the closest curvature and a minimum corner
radius of 50 feet.
(c) Circle or Loop Street: A circle or loop street shall connect to a higher
classification street, or connect to two separate perpendicular or offset higher
classification streets.
(d) Turnaround Standard (No outlet streets): A “Y” or “T” turnaround shall be
designed with a 60 foot length, 20 foot width. The turnaround area (including
sidewalks if required) shall be contained within dedicated right-of-way.
(e) Land Use Requirements: An access lane shall connect to a higher classification
street. Lot frontages shall be at least 60 feet wide. Two onsite parking spaces,
meeting all City requirements, shall be provided on each single-family lot. If the
minimum lot frontage requirement is not met, additional parking spaces shall be
provided at a ratio of 0.5 spaces per dwelling unit as a part of the subdivision.
These required spaces shall be located on private property.
(f) Right-of-Way Landscaping: Landscaping other than ground cover or low
shrubbery shall be placed outside of the right-of-way.
(g) Emergency Response: Access streets exceeding 175 feet from any intersection
shall provide a fire apparatus setup area at 150 foot intervals. The setup area
shall provide a minimum 30-foot long, 25 foot wide clear zone, and is subject to
approval by the Fire Department.
(6) Residential Alley: The residential alley is to provide secondary vehicular access to the
rear of lots in detached single-family dwelling subdivisions with narrow street frontages,
in order to limit curb cuts from the street and increase on-street parking. Alleys are most
beneficial when lot widths are narrower than 50 feet. In addition to the requirements
outlined in Table 2-13, “Residential Street Design Standards,” and “Technical Drawing
2.68,” Chapter 11, the residential alley shall be designed to meet the following minimum
land use requirements: Backup distance for parking and garage access from the alley
shall be 24 feet, including the 16-foot alley right-of-way width, and the remaining backup
distance shall be provided on the lot being served.
2.10 Emergency Access Lanes
(A) Emergency Access Required
All industrial, commercial, and residential developments shall provide adequate emergency
vehicle access. Adequate emergency access is a minimum 20 foot wide unobstructed fire
apparatus access road with an unobstructed vertical clearance of 15 feet, and meets all applicable
standards as set forth in Chapter 10-8, “Fire Prevention Code,” B.R.C. 1981.
(B) When Emergency Access Lane is Required
When adequate emergency access is not available from a public street, an applicant for
construction approval shall construct an emergency access lane. Emergency access lanes must
accommodate all emergency vehicles, including fire equipment.
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(C) Secondary Emergency Access
Secondary emergency access lanes shall be provided to structures whenever the distance to the
nearest public street equals or exceeds 500 feet. Secondary access lanes shall conform to all
design requirements specified for emergency access lanes.
(D) Local Emergency Access Lane Standards
In addition to the emergency access standards set forth in Chapter 10-8, “Fire Prevention Code,”
B.R.C. 1981., an emergency access lane shall equal or exceed the following standards:
(1) Direct Route: Emergency access lanes shall provide the shortest practical direct access
to points of concern, and be entirely contained within a minimum, continuous 20 foot
wide emergency access easement or public right-of-way.
(2) Distance From Structure: Emergency access lanes shall be provided whenever a
structure is located more than 150 feet from fire apparatus access.
(3) Surface: An emergency access lane shall consist of either of the following:
(a) Two concrete strips at least 4 feet wide, with a 4-foot separation between them.
Vegetation other than grass shall not be permitted in the separation area.
(b) A minimum continuous paved surface width of 12 feet.
(4) Radius: An emergency access lane shall provide a minimum turning radius of 25 feet, or
the radius needed to accommodate an SU-30 vehicle.
(5) Turnarounds: If the length of the emergency access lane exceeds 150 feet (without an
outlet accessible to emergency vehicles), then a turnaround with a minimum radius of 45
feet shall be provided.
(6) Grade: The grade for an emergency access lane shall not exceed five percent.
Exceptions may be allowed with specific approval from the City of Boulder Fire Chief
where this standard cannot be met due to topographical conditions.
(7) Vertical Clearance: Vertical clearance from the surface of the emergency access lane
shall be at least 15 feet.
(E) Unobstructed Access
Emergency access lanes shall be kept free and clear of all obstructions. If the Director or Fire
Chief determines that barriers are needed to prevent automobile traffic from using an emergency
access lane, then the applicant for construction approval shall install traffic bollards. Traffic
bollard designs shall provide for immediate access of emergency vehicles, without requiring these
vehicles to stop and maneuver around, or unlock, any structures. The Director and Fire Chief
shall have final approval of all bollard designs.
(F) Access Identification
Signs and pavement markings will be required if necessary by the Director and Fire Chief to
delineate and identify emergency access lanes. All signage for emergency access lanes shall
conform with the specifications in the MUTCD.
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2.11 Bicycle Facilities and Multi-Use Path Design
(A) Conformance with Low-Stress Walk and Bike Network Plan
The arrangement, type, and location of all bike lane and multi-use path facilities and routes shall
conform with the "Low-Stress Walk and Bike Network Plan" section in the TMP. The Director
shall specify the standards for design and construction of new bike lane and multi-use path
facilities consistent with these Standards and considering public health, safety, and welfare and
generally accepted engineering principles. The Director may refer to the Transportation
References in these Standards. The City endorses marked and signed contraflow bike lanes to
meet bicycle connectivity goals identified in the Low-Stress Walk and Bike Network Plan to meet
connectivity goals where right of way is constrained.
(B) On-Street Bike Lanes - Streets Without On-Street Parking
An on-street bike lane is separated from the motor vehicle travel lane by a single white line. On-
street bike lanes on new streets without on-street parking shall be at least 5 feet wide, exclusive of
the curb pan, or 6.5 feet from the face of any curb. On existing streets where on-street bike lanes
are being added and available right-of-way or improvements space is restricted, the Director of
Public Works may approve a reduced width of the bike lane; the reduced width shall be at least 5
feet wide, inclusive of the curb pan.
(C) On-Street Bike Lanes - Streets With On-Street Parking
An on-street bike lane on a street with on-street parking is separated from the motor vehicle travel
lane or parking lane by a single white line. On-street bike lanes on new streets with on-street
parking shall be at least 6 feet wide, exclusive of the parking lane. On existing streets where on-
street bike lanes are being added and available right-of-way or improvements space is restricted,
the Director of Public Works may approve a reduced width of the bike lane; the reduced width
shall be at least 5 feet wide, exclusive of the parking lane.
(D) Buffered Bike Lanes
A buffered bike lane is separated from the motor vehicle travel lane by a painted buffer space
creating a greater separation between the bike lane and adjacent travel lane. The buffer shall be
marked with 2 solid white lines, and the markings shall otherwise conform with MUTCD
standards. The buffered space shall be at least 2 feet wide. On streets without on-street parking
the bike lane shall be at least 5 feet wide, or 6.5 feet from the face of the curb. Bike lanes on new
streets with on-street parking shall be at least 5 feet wide, exclusive of the parking lane. On
existing streets where buffered bike lanes are to be added and right-of-way or improvement space
is limited, the Director may modify this standard considering safety concerns or approve an on-
street bike lane..
(E) Separated Bike Lanes (One-Way and Two-Way)
A separated bike lane is physically separated from the motor vehicle travel lane through vertical
or horizontal elements and is distinct from the sidewalk. Separated bike lanes have different
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forms but all share common elements. Where on-street parking is allowed, the separated bike lane
shall be located to the curb side of the parking (in contrast to on-street and buffered bike
lanes). Separated bike lanes may be one-way or two-way and may be at street level, at sidewalk
level, or at an intermediate level. If located at sidewalk level, a curb or median shall separate the
separated bike lane from the motor vehicle travel lane, and different pavement color or type shall
separate the separated bike lane from the sidewalk. If located at sidewalk level, the separation
may include a landscaped area. If located at street level, the separated bike lane shall be separated
from the motor vehicle travel lane by raised medians, on-street parking, or flexible delineators.
Flexible delineators shall conform with MUTCD standards. Raised medians shall conform to
"Technical Drawing 2.42C," Chapter 11 of these Standards. The Director may require additional
markings, signage, and other improvements to ensure safe and efficient operation of the City's
transportation system.
On streets without on-street parking, a vertical separation shall create a buffer between the bike
lane and the travel lane that is at least 3 feet wide, and the bike lane shall be at least 5 feet wide,
or 6.5 feet from the face of the curb. On streets with on-street parking, the separation shall be a 3-
foot-wide horizontal buffer between the bike lane and the parking lane, and the bike lane shall be
at least 5 feet wide.
On existing streets where separated bike lanes are to be added and right-of-way or improvement
space is limited, the Director may modify this standard considering safety concerns and the
efficient operation of the City's transportation system.
Examples of one-way separated bike lanes at driveways are shown in the figures below:
Figure 4 - Typical Layout for One-way Street Level Separated Bike Lanes at Driveways
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Effective: February 6, 2020TBD DESIGN AND CONSTRUCTION STANDARDS 2-39
Figure 5 - Typical Layout for Sidewalk Level One-way Separated Bike Lanes at Driveways
Notes:
1. Design plans should be consulted for variations
2. Typical approach clear space (ACS) for driveways and alleys should be 20' as shown. in
constrained locations the approach clear space may be measured from edge of driveway
3. In constrained locations the far-side buffer tangent may be reduced to 5'
4. See city of boulder design and construction standards, section 2.07, table 2.5 for standard
lane widths
5. Bike lane tapers preferred at 7:1 shift, minimum 3:1 shift in constrained locations where
speed is ≤ 13 mph
6. For bike lanes at sidewalk elevation without buffer treatment, 1' minimum directional
indicator strip required within the sidewalk; typically located 1' from the edge of the bike
lane.
7. Accessible ramp slope (RMP) = 7.8% (8.3% max)
8. Accessible cross slope (CXS) = 0.5-1.5% (2% max)
9. Accessible running slope (RNG) = 5% max
10. Driveway slope (DWY) = 12% max
Examples of one-way separated bike lanes at intersections with protected corners are shown in
the figures below:
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2-40 DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
Figure 6 - Typical Layout of Street Level Separated Bike Lanes at Intersection in Retrofit
Conditions
Figure 7 - Typical Layout of Street Level Separated Bike Lanes at Intersections in Reconstructed
New or Retrofitted Conditions
Notes:
1. Design plans should be consulted for variations
2. Size and shape of corner treatments are dependent on intersection characteristics
3. See city of boulder design and construction standards, section 2.07, table 2.5 for standard
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lane widths
4. Bike lane tapers preferred at 7:1 shift, minimum 3:1 shift in constrained locations where
speed is ≤ 13 mph
Examples of one-way separated bike lanes at intersections with non-protected corners are shown
in the figures below:
Figure 8 - Typical Layout of One-way Separated Bike Lane and Right Turn Lane
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2-42 DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
Figure 9 - Typical Layout of One-way Separated Bike Lane and Right Turn Lane
Notes:
1. Design plans should be consulted for variations
2. Vertical elements may be excluded or modified as needed to accommodate truck and/or
transit vehicles
3. 25' minimum where high bus volume is anticipated
4. 13' minimum where high bus volume is anticipated
5. Bike lane tapers preferred at 7:1 shift, minimum 3:1 shift in constrained locations where
speed is ≤ 13 mph
6. See city of boulder design and construction standards, section 2.07, table 2.5 for standard
lane widths
7. A ramp up to sidewalk may be provided for people on bicycles prior to vehicular mixing
zone to provide a low stress alternative
(F) Off-Street Multi-Use Paths
Design for off-street multi-use paths shall conform to Chapter 5 of the AASHTO Guide for the
Development of Bicycle Facilities, 4th edition. The paths shall be at least 10 feet wide with an
inside edge radius of at least 15 feet and shall conform to "Technical Drawing 2.02D," Chapter
11, of these Standards.
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(G) Bicycle Parking
Bicycle parking should be located in a visible and prominent location that is lit at night and
physically separated from automobile parking to prevent vehicles from intruding into the bike
parking area. All bicycle parking constructed in the City of Boulder shall conform to the
provisions in the Section 9-9-6(g), “Bicycle Parking,” B.R.C. 1981 or as adopted in any
subcommunity or area improvement plan.
(1) Bicycle Parking in Sidewalk Area of Public Right-of-Way: Bicycle parking racks
located in the sidewalk area of the public right-of-way shall be designed using either the
inverted “U” rack standard or the inverted “U” racks on rails standard. A minimum aisle of
5 feet shall be provided for bikes to maneuver in when accessing the rack. All racks shall
be attached to a concrete base using a high security tamper proof anchor such as a
mushroom head carbon steel expansion anchor “spike” #5550 as manufactured by Rawl or
an equivalent theft-proof device.
(a) Inverted “U” Rack: The inverted U rack is designed to park two bicycles, facing
opposite directions, parallel to the rack. For the rack to meet its design
specification of parking two bikes, it must be installed according to the
specifications below, otherwise it will be considered to provide parking for one
bike. The inverted “U” standard may be installed with the following conditions:
(i) Where the “U” rack is installed oriented parallel to a wall or curb, at least
3.0 feet shall be provided between the parallel wall or curb and the center
of the rack. Where a bike rack is located near a curb with “head-in”
automobile parking, a minimum distance of 5 feet from the curb to the
center of the rack is required to avoid damage to bicycles or racks by
automobiles extending across the curb over the sidewalk.
(ii) Where the “U” rack is installed oriented perpendicular to a wall or curb, a
minimum distance of 4 feet from the wall or curb to the center of the rack
will be provided to allow two bikes to access and use the rack.
(iii) Where placed side-by-side, “U” racks shall be placed at least 3.5 feet apart
to accommodate ease of access to the racks.
(iv) Where placed in a series of 2 or more and parallel to a wall, inverted “U”
racks will be separated by a minimum distance of 10 feet between the
centers of the racks to allow access to both sides of the rack.
(v) The location of a bike rack shall maintain a minimum unobstructed
sidewalk width of 6 feet from any bicycle parked properly in the rack.
(vi) The location of a “U” rack shall maintain a minimum unobstructed
distance of 3 feet from any pedestrian curb ramp to any bicycle parked
properly in the rack.
(b) Inverted “U” Racks on Rails: The inverted “U” racks on rails are designed to
park four to ten bicycles, with two bikes facing opposite directions parked on
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either side and parallel to each inverted “U” rack. These racks allow locking of
frame and wheel with a U-lock and support bikes with two points of contact. For
the rack to meet its design specifications of parking bikes from both sides, it must
be installed according to the conditions of the inverted “U” rack listed above;
otherwise it will be considered to provide no more than half of its designed
parking capacity.
(2) Onsite Bicycle Parking: Bicycle parking should generally be provided within 50 feet of
the main building entrance. Racks must be installed according to the guidelines in (1) above
to reach their designed parking capacity. Otherwise, they shall be credited with no more
than half their design capacity. Bicycle parking racks or lockers located on development or
project sites or in parking lots outside of public right-of-way shall generally be selected
from the following standards:
(a) Inverted “U” Rack: The inverted “U” rack is recommended for most bike rack
installations and is one of the standards for bicycle parking in public rights-of-way as
required in Subsection (1) above. Each rack provides space for two bicycles and
allows flexibility in parking by providing two supports for attaching locks. The “U”
rack may be used individually where space is limited, or, in circumstances requiring a
larger amount of bike parking, inverted “U” racks on rails may be used to park four
to ten bikes. Inverted “U” racks and inverted “U” racks on rails shall meet the
specifications for the dimensions and installation shown in Chapter 11, “Technical
Drawings,” of these Standards
(b) Other Bike Rack Styles: Another rack style may be approved by the Director of
Public Works if it meets the following criteria:
(i) Provides at least two contact points between the rack and the bike to
securely support the bike;
(ii) Provides at least a 2 foot by 6 foot parking space for each bike without the
need to lift the handlebars of one bike over those of another to park;
(iii) Allows the frame and one wheel to be locked to the rack with a standard
high security, U-shaped shackle lock; and
(iv) The rack is uncomplicated and intuitively simple for the bicyclist to use.
(c) Lockers: Bicycle lockers provide secure weatherproof storage for bike parking.
Lockers are recommended for employee and longer-term parking and require
adequate space, since they require more area than bicycle racks.
(3) On-Street Bike Parking (Bike Parking Corrals): The Director may approve on-street
bike corrals in commercial areas where sidewalk space is limited and in locations with high
pedestrian volumes. In approving the design and construction of bike corrals, the Director
shall consider public safety and the efficient operation of the City's transportation system.
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2.12 Street Lighting
(A) Scope
The provisions of this section shall apply to public streets, and are subject to the restrictions
outlined in the Section 9-9-16, “Lighting, Outdoor,” B.R.C. 1981.
(B) Guidelines for Street Lighting
(1) Street Light Requests
(a) Public Service Company (PSC) of Colorado is responsible for providing street
lighting as requested by the City.
(b) Before considering new or additional local street light requests, the City will
require unanimous consent of all affected owners of property within 100 feet of
proposed street light locations and the support of at least 51 percent of the total
number of owners of properties within 500 feet of proposed locations.
(2) Costs: The installation costs of street light fixtures, excluding those that provide a
demonstrated safety need, shall be paid by the applicant requesting the installation. The
City will assume continued maintenance and energy costs associated with new
installations.
(3) Priorities for Installation: Streetlights may be provided on the basis of identified traffic
need with priorities established as follows:
(a) Reduction of an identified night time traffic accident problem correctable through
street light installation.
(b) Major traffic corridors with significant turning movement conflicts and night
time pedestrian activity.
(c) Major traffic corridors with significant night-time turning movement conflicts.
(d) Arterial and collector intersections and/or horizontal or vertical alignment
changes.
(e) Residential street lighting.
(f) Commercial alleys with significant night-time pedestrian activity.
(4) Design: Street lights installed in public rights-of-way shall be an energy efficient
lighting source (LED unless otherwise approved by the Director) with a minimum of
ambient or reflected light (full cut-off fixtures). Poles shall be located so that the center
of the pole is three feet behind the face of the curb. The Director may approve a different
pole location that is between three feet and six feet behind the face of the curb where
necessary to accommodate the needs of other public right-of-way uses in the sidewalk
area. The City has adopted the Illuminating Engineering Society's (IES) American
National Standard Practice for Roadway Lighting as the design standard for all city
streets, with the following modifications:
(a) Expressway and Arterial: Street lighting shall be based on IES standards.
(b) Other Streets: Street lighting may be provided at intersections and identified
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pedestrian crossings only. Lighting may be considered at locations with
demonstrated needs based on changes in horizontal or vertical alignments.
Fixtures shall have 29-watt LED lighting unless street width or other conditions
justify higher wattage.
(c) Alleys: Except for alleys in commercial areas with significant night time
pedestrian activity, the city will not provide alley lighting.
(d) Private Driveways: Street lighting installed at the intersection of private
driveways and city streets shall be installed using City standards, be located
outside of the public right-of-way, and all costs for installation, maintenance, and
continued energy expenditures shall be the responsibility of the applicant
requesting the lighting installation.
(C) Easements
Adequate rights-of-way or utility easements shall be dedicated to the City to allow PSC of
Colorado to install street lights. Facilities with detached bike paths or sidewalks may use a
combined signage, utility, and pedestrian easement for placement of the street lights between the
curb and bikeway provided that the requirement for 2 feet of horizontal clearance from the
sidewalk or bike path is met. Where a bike path or sidewalk is attached to the street curb and
gutter, street lights shall be placed behind the sidewalk or path within a minimum 3-foot wide
utility easement. Utility easements for street lights are not exclusive, and may be landscaped or
used for parking subject to City approval. If there is an exclusive gas easement behind an
attached walk or path, the street lights shall be located beyond that easement in an additional
three-foot wide easement or the gas easement shall be relocated.
2.13 Transit Stop Facilities
New transit stops and enhancements to existing transit stops shall be designed in accordance with RTD's
"Bus Infrastructure Standard Drawings" and with consideration of NACTO's "Transit Street Design
Guide."
2.14 Traffic Calming Design
(A) Scope
XxxxxThe City endorses traffic calming elements in conformance with the Manual of Uniform
Traffic Control devices and in pursuit of achieving the goals identified in the most recently
approved Vision Zero Action Plan. Following sections include traffic calming devices currently
recommended to achieve vehicle speed and volume reduction goals.
(B) Neighborhood Traffic Circle
Xxxxx The following figures conceptually describe traffic circles to be constructed for traffic
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Effective: February 6, 2020TBD DESIGN AND CONSTRUCTION STANDARDS 2-47
calming at the discretion of the Principal Traffic EngineerDirector.
Figure 10 – Typical Layout and Standard Dimensions of Neighborhood Traffic Circle
Table 1. Offset and Opening Width Dimensions
Offset Opening Width
5.5’ (Max) 16’ (Min)
5.0’ 17’
4.5’ 18’
4.0’ 19’
3.5’ or less 20’ (Max)
Table 2. Center Island Diameter Dimension for Different Street Widths and Curb Return Radii
A
Street Width
B
Curb Return
Radius
C
Center Island
Diameter
28’
15’
20’
25’
18’
20’
22’
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2-48 DESIGN AND CONSTRUCTION STANDARDS Effective: February 6, 2020TBD
30’
15’
20’
25’
20’
22’
24’
36’
15’
20’
25’
27’
29’
33’
40’
15’
20’
25’
32’
34’
38’
Notes:
1. Use dimension schedule as a design guide. Final dimensions to be determined by the
engineer.
2. Where crossing streets are not the same width, consider curb extensions on wider street to
create consistent approach widths.
3. For locations with non-standard street widths, the relationship between the offset and the
opening width is determined by the opening width table.
4. Where the circulating width is less than 20 feet wide, a mountable truck apron may be
required.
5. Landscaping requires streets landscape architect review and approval. Plantings and trees
must not inhibit intersection sight distances by ensuring a clear zone of visibility between
36 inches high and 80 inches high from the pavement elevations.
6. Intersections with more or less than 4 legs require engineer approval.
(C) Raised Crossing
xxxx The following figures depict raised crossing details to be constructed at the discretion of
the Principal Traffic EngineerDirector. Raised crossings increase safety for bicycle and
pedestrian users at intersections and mid-block crossings by providing space that places their
movement priority above nearby vehicles at potential conflict points. Raised crossings also
strives to reduce vehicle speeds by installing a vertical deflection in the roadway profile which
creates safer interaction between bicycles/pedestrians and vehicles.
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Effective: February 6, 2020TBD DESIGN AND CONSTRUCTION STANDARDS 2-49
Figure 11 - Typical Layout of Raised Crossing at Mid-Block Location
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Figure 1212 - Typical Layout of Raised Crossing at Intersection Leg Location
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Effective: February 6, 2020TBD DESIGN AND CONSTRUCTION STANDARDS 2-51
Figure 1313 - Typical Layout of Raised Crossing at Channelized Right Turn Location
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Figure 1414 - Raised Crossing Typical Section and Notes
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Effective: February 6, 2020TBD DESIGN AND CONSTRUCTION STANDARDS 2-53
Table 3. Dimensions of Approach Ramp Length For Various Roadway Longitudinal Slopes and
Target Grade Breaks
Approach Ramp Length
Roadway
Longitudinal
Slope
5-6% Grade Break 8-10% Grade Break
Uphill Downhill Uphill Downhill
0% 5.0-5.5’
(3.0’-4.0’)
5.0-5.5’
(3.0’-4.0’)
3.0-3.5’
(2.0’-2.5’)
3.0-3.5’
(2.0’-2.5’)
2% 5.0-5.5’
(3.0’-4.0’)
5.0-5.5’
(3.0’-4.0’)
3.0-3.5’
(2.0’-2.5’)
3.0-3.5’
(2.0’-2.5’)
4% 5.0-5.5’
(3.0’-4.0’)
8.0-10.0’
(6.5’-7.5’)
3.0-3.5’
(2.0’-2.5’)
5.0’-6.0’
(4.0’-5.0’)
6% 5.0-5.5’
(3.0’-4.0’)
11.0-13.5’
(9.5’-11.5’)
3.0-3.5’
(2.0’-2.5’)
6.5’-8.5’
(5.5’-7.0’)
Note: Primary ramp lengths assume a 6-inch tall raised crossing. Ramp lengths in parenthesis assume
a 4-inch tall raised crossing.
Table 4. Target Grade Breaks For Different Roadway Classifications
Roadway
Classification
Grade Break Range
Min Max
Local 8% 10%
Collector 5% 6%
Arterial 5% 6%
Notes:
1. The width of the top of raised crosswalks should match the width of the connecting
sidewalk, shared use path, or desired crosswalk, but not less than 10' in width.
2. Modifications to existing street paving, cold plane and overlay asphalt, or reconstruction
of paving required as necessary to restore a smooth transition and street crown, match
paving materials and thickness, and warp new gutter to join invert at inlet.
3. Where positive drainage cannot be achieved, install supplemental drain inlet and connect
to existing stormwater conveyance system.
4. Place crosswalk 2' (min) from poles, hydrants, or other vertical obstructions.
5. Crosswalk cross slopes should be no greater than 2%, however, at mid-block locations
the cross slope may match the existing street grade. Cross slope may be 0% if
longitudinal slope is sufficient to self drain
6. Crosswalk longitudinal slope should not exceed 5%
7. Grade breaks should be determined based on existing roadway speeds and desired speed
reduction, generally higher grade breaks corresponds to higher speed reduction
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Effective: November 16, 2000 TBD DESIGN AND CONSTRUCTION STANDARDS 3-i
CITY OF BOULDER
DESIGN AND CONSTRUCTION STANDARDS
CHAPTER 3
STREETSCAPE DESIGN AND TREE PROTECTION
TABLE OF CONTENTS
Section Page
3.01 GENERAL ........................................................................................................................................................ 1
(A) INTENT ............................................................................................................................................................. 1
(B) SCOPE .............................................................................................................................................................. 1
(C) REFERENCE STANDARDS .................................................................................................................................. 1
(D) CITY APPROVAL REQUIRED ............................................................................................................................. 1
3.02 LANDSCAPING PLAN ....................................................................................................................................... 1
(A) LANDSCAPING PLAN REQUIRED ....................................................................................................................... 1
(B) TREE PROTECTION ........................................................................................................................................... 1
(C) LANDSCAPING PLAN REQUIREMENTS .............................................................................................................. 2
3.03 STREET TREES AND PLANTS .......................................................................................................................... 2
(A) TREE SELECTION .............................................................................................................................................. 2
(B) TREE PLACEMENT IN NON-PAVED MEDIANS AND LANDSCAPE PLANTING STRIPS ........................................... 5
(C) TREE PLACEMENT IN PAVED AREAS USING TREE GRATES AND PLANTING PITS .............................................. 6
(D) PLANT SELECTION AND PLACEMENT FOR LANDSCAPING IN MEDIANS ............................................................. 8
3.04 TREE REMOVAL AND RELOCATION ............................................................................................................... 9
(A) PERMIT REQUIRED FOR TREE REMOVAL OR RELOCATION ............................................................................... 9
(B) UNDESIRABLE TREES FOR PUBLIC RIGHTS- OF- WAY .................................................................................. 910
(C) TREE REMOVAL ............................................................................................................................................. 10
(D) TREE RELOCATION (TRANSPLANTING) .......................................................................................................... 10
3.05 TREE PROTECTION FOR CONSTRUCTION SITES ..................................................................................... 1011
(A) TREE PROTECTION REQUIRED .................................................................................................................... 1011
(B) TREE PROTECTION PROCEDURES ................................................................................................................... 11
3.06 GENERAL LANDSCAPING AND MAINTENANCE REQUIREMENTS ................................................................. 14
(A) PROTECTING EXISTING IMPROVEMENTS ........................................................................................................ 14
(B) MAINTENANCE OF LANDSCAPING .................................................................................................................. 14
LIST OF TABLES
Number Page
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Table 3-1: Approved Street Tree List for Non-paved Medians and Landscape Planting Strips ................................ 44
Table 3-2: Limitations on Individual Tree Species ....................................................................................................... 5
Table 3-3: Tree Grates and Planting Pits Standards ..................................................................................................... 6
Table 3-4: Approved Street Tree List for Paved Areas Using Tree Grates and Planting Pits……………………..….7
Table 3-5: Approved Median Shrub List .................................................................................................................... 89
Table 3-6: Tree
Characteristics………………………………………………………………………………….……15
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Effective: November 16, 2000 TBD DESIGN AND CONSTRUCTION STANDARDS 3-1
3.01 General
(A) Intent
The Streetscape Design and Tree Protection Standards are intended to improve public safety by
preventing sight distance and facility obstructions and sidewalk and street damage, to promotepromoting
suitable landscape species selection for streetscapes, to minimizeminimizing tree and landscape
maintenance costs.
(B) Scope
These Standards apply to public and private streetscapes and private construction sites where
specifiedcontaining existing trees proposed for preservation, and include the planting, maintenance,
pruning and spraying, protection and removal of trees and landscaping materials located, standing, or
growing within or upon any City of Boulder public right- of- way. Tree Protection standards also apply
to private construction sites containing to any existing private trees proposed for preservation as a part of
a development approval under Title 9 pf the B.R.C. 1981. The requirements of this chapter are in addition
to and compliment complement those set forth in Chapter 10, “Streetscaping Landscape Standards,” and
applicable streetscape drawings in Chapter 11, “Technical Drawings,” of these Standards and the B.R.C.
1981.
(C) Reference Standards
Where not specified in these Standards or the B.R.C. 1981, in order to protect the public health, safety,
and welfare, the Director of Public Works in consultation with the Director of Parks and Recreation will
specify the standards to be applied to the design and construction of streetscapes public landscapes and
the planting of trees, and may refer to one or more of the references listed in the References Section of
these Standards.
(D) City Approval Required
All work associated with the planting, maintenance, and removal of trees and landscaping materials
located, standing, or growing within or upon any City of Boulder public right - of- way is subject to City
of Boulder approval or permit issuance as set forth in Chapter 8-5, “Work in the Public Right - of- Way
and Public Easements,” and Chapter 6--6, “Protection of Trees and Plants,” B.R.C. 1981.
3.02 Landscaping Plan
(A) Landscaping Plan Required
An applicant for construction approval involving a project or development where streetscaping
improvements are to be provided or potentially impacted by the installation or construction of public
improvements, or where prescribed by a City adopted subcommunity, area, or special improvement plan,
shall submit a Landscaping Plan in compliance with these Standards and those set forth in Chapter 6---6,
“Protection of Trees and Plants,” Chapter 9-3.39, “Site Development Standards,” andand Chapter 9-125,
“Subdivisions,” B.R.C. 1981. Coordination to meet any applicable requirements of ChapterTitle 9 shall
be the responsibility of the developer/owner.
(B) Tree Protection
The Landscaping Plan shall include design details and notes, construction activity controls and measures,
and any necessary provisions or restrictions to ensure the protection of existing trees as required in
Chapter 6-6, “Protection of Trees and Plants,” B.R.C. 1981, and Section 3.05, “Tree Protection for
Construction Sites,” of these Standards. For large or complicated sitesprojects larger than one single
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3-2 DESIGN AND CONSTRUCTION STANDARDS Effective: November 16, 2000TBD
family dwelling, a separate Tree Protection Plan in addition to the required Landscaping Plan shall be
required. The city may require tree protectionAll tree protection shall to be installed and monitored by a
certified arborist.
(C) Landscaping Plan Requirements
The Landscaping Plan shall be prepared in compliance with the requirements in Section 1.03, “Submittal
Requirements for Construction Approval,” of these Standards, Section 9-9-12 B.R.C. 1981 and shall
include but are not limited to the following elements:
(1) Location, typespecies, and size of all existing trees and landscaping materials, and
identification of any required tree protection measures as outlined in Section 3.02(B),
“Tree Protection.” of these Standards.
(2) Design location, typespecies, and size of all trees and landscaping materials proposed to
be planted, removed, or relocated.
(3) Location of existing and proposed public utilities and transportation improvements and
public rights- of- way boundaries.
(4) When a drainage report is required in accordance with Chapter 7 of these standards, the
landscape plan shall display drainage flow arrows and the location of open channels,
storm inlets, and stormwater control measures to indicate the interaction between
plantings and drainage."Indication of how site grading and consequent drainage flow
interacts with location of plantings. And existing trees?
(45) Specifications and construction notes for proposed trees and landscaping materials,
including without limitation, plant variety types, number and size of plants to be installed,
location, sizing, and design details for irrigation systems, planting and maintenance
requirements for specific species, tree protection systems and measures , and tree grate
type and installation details. Specifications and construction notes for proposed tree
3.03 Street Trees and Plants
(A) Tree Selection
(1) Trees proposed to be planted in non-paved public rights - of- way shall be selected from
Table 31, “Approved Street- Tree List List for Non-paved Medians and Landscape
Planting Strips,” unless an alternative tree selection has been reviewed with the Director
of Parks and Recreation and approved by a Cityadopted subcommunity, area or special
improvement planthe City of BoulderCity Managerthe Director. Other species and
varieties of trees may be used, subject to City approval. Alternative species and varieties
should be thornless, cottonless, minimally fruiting, minimally seeding, and single-stem,
tree-form varieties.
(2) Tree species that are not to be placed in public rights- of- way include: Ash, Box Elder,
Cottonwood, Chinese and Siberian Elm, Poplar, Russian Olive, Silver and Norway
Maples, Tree of Heaven, Willow, evergreens that create sight obstructions, and clump
forms or multistem trees.
(32) Trees to be planted in non-paved medians or landscape planting strips shall be
selected using the minimum planting strip width requirements for the tree species listed
in the Forestry a”Approved Tree List” table Table 31 for the available planting strip
width.
(4) Trees selected for narrow (4’-5’) planting strips must be upright forms of tree
species under the small tree category. Upright varieties of tree species such as crabapple
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Effective: November 16, 2000 TBD DESIGN AND CONSTRUCTION STANDARDS 3-3
(‘Centurion’ and ‘Red Barron’) and pear (‘Chanticleer’) are recommended for a 4’-5’
planting strip along arterial streets where a high volume of traffic is a concern. Other
crabapple varieties can be planted in a 4’-5’ planting strip along non-arterial streets or in
a 6’-7’ planting strip.
(53) Trees shall not be planted in planting strips that are less than 4 feet in width wide or
where the planting strip is narrower than the required minimum planting strip width for
specific tree species.
NOTE: For detached sidewalk landscaped planting strips, the planting strip width is
measured from the back edge of curb to the front edge of the sidewalk.
(64) Evergreen trees shall not be selected for placement in public rights - of- way medians or
landscaping strips, due to the potential for overcrowding, and sight obstructions and
icing, unless these concerns can be mitigated and adequate planting strips at least 20 feet
wide are provided.
Deciduous conifers such as baldcypress or dawn redwood are allowed in 8’ + planting strips.
(75) Whenever possible, trees should be selected from species noted as having “drought
tolerant”xeric or minimum moisture level requirements as noted in the “Approved Tree
List” in consultation with the city forester in Table 31.
(86) A variety of trees, as required in Table 3-21, “Limitations on Individual Tree Species,”
shall be selected for planting within any given site or street corridor, including street
medians and curbside landscape strips, to prevent uniform insect or disease susceptibility
associated with planting a single genus or species. A maximum of 3 plantings of the same
tree species type are allowed planted in a row.
(97) Trees proposed for the public rights- of- way in the Downtown Area shall follow the
guidelines outlined in the most current adopted version of the Downtown Urban Design
Guidelines, 199920022016.
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Table 3-1: Approved Street Tree List for Non-paved Medians and Landscape Planting Strips
Trees on the following list will do well in our local environment provided the appropriate species is selected for a particular site. (see Table 3-6,
“Tree Characteristics”) The trees on this list offer a wide range of varieties and cultivars which fit into local landscapes. Tree names are
followed by examples of acceptable tree varieties that may be used in streetscapes. Other available varieties of each tree type may be used,
subject to City approval, if they are thornless, cottonless, minimally fruiting, minimally seeding, and tree-form varieties. Trees are listed in
alphabetical order and are not prioritized according to their suggested use.
Small Maturing Trees
(Under 25' Mature Height)
Required Planting Strip Width
4'-5' Minimum
Spacing Between Trees
15' Minimum, 20' Recommended
Medium Maturing Trees
(30'-45' Mature Height)
Required Planting Strip Width
6'-7' Minimum
Spacing Between Trees
25' Minimum, 30' Recommended
Large Maturing Trees
(Over 45' Mature Height)
Required Planting Strip Width
8' Minimum
Spacing Between Trees
30' Minimum, 40' Recommended
Crabapple- Malus spp. (Fireblight resistant
varieties, inc. ‘Centurion,’ ‘Red Barron’)
Cherry - Prunus sargentii (Sargent)
Ash, Green1,2 - Fraxinus pennsylvanica
(‘Marshall’s Seedless,’ ‘Newport,’
‘Patmore,’)
Goldenraintree1 - Koelreuteria paniculata
Crabapple- Malus spp. (Fireblight resistant
varieties, inc. ‘Indian Magic’, ‘Indian
Summer’, ‘Radiant’, ‘Spring Snow’)
Ash, White2 - Fraxinus americana (‘Autumn
Applause,’ ‘Autumn Purple,’ ‘Rosehill’)
Hawthorn - Crataegus spp. (thornless cockspur,
‘Ohio Pioneer’) Tree Form
Hackberry, Common1 - Celtis occidentalis
(‘Prairie Pride’)
Baldcypress - Taxodium distichum
Lilac, Japanese tree- Syringa reticulata Tree
Form
Honeylocust1 - Gleditsia triacanthos var.
inermis (‘Imperial,’ ‘Sunburst’)
Catalpa, Western1 - Catalpa speciosa
Maple, Amur1 - Acer ginnala Tree
Form
Hop Hornbeam - Ostrya virginiana
Coffeetree, Kentucky1 - Gymnocladus dioicus
Maple, Norway - Acer platanoides (‘Crimson
Sentry’)
Hornbeam, European - Carpinus betulus
Elm, American - Ulmus americana
(‘Brandon,’ ‘Valley Forge’)
Maple, Tatarian - Acer tataricum Tree
Form
Linden, Littleleaf - Tilia cordata
(‘Corinthian’)
Hackberry, Common1 - Celtis occidentalis
Oak, Gambel - Quercus gambelii Tree
Form
Maple, Norway - Acer platanoides
(‘Cavalier,’ ‘Drummondi’)
Honeylocust1 - Gleditsia triacanthos var.
inermis (‘Shademaster,’ ‘Majestic’)
Pear - Pyrus calleryana ‘Chanticleer’
Maple, Hedge - Acer campestre
Horsechestnut, Common - Aesculus
hippocastanum
Prunus - Prunus spp. (Cherries, Plums,
Almonds, Apricot1) Tree Form
Maple, Wasatch1 - Acer grandidentatum
Tree Form
Linden, American - Tilia americana
(‘Legend’, ‘Redmond’)
Redbud - Cercis canadensis Tree
Form
Ohio Buckeye1 - Aesculus glabra
Linden, Littleleaf - Tilia cordata
(‘Chancellor,’ ‘Greenspire’)
Serviceberry - Amelanchier spp. Tree
Form
Pear - Pyrus spp. (Ussurian, Callery - avoid
‘Bradford’ variety)
Maple, Norway - Acer platanoides
(‘Deborah,’ ‘Emerald Queen’)
Turkish Filbert - Corylus colurna
Maple, Red - Acer rubrum (‘Northwood’,
‘Red Sunset’)
Maple, Sugar - Acer saccharum (‘Green
Mountain’, ‘Legacy’)
Oak - Quercus spp. (Bur1, English, Red,
Shumard, Swamp White1)
1 Indicates drought-tolerant species.
2 Green/White ash should be used sparingly and not in large rows or groupings because of major problems with brownheaded ash sawfly and
lilac/ash borer.
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Effective: November 16, 2000 TBD DESIGN AND CONSTRUCTION STANDARDS 3-5
Table 3-1: Limitations on Individual Tree Species
(The following table applies to all genus and species unless otherwise approved by the City ForesterManagerDirector)
Number of Trees in the Site or Corridor Maximum Percentage of Any Genus or Species
≤3 100% Genus
4 to 8 50% Genus
9 to 15 33% Genus
16 to 50 20% Species, 30% Genus
≥51 10% Species, 20% Genus
Note: Any exceptions to the above diversity percentages must be approved by the City Manager. Tree availability at the
time of construction may impact tree diversity requirements. Genus and species substitutes, as well as revisions to tree
diversity requirements will be reviewed on a project by project basis by the City Manager.
Table 3-21: Limitations on Individual Tree Species
(The following table applies to trees in both Table 3-1 and Table 3-4all genus and species unless otherwise approved by the
City Foresterstaff.)
Number of Trees in the Site or Corridor Maximum Percentage of Any OneGenus or Species
10-19 5033%
20-39 2533%
40 and Over 1525%
(B) Tree Placement in Non-paved Medians and Landscape Planting Strips
(1) Tree placement of deciduous and evergreen trees shall be designed and based on the
expected mature height and canopy spread for the selected species, to prevent
unnecessary competition or overcrowding of trees.
(2) Trees shall not be placed where the expected mature height and canopy spread could
obstruct sight distance of any public sign, driveway, alley, or intersection, as set forth in
Section 9-3.3-59-7, “Sight DistanceTriangles,” B.R.C. 1981, or where the physical
obstruction of any sidewalk, trail, alley, or street lane could occur.
(3) New or transplanted trees shall not be placed within 10 feet of existing underground
water, sewer, or storm water utility lines. New underground utilities should not be placed
within 10 feet of existing trees without the prior review and approval of the Director.
(4) Trees shall not be placed within 20 10 feet of any utility pole, streetlight or pedestal.
When tree placement is allowed under overhead power utility lines, only those tree
species listed as “Small Maturing Trees” on the “Approved Tree List”on Table 31,
“Approved Street Tree List,” shall be planted.
(5) Trees shall not be placed within 15 feet of any ditch embankment and ditch company
owners should be consulted prior to any tree planting adjacent towithin the ditch
easements.
(56) Trees should shall be located at least 10 feet away from buildings and offset from
building entrances. When available space is limited, only species with columnshaped
columnar or pyramidshaped fastigiate forms shall be planted.
(67) Trees may shall be planted in right-of-way landscape planting strips adjacent to existing
trees on private property only when all trees have enough space to grow to their expected
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3-6 DESIGN AND CONSTRUCTION STANDARDS Effective: November 16, 2000TBD
mature size. Trees with narrow forms should be used in the right-of-way when there is
the potential for overcrowding with existing trees.
(78) Trees shall be planted in the center of right- of- way planting strips, or appropriately
placed for mature height and spread, to ensure tree health, prevent root damage to
sidewalks and street facilities and to avoid a sight distance obstruction.
(89) Trees shall not be placed in medians or landscape planting strips less than 4 feet wide or
where the planting strip is narrower than the required minimum planting strip width for
specific tree species as listed in Table 3-1, “Approved Street Tree List for Non-paved
Medians and Landscape Planting Strips.”
NOTE: For detached sidewalk landscaped planting strips, the planting strip width is
measured from the back edge of curb to the front edge of the sidewalk.
(910) Evergreen trees shall be placed at least 10 feet behind the edge of pavement, curbs or
sidewalks, or far enough to permit clearance of the tree’s mature canopy spread if
previously approved by the City.
(1011) Evergreens shall not be placed on the south sides of east-west running streets.
(118) Deciduous tTrees shall not be placed in the right- of- way where the planting strip behind
an attached sidewalk, edge of pavement, or curb along roadways without sidewalks
extends less than 4 feet to the property line from the back edge of the an attached
sidewalk, edge of pavement, or curb to the property line. In such cases, street trees shall
be planted on adjacent private property.
(129) Tree spacing for trees placed in landscaped planting strips shall comply with the
“Spacing Between Trees” requirements listed in the species headings in Table 3-21,
“Approved Street Tree List for Non-paved Medians and Landscape Planting Strips.”
Tree placement should meet the recommended tree spacing and shall not be less than the
minimum tree spacing requirements unless previously approved by the CityDirector.
(13)
(C) Tree Placement in Paved Areas Using Tree Grates and Planting Pits
(1) Trees using tTrees within grates and planting pits shall be placed in compliance with the
design standards for tree spacing and shall generally be planted in a 4 ft. x 10 ft. two
piece Neenah Foundry, or approved equal, grate unless otherwise approved through a
variance request. Tree spacing for tree grates shall comply with the “Spacing Between
Trees” requirements listed in the species headings in Table 32, “Approved Street Tree
List.”
Table 3-3: Tree Grates and Planting Pits Standards
Tree Species Size
Tree Spacing
Minimum Tree Grate
Area
(Width x Length)
Minimum SoilTree Pit
Volume*
(Width x Length x Depth)
Small Tree
150 Ft. minimum,
15 Ft. recommended
20 Sq. Ft. minimum,
4 Ft. min. width
(Ex. 4 ft. x 5 ft.)
600 Cu. Ft. minimum,
3 Ft. min. depth
(Ex. 4 ft. x 5 ft. x 3 ft.)
Medium Tree
2515 Ft. minimum,
20 Ft. recommended
32 Sq. Ft. minimum,
4 Ft. min. width
(Ex. 4 ft. x 8 ft.)
9006 Cu. Ft. minimum,
3 Ft. min. depth
(Ex. 4 ft. x 8 ft. x 3 ft.)
Large Tree
3020 Ft. minimum,
40 Sq. Ft. minimum,
1200 Cu. Ft. minimum,
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Effective: November 16, 2000 TBD DESIGN AND CONSTRUCTION STANDARDS 3-7
25 Ft. recommended 4 Ft. min. width
(Ex. 4 ft. x 10 ft.)
3 Ft. min. depth
(Ex. 4 ft. x 10 ft. x 3 ft.)
* Where soil volumes between trees overlap, up to 25% of the required soil volume per tree may be
shared.
(2) Tree grates, tree guards and planting pits shall be provided in locations where a hard
surface or paved area is required to adequately accommodate pedestrians, including
without limitation downtown or commercial sidewalks, malls, and plazas. The tree grate
allows air and moisture to reach tree roots and limits compaction of the soil around the
tree to maintain healthy growth.
(3) Trees using within tree grates shall not be placed where the expected mature height and
canopy spread could obstructs sight distance of any public sign, driveway, alley, or
intersection, as set forth in Section 9-3.359-7, “Sight DistanceTriangle,” B.R.C. 1981, or
where the physical obstruction of any sidewalk, trail, alley, or street lane could occur.
(4) Trees using within tree grates shall not be placed within 10 feet of any existing
underground water, sewer, or storm water utility line or within 20 10 feet of any utility
poles or pedestal. When tree placement is allowed under overhead power utility lines,
only those tree species listed as “Small Maturing Trees” ion Table 3-42,on the
“Approved Street Tree List for Paved Areas Using Tree Grates and Planting Pits,” shall
be planted.
(5) Trees using within tree grates should be located at least 10 feet away from buildings and
offset from building entrances. When available space is limited, only species with
column-shaped or pyramid-shaped forms shall be planted.
NOTE: that below grade parking structures are considered buildings and must meet this
requirement.
(6) Adequate growing space between the tree trunk and first ring of the tree grate shall be
provided to allow the tree to grow properly without girdling. The opening in the center
of the tree grate through which the tree grows shall provide 4-6 inches of clearance from
the tree trunk and be at least 182 inches in diameter. The tree shall be centered within the
tree grate opening.
(7) If large-area tree grates are not available or cannot be used, the required permeable
surface area may be provided by using multiple tree grates that are at least 4 feet wide, or
by providing a single tree grate around the tree trunk that is at least 4 feet wide in
conjunction with natural permeable materials, such as landscaping pavers, over the
remainder of the planting pit surface. Any non-standard tree grate frame installation shall
have adequate structural support and be approved by the Director.
(8)(7) The soil surface within a planting pit and beneath a tree grate shall be level with the
bottom of the sidewalk slab. This is to avoid problems with root flares lifting grates as
the tree grows and allows the roots to find air and water. Trees are then to be planted so
that the top of the root ball is 2” above the finished grade of the soil.
(9)(8) Planting pits shall be 3 feet deep and have the same surface area as the required tree grate
area, and may not be deepened unless warranted by the depth of the root ball of the tree
to be planted. A planting pit shall not be deepened to increase pit volume as an
alternative to providing the minimum tree grate surface area.
(10) The growth of trees using tree grates shall be monitored to ensure that inner grate rings or
the entire tree grate is removed as necessary to prevent girdling the tree.
(11)(9) Tree grates shall be flush with the finish grade of adjacent pavement final surface grades.
(12)(10) All tree grates shall be installed per the manufacturer’s specifications. Grates
shall be supported by a frame which has anchors embedded in the surrounding concrete.
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3-8 DESIGN AND CONSTRUCTION STANDARDS Effective: November 16, 2000TBD
Final frame dimensions shall be 1/16 to 1/8-inch larger than the grate dimension on all
sides to allow the grate to drop into the frame seat. Frame sections are to be bolted
together and cast into the surrounding concrete. Frames must be level and the seat for the
grate must be in a true, flat, plane to prevent rocking of the grate. The seat for the grate
shall be cleaned prior to setting the grate. To ensure proper fit, the grate or a template
should shall be placed in the frame before concrete is poured so that the final installation
will be square and level.
(13)(11) Tree grates are to be of the pedestrian safe style with slot openings 3/8-inch in
width or less and designed to accommodate a tree guard.
Any grate installed flush to the curb shall be truck rated to avoid breakage or shall be
installed a minimum of 182 inches from back of curb.
(12) Tree guards shall have 5’ with either an 18” opening to match the tree grate and shall be
installed per the manufacturer’s specifications.
(D) Plant Selection and Placement for Landscaping in Medians
(1) Plants proposed to be planted in medians in the public right-of-way shall be selected from
Table 3-1, “Approved Street Tree List for Non-paved Medians and Landscape Planting
Strips, or Table 3-4, “Approved Street Tree List for Paved Areas Using Tree Grates and
Planting Pits,” or Table 3-5, “Approved Median Shrub List,” unless an alternative plant
selection has been approved by a City-adopted subcommunity, area or special
improvement plan.the City
(2) Median plants selection and placement shall be designed and based on the expected
mature height and spread of the selected species, to prevent unnecessary competition or
overcrowding of plants and to ensure that the selected mature plants remain within the
median width without requiring excessive or frequent pruning.
(3) Median plants shall not be placed where the expected mature height and spread could
obstruct sight distance of any public sign, intersection, or crosswalk as set forth in
Section 9-3.3-59-7, “Sight DistanceTriangles,” B.R.C. 1981.
(4) Plant species that are not well-suited for median environments and should not be placed
in medians in the public right-of-way include: Junipers (select species including `Blue
Pfitzer’, `Blue Rug’, `Calgary Carpet’, `Pfitzers’, `Sea Green’, and `Tam’) Bridal Wreath
Spirea, Flowering Crabs, Forsythia, Ginnala Maple, Honeysuckle, Pyracantha, and
Redtwig Dogwood.
Table 3-5: Approved Median Shrub List
Amorpha, var. (‘Leadplant,’ ‘Indigo Bush,’ etc.)* Mountain Mohagany*
Apache Plume - Fallugia paradoxa* Potentilla – Potentilla fruticosa
Artemisia (‘Powis Castle’)* Prunus besseyi, tenella*
Barberry Rabbitbrush* - Chrysothamnus nauseosus
Cliffrose, Mexican - Cowania mexicana* Sage, Russian – Perovskia atriplicifolia*
Cotoneaster (various) Sagebrush* - Artemisia sp. (‘Big,’ ‘Sand’)
Cranberrybush - Virburnum opulus (‘Compactum’) Serviceberry – Amelanchier alnifolia*
Fernbush - Chamaebatiaria millefolium Shrub Rose (various)
Juniper (‘Arcadia,’ ‘Blue Chip,’ ‘Broadmoor,’ ‘Buffalo,’
‘Hughes,’ ‘Scandia’)
Snakeweed – Gutierrezia sarothrae*
Spirea (‘Bluemist*,’ bulmalda, ‘Mongolian’)
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Effective: November 16, 2000 TBD DESIGN AND CONSTRUCTION STANDARDS 3-9
Amorpha, var. (‘Leadplant,’ ‘Indigo Bush,’ etc.)* Mountain Mohagany*
Lilac* - (‘Dwarf,’ ‘Littleleaf’) Sumac* - Rhus aromatica (‘Grolow’)
* Indicates drought-tolerant species.
3.04 Tree Removal and Relocation
(A) Permit Required for Tree Removal or Relocation
(1) An applicant for construction approval shall not remove or relocate any tree existing
within any public right- of- way without first having a landscaping plan approved, and
obtaining a right- of- way permit per Chapter 8-5 “Work in the Public Right-of-way and
Public Easements,” B.R.C. 1981and authorization from the City Forester perpreapprovals
required in Chapter 6-6, “Protection of Trees and Plants,” B.R.C. 1981..
(2) An applicant for construction approval may not request City approval nor propose as part
of a landscaping plan for a project or development the removal or relocation of a tree in
the public right- of- way unless:
(a) The site cannot feasibly be developed, through design or construction
alternatives, without removing or relocating the tree, and the applicant mitigates
the loss of the tree,
(b) The tree is determined by the City to be undesirable as outlined in Section
3.04(B), “Undesirable Trees for Public Rights-of-Way,’ below, or
(c) The City is requiring the removal of a tree as part of construction approval.
(3) Where tree mitigation is required for tree removal per Chapter 6-6, “Protection of Trees
and Plants,” B.R.C. 1981., trees required to be planted as part of standard project or
development approval will not be counted towards the required mitigation.
(4) Mitigation shall be satisfied when all fees are paid and replacement trees are planted.
Mitigation fees are determined by the City ForesterManager Forestry Department and
due prior to issuance of building permits. If replacement is appropriate, a landscape plan
showing the location, species and size of all plant material shall be required.
(B) Undesirable Trees for Public Rights- of- Way
The City may determine that certain trees located within the public right - of- way are undesirable and
may recommend or require removal of these trees if:
(1) The trees are less than 1 inch in caliper, usually representing volunteer trees or suckers
that seldom conform to selection and placement standards, and are smaller than would be
required for new plantings.
(2) The trees are smaller than 12 inches in diameter and are listed as trees not to be placed in
the public right- of- way in Section 3.03(A)(2). Cottonwood (any Poplar species),
Siberian Elm, Russian Olive, Silver Maple, Tree-of-Heaven, Willow, evergreens that
create sight obstructions, and clump forms or multi-stem trees.
(3) Trees that have been severely damaged or are in poor general health, as determined by
the City under generally accepted forestry standards. This determination will not apply if
the damage or poor general health is the result of actions or inaction of the adjacent
property owner or the applicant for construction approval.Trees damaged or in poor
general health as the result of actions or inaction of the adjacent property owner requires
the loss be mitigated by such property owner perChapter 6-6, “Protection of Trees and
Plants,” B.R.C. 1981.
(4) Trees that, due to their species, location, or density would not conform to the existing
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3-10 DESIGN AND CONSTRUCTION STANDARDS Effective: November 16, 2000TBD
streetscape standards for tree placement or spacing as outlined in these Standards.
(C) Tree Removal
(1) Trees shall only be removed in compliance with a landscaping plan, approved by the City
as set forth in these Standards. Trees shall be deemed removed if greater than 40% of the
canopy or root system is damaged or removed during construction as determined by the
City ManagerDirector under generally accepted forestry standards.
(2) All trees to be removed shall be marked with an “X” in blue permanent marking and
approved by the City prior to removal.
(3) All tree removal shall include stump grinding to a minimum depth of 12 inches.
(D) Tree Relocation (Transplanting)
(1) Trees with a “transplanting ease” rating of 1 or a 2, as defined in the Tree and Shrub
Transplanting Manual, are considered eligible for transplanting, subject to City approval.
All transplanting shall be in a location approved by the City.
(2) Trees eligible for transplanting shall meet the following requirements:
(a) Be 8 inches or less in caliper, unless approved by the City, and
(b) Have a root ball size of 1 foot per 1 inch of trunk caliper, evenly distributed on
all sides from the center line of the trunk. For example, a tree with a 4-inch
caliper shall have a root ball with a 4-foot diameter, evenly distributed with 2 feet
on all sides from the centerline of the trunk.
(3) Transplanting shall be done only by an experienced tree professionala licensed arborist or
tree contractor per Chapter 4-28 B.R.C. 1981 and according to a landscaping plan
approved by the City.
(4) The applicant for construction approval shall ensure that the transplanted tree survives
without significant loss of tree value in compliance with the tree protection standards set
forth in Chapter 6-6, “Protection of Trees and Plants,” B.R.C. 1981.
(5) Transplanting periods:
(a) Transplanting shall be done between February 15December 1 and April 30 for all
trees, except for trees identified in the Tree and Shrub Transplanting Manual as
unsuitable for early spring transplanting.
(b) Trees identified as unsuitable for early spring transplanting shall be transplanted
only between September 15 and October 30.
3.05 Tree Protection For Construction Sites
(A) Tree Protection Required
(1) An applicant for construction approval shall protect trees and plants in the public
right- of- way and on any project or construction site where public improvements are
proposed.
(2) An applicant for construction approval shall submit a landscaping plan incorporating
proposed tree protection measures for any existing trees located in the public
right- of- way and on site at any project or construction site where public improvements
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Effective: November 16, 2000 TBD DESIGN AND CONSTRUCTION STANDARDS 3-11
are proposed in compliance with these Standards. For projects larger than one single
family dwellingFor large or complicated sites, a separate Tree Protection Plan in addition
to the required Landscaping Plan shall be required.
(3) The landscaping plan shall identify any potential detrimental effects to existing trees that
might result from proposed construction activities within 20 feet of the dripline of any
existing trees located on site or in the adjacent public right- of- way. The plan shall
include the species, size, and location of all existing trees that are 12-inch or larger
caliper size. If no existing trees are present that require protection, this shall be noted on
the Landscape pPlan. Existing trees approved to be removed or relocated shall be clearly
identified on the landscaping Llandscape/Tree pProtection Pplan.
(4) The applicant for construction approval shall notify the City within 24-hours of any
suspected damage to trees resulting from construction activities. If damage occurs during
construction, the applicant shall have the damaged tree restored evaluated immediately by
a City of Boulder licensed certified qualified arborist.
(5) If greater than 4250% of the canopy or root system is damaged or removed during
construction, the tree shall be evaluated for safety and future health by a City of Boulder
licensed certified the qualified arborist. A complete copy of the evaluation shall be
submitted to the City. Mitigation shall be required if the tree is unsafe and subsequently
removed.
(B) Tree Protection Procedures
(1) Protective Maintenance: An applicant for construction approval shall provide
maintenance and care for existing trees required to be protected on site and in the public
right- of- way adjacent to any project or construction site during construction activities
and the public improvement warranty period, Section 9-12-14 “Public Improvement
Warranty” B.R.C. 1981, to ensure that existing trees survive and are not damaged.
(92) Watering: For trees 1”-3” diameter water weekly at a rate of 10 gallons/inch of
diameter; for trees 4”-9” diameter water 3x per month at a rate of 10 gallons /inch
of diameter; for trees 10” diameter or larger apply water 2x per month at the rate
of 15 gallons / inch of diameter. The above schedule should be followed April –
September; for Oct – March apply water once per month.
(23) Soil Compaction Prevention
(a) To prevent soil compaction, designated routes for equipment and foot traffic by
work crews shall be determined prior to commencing construction activities and
indicated in the Llandscapeing/ Ttree Pprotection Pplan.
(b) These planned routes shall be marked at the site before construction commences
with durable fencing material that is at least 4 feet high. Flagging tape or any
other material that may be torn down, moved, or evaded is not acceptable.
(c) The contractor shall inform all construction crew members on the site of access
routes and will ensure that only these routes are used.
(d) To prevent tree root smothering, no soil stockpiles, supplies, equipment, portable
toilets, or any other material shall be placed or stored within a tree dripline or
within 15 feet of the tree trunk for columnshaped and evergreen trees, whichever
distance is greater.
(e) Soil around a tree dripline may be required to be aerated during and after
construction activities. This is necessary even when compaction results from
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3-12 DESIGN AND CONSTRUCTION STANDARDS Effective: November 16, 2000TBD
heavy foot traffic. A City of Boulder licensed certified professional arborist shall
perform do the vertical aeration or soil fracturing. SOoil fracturing techniques
comparable to using a “growgun” with Isolite material are acceptable.
Conventional turf aeration is not acceptable.
(f) When foot traffic or equipment use is unavoidable within the dripline, the area
within the dripline shall be mulched with wood chips to a depth of 6 inches
before construction activity begins. A 6inch6-inch mulch depth shall be
maintained for the duration of the project, then removed when construction
activities are completed.
(34) Root Protection
(a) Tree roots shall not be cut unless cutting is unavoidable.
(b) When root cutting is unavoidable, a clean, sharp cut shall be made to avoid
shredding or smashing. Root cuts should be made back to a lateral root.
(c) Root cutting shall only be performed by a licensed arborist.
(cd) Whenever possible, tree roots should be cut between late fall and bud opening,
when root energy supplies are high and conditions are least favorable for disease
causing agents.
(de) The City ForesterManager shall be notified of any cutting of the following roots:
(i) Two roots having a diameter of more than 3 inches, or
(ii) Four roots having diameters between 2 and 3 inches.
(ef) Trenches shall be hand dug within the dripline in areas where roots 2 inches and
larger in diameter are present, and when low branches which may be damaged by
equipment are present.
(fg) Whenever possible, roots 2 inches or larger in diameter shall be tunneled or
bored under and shall be covered to prevent dehydration. Exposed roots shall be
covered immediately with soil or burlap and kept moist.
(gh) Power tools shall not be used to prune roots, with the exception of
arboriculturally approved rootcutting- equipment used under the supervision of
the City. Only the following approved tools shall be acceptable: scissorstype
hand pruners and loppers, except -anviltypes, and -arboristtype- pruning saws.
(hi) When more than one root 2 inches or larger in diameter on any public tree is cut,
sSupplemental watering, in addition to section 3.05 B (2), shall be provided if the
tree lacks an operational sprinkler system. The applicant or abutting landowner
shall provide the watering. Watering shall commence immediately after roots
have been cut or damaged at the following rates:
i. 1”-3” diameter water weekly at a rate of 10 gallons/inch of diameter;
ii. 4”-9” diameter water 3x per month at a rate of 10 gallons /inch of
diameter;
iii. 10” diameter or larger apply water 2x per month at the rate of 15
gallons / inch of diameter.
The above schedule should be followed April – September; for Oct –
March apply water once per month following above amounts.
(ij) Sidewalk and paving surfaces shall be sufficiently contoured to avoid cutting
surface tree roots. Whenever possible, tree roots should be bridgeed or floated
over with walks.
(jk) To allow maximum aeration and water penetration to roots, walk materials other
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Effective: November 16, 2000 TBD DESIGN AND CONSTRUCTION STANDARDS 3-13
than concrete may be selected (e.g., brick, flagstone, honeycomb block, chips,
gravel) subject to City approval. Under no circumstances shall impervious
material make contact with or completely encircle a tree trunk.
(kl) Auger tunneling, not trenching, shall be used where possible for utility placement
within the dripline of a mature trees (trees measuring over 6 inches in DBH).
(lm) If roots are cut between March and August, trees may need supplemental deep
root watering at the discretion of the City ForesterManagerDirector. once per
week for at least 2 months after the roots are cut. When roots are cut between
September 1 and October 15, trees may need supplemental watering once per
week until at least October 31.
(mn) Trees impacted by construction activities roots shall not be fertilized for a period
of 1 year following the cessation of construction activities. Thereafter, for the
next 2 years, a light annual fertilization using a slow release nitrogen source is
acceptable.
(45) Tree Fencing
(a) Fencing material shall encircle any tree, including those on adjacent properties,
whose outer dripline edge is within 20 feet of any construction activities.
(b) Fencing material shall be a bright, contrasting color, durable, and at least 4 feet
high. Fence posts shall be comparable to metal Tposts or heavier posts and
placed at least 1.52 feet below ground.
(c) Fencing material shall be placed at the dripline or at least 15 feet from any tree
trunk, whichever distance is greater, and maintained in an upright position
throughout the duration of construction activities.
(d) The applicant for construction approval shall indicate fencing locations on the
landscaping tree protection plan.
(e) Heavy Oobjects, such as wood pallets or metal railings, shall not lean against or
come into contact with any tree trunk.
(56) Grade Changes: Grade changes, such as removing topsoil or adding fill material, shall
not occur within the dripline of any existing tree. If necessary as part of project or site
development and if approved by the City, retaining walls and tree wells may be used to
maintain the existing grade within the dripline of any tree may be acceptable when
constructed prior to site grading changes near the tree. A landscaping plan containing an
illustrated design scheme of the tree protection improvement shall be approved by the
City prior to initiating any grade changes near existing trees.
(67) Transplanting: Any proposed or required transplanting shall conform with the
requirements in Section 3.04(D), “Tree Relocation (Transplanting).”
(78) Chemical/Foreign Material Disposal
(a) Disposing of chemicals or foreign material anywhere on site or in the public
right- of- way is prohibited. This shall include, but is not limited to: paint, stain,
solvents, concrete or any construction material onsite, and rinse water from any
cans or tools containing chemicals.
(b) Soil samples may be taken to determine the presence of chemicals or foreign
materials for any planter containing proposed or existing plant material.
(89) Pruning: Pruning shall not occur during construction activities or the public
improvement warranty period, except to remove dead or damaged branches or to prevent
branch damage that could occur during construction, without the prior approval of the
City ForesterManagerDirector. Any approved pruning must be completed by a cCity of
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3-14 DESIGN AND CONSTRUCTION STANDARDS Effective: November 16, 2000TBD
Boulder licensed certified arborist. Pruning of healthy branches shall be delayed for a
period of 2 years after construction activities are completed.
(9) Watering: For trees 1”-3” diameter water weekly at a rate of 10 gallons/inch of
diameter; for trees 4”-9” diameter water 3x per month at a rate of 10 gallons /inch
of diameter; for trees 10” diameter or larger apply water 2x per month at the rate
of 15 gallons / inch of diameter. The above schedule should be followed April –
September; for Oct – March apply water once per month.
3.06 General Landscaping and Maintenance Requirements
(A) Protecting Existing Improvements
An applicant for construction approval shall preserve and protect all trees, plants, monuments, structures,
and public improvements from damage due to construction activities.
(1) Utilities: The applicant shall ask the appropriate utility company to stake exact locations
and depths of all water, sewer, electric, gas, or telephone lines prior to excavation, and
shall take the necessary precautions to protect underground lines from damage. If
damage occurs, the applicant shall pay all repair costs.
(2) Existing Trees: Protection shall comply with Section 3.05, “Tree Protection for
Construction Sites.”
(3) Responsibility for Damages: The applicant shall be responsible for any damage to
trees, plants, fences, buildings, roadways, sidewalks, and public and private property
resulting from the applicant’s activities. The City may require an applicant to provide, at
no cost to the City, devices durable fencing to prevent damage to fragile plant materials
or structures.
(4) Omissions and Discrepancies: Omissions from any approved landscaping plan or
specifications that affect the intent of the plans or specifications, or that are customarily
performed, shall be performed as if fully and clearly set forth and described in the plans
and specifications.
(B) Maintenance of Landscaping
(1) Landscaping Landscape maintenance shall begin immediately after each area is planted
and shall continue following City acceptance through the applicable warranty period , or
in perpetuity, as set forth in Section 93.34-9-12(d)(2), “Landscape and Screening
Maintenance and Replacement,” Section 949-12-13 “Subdivider Financial
Guarantees-19-2-14, “Required Improvements and Financial Guarantees,” or Section
95119-12-14, “Public Improvement Warranty,” B.R.C. 1981.
(2) Landscaping Landscape maintenance shall include, without limitation, watering,
weeding, cultivating, mulching, tightening and repairing of guys , removal of guy wires
and tree stakes after the first full growing season, removal of tree wrap prior to April 1,
removing dead branches, resetting plants to proper grade or upright position, replacing
dead plants and protecting the site from damage or vandalism. Landscape maintenance
also includes the removal of tree wrap and guy wires and tree stakes from all trees after
the first full growing season.
(3) If required by the City, the applicant for construction approval shall furnish written
maintenance instructions to the City for the care and maintenance of all newly planted
areas for the applicable warranty period. These instructions shall include, but are not
limited to: irrigation, staking, pruning, insect and disease control, and fertilizing.
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Table 3-6: Tree Characteristics
The following table describes the typical characteristics of trees on the Approved Street Tree List when
planted in non-paved landscape planting strips. Trees growing in tree grates or planting pits will have an
overall mature height of approximately 1/3 less than that of trees in non-paved areas.
Small Maturing Trees
(Under 25’ Mature Height)
COMMON & SCIENTIFIC NAME
SIZE AND FORM
CHARACTERISTICS
Crabapple (Malus ‘Red Barron’ or Malus
‘Centurion’
15-25' ht., 7-15' spread, broad
upright
Adaptable water requirements once established,
adapts well, attractive blossoms in early spring,
very little to no fruit, resistant to fireblight,
requires full sun
Goldenraintree (Koelreuteria paniculata)
20-25' ht., 15-20' spread, broadly
globe-shaped
Drought tolerant once established, tolerates wide
range of soil types, attractive yellow flowers in
mid-summer, yellow fall color, grows in full sun
or partial shade
Hawthorn (Crataegus spp. - thornless
cockspur or ‘Ohio Pioneer’)
15-25' ht., 15-25' spread, broadly
globe-shaped, plant tree form only
Adaptable water requirements once established,
tolerates salt and alkaline soils, attractive
blossoms in spring, thornless, resistant to
fireblight but susceptible to rust, requires full sun
Lilac, Japanese tree (Syringa reticulata)
15-25' ht., 15-20' spread,
moderately globe-shaped, plant tree
form only
Adaptable water requirements, attractive white
blossoms in late spring, golden fall color, grows in
full sun or partial shade
Maple, Amur (Acer ginnala)
15-20' ht., 15-20' spread, broadly
globe-shaped to irregular, plant tree
form only
Drought tolerant once established, can become
chlorotic in alkaline soils, brilliant red to orange
or yellow fall color, requires full sun
Maple, Norway (Acer platanoides ‘Crimson
Sentry’)
25' ht., 15' spread, dense and
columnar
Adaptable water requirements once established,
dark purple foliage in spring and summer,
susceptible to sunscald, requires full sun
Maple, Tatarian (Acer tataricum)
20-25' ht., 15-20' spread,
moderately globe-shaped, plant tree
form only
Adaptable water requirements once established,
seeds are a rosy red color, yellow to orange red
fall color, grows in full sun or partial shade
Oak, Gambel (Quercus gambelii)
10-25' ht., 10-15' spread, broadly
globe-shaped, plant tree form only
Tolerant of dry and alkaline soils, Colorado
native, yellow to red fall color, requires full sun
Pear (Pyrus calleryana ‘Chanticleer’)
20-30' ht., 15-20' spread, narrow
pyramidal shape
Adaptable water requirements once established,
tolerates salt and alkaline soils, attractive white
blossoms in spring, maroon fall color, resistant to
fireblight, requires full sun
Prunus (Prunus spp.) Ex. Cherries, plums,
almonds, apricot
20-25' ht., 20-30' spread,
moderately globe-shaped, plant tree
form only
Adaptable water requirements, most have
attractive spring blossoms, bears fruit, grows in
full sun or partial shade
Redbud (Cercis canadensis)
20-25' ht., 20-30' spread,
moderately globe-shaped, plant tree
form only
Moist to adaptable water requirements, needs
protected location, pink to lavender blossoms in
early spring, yellow fall color, prefers filtered
shade to shade
Serviceberry (Amelanchier spp.)
25' ht., 10-20' spread, moderately
ovate-shaped, plant tree form only
Adaptable water requirements once established,
prefers acidic soils, attractive flowers in early
spring, yellow to orange red fall color, plant
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varieties resistant to fireblight, grows in sun or
shade
Medium Maturing Trees
(30-45’ Mature Height)
COMMON & SCIENTIFIC NAME
SIZE AND FORM
CHARACTERISTICS
Cherry, Sargent (Prunus sargentii)
30-45' ht., 20-30' spread,
moderately globe-shaped
Adaptable water requirements, attractive
blossoms in spring, bears fruit, grows in full
sun or partial shade
Crabapple (Malus ‘Indian Magic’, ‘Indian Summer’,
‘Radiant’, ‘Spring Snow’)
15-30' ht., 15-30' spread, broad
globe-shaped to rounded
Adaptable water requirements once
established, adapts well, attractive blossoms in
early spring, very little to no fruit, resistant to
fireblight, requires full sun
Hackberry (Celtis occidentalis ‘Prairie Pride’)
45' ht., 30-40' spread, moderately
pyramidal-shaped
Drought tolerant once established, tolerates a
wide range of soil conditions, yellow fall color,
does not develop witches broom, grows in full
sun to partial shade
Hawthorn (Crataegus spp. - thornless cockspur or
‘Ohio Pioneer’)
15-25' ht., 15-20' spread, broadly
globe-shaped
Adaptable water requirements once
established, tolerates salt and alkaline soils,
attractive blossoms in spring, thornless,
resistant to fireblight but susceptible to rust,
requires full sun
Honeylocust (Gleditsia triacanthos var. inermis
‘Imperial’ or ‘Sunburst’)
30-45' ht., 30-35' spread,
moderately globe-shaped
Drought tolerant once established, tolerant of
salt and alkaline soils, transplants easily,
fruitless, thornless, yellow fall color,
susceptible to many insect and disease
problems, requires full sun
Hop Hornbeam (Ostrya virginiana)
30-45' ht., 20-35' spread,
moderately ovate-shaped
Requires moist to moderately dry soils once
established, prefers acidic soils, salt sensitive,
grows in full sun or partial shade
Hornbeam, European (Carpinus betulus)
30-45' ht., 15-30' spread, dense,
narrow pyramidal to oval-shaped
Adaptable water requirements once
established, grows well in clay and alkaline
soils, salt sensitive, yellow fall color, grows in
full sun or partial shade
Linden, Littleleaf (Tilia cordata ‘Greenspire’ or
‘Glenleven’)
40-45' ht., 25-35' spread, broadly to
moderately pyramidal-shaped
Tolerates alkaline soil, withstands compaction,
salt sensitive, yellow fall color, young trees
susceptible to sunscald, grows in full sun or
partial shade
Maple, Norway (Acer platanoides ‘Cavalier’ or
‘Drummondi’)
35-45' ht., 30-40' spread, broadly
globe-shaped
Adaptable water requirements, deep maroon
leaf color, susceptible to sunscald, requires full
sun
Maple, Hedge (Acer campestre)
25-45' ht., 25-35' spread, dense,
moderately globe-shaped
Adaptable water requirements once
established, tolerates compaction and alkaline
soils, easily transplanted, yellow fall color,
grows in full sun or partial shade
Maple, Wasatch (Acer grandidentatum)
20-30' ht., 20-25' spread, broadly
globe-shaped
Drought tolerant once established, tolerant of
alkaline soils, very slow to establish, Colorado
native, yellow to red orange fall color, grows in
full sun or partial shade
Ohio Buckeye (Aesculus glabra)
30-45' ht., 25-35' spread, broadly
ovate to globe-shaped
Drought tolerant once established, large fruit,
purple to red fall color, requires full sun
Pear (Pyrus spp. - Ussurian or Callery - avoid
‘Bradford’ variety)
30-40' ht., 25-35' spread,
moderately columnar-shaped
Adaptable water requirements once
established, tolerates salt and alkaline soils,
attractive white blossoms in spring, maroon fall
color, resistant to fireblight, requires full sun
45' ht., 25-30' spread, moderately
Adaptable water requirements once
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Turkish Filbert (Corylus colurna) pyramidal-shaped established, tolerates alkaline soil, difficult to
transplant, free from insect and disease
problems, requires full sun
Large Maturing Trees
(Over 45’ Mature Height)
COMMON & SCIENTIFIC NAME
SIZE AND FORM
CHARACTERISTICS
Ash, Green (Fraxinus pennsylvanica
‘Patmore’ or ‘Marshall’s Seedless’ or
‘Newport’)
50-60' ht., 35-45' spread,
moderately to broadly ovate-
shaped
Drought tolerant once established, tolerates
salt and alkaline soils, transplants easily,
yellow fall color, susceptible to both
brownheaded ash sawfly and lilac/ash borer,
requires full sun
Ash, White (Fraxinus americana
‘Autumn Applause’ or ‘Autumn
Purple’ or ‘Rosehill’)
40-60' ht., 40-50' spread,
moderately globe-shaped
Adaptable water requirements, purple to red
fall color, susceptible to both brownheaded
ash sawfly and lilac/ash borer, requires full
sun
Baldcypress (Taxodium distichum)
50-60' ht., 20-40' spread,
moderately pyramidal-shaped
Tolerates wet soils and moderate drought
once established, deciduous conifer, golden
yellow fall color, free from insect and
disease problems, requires full sun
Catalpa, Western (Catalpa
speciosa)
40-60' ht., 30-50' spread,
moderately ovate-shaped
Drought tolerant once established, large
attractive white blossoms in summer,
produces pod fruit, requires full sun
Coffeetree, Kentucky
(Gymnocladus dioicus)
50-70' ht., 40-50' spread,
moderately globe-shaped
Drought tolerant once established, tolerant
of alkaline soils, free from insect and disease
problems, requires full sun
Elm, American (Ulmus americana
‘Brandon’ or ‘Valley Forge’)
45-55' ht., 40-50' spread, broadly
vase-shaped
Adaptable water requirements once
established, tolerant of salt and alkaline
soils, fast growth rate, easily transplanted,
yellow fall color, requires full sun
Hackberry, Common (Celtis
occidentalis)
50-60' ht., 40-50' spread,
moderately globe-shaped
Drought tolerant once established, tolerant
of salt and a wide range of soil conditions,
requires full sun
Honeylocust (Gleditsia triacanthos
var. inermis ‘Shademaster’ or
‘Majestic’)
50-60' ht., 30-40' spread,
moderately globe-shaped
Drought tolerant once established, tolerant
of salt and alkaline soils, transplants easily,
fruitless, thornless, yellow fall color,
susceptible to many insect and disease
problems, requires full sun
Horsechestnut, Common (Aesculus
hippocastanum)
50-60' ht., 50-60' spread, broadly
globe-shaped
Adaptable water requirements, has attractive
large white blossoms in early summer, large
fruit, requires full sun
Linden, American (Tilia americana
‘Legend’ or ‘Redmond’)
50-60' ht., 30-40' spread,
moderately pyramidal-shaped
Adaptable water requirements once
established, tolerant of alkaline soils, easily
transplanted, young trees susceptible to
sunscald, grows in full sun or partial shade
Linden, Littleleaf (Tilia cordata
‘Greenspire’ or ‘Chancellor’)
45-60' ht., 40-50' spread, broadly
pyramidal-shaped
Adaptable water requirements, tolerant of
alkaline soils and pollution, easily
transplanted, yellow fall color, young trees
susceptible to sunscald, requires full sun
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Maple, Norway (Acer platanoides
‘Deborah’ or ‘Emerald Queen’)
45-60' ht., 40-50' spread, broadly
globe-shaped
Adaptable water requirements, deep maroon
leaf color for ‘Deborah’, yellow fall color
for ‘Emerald Queen’, susceptible to
sunscald, requires full sun
Maple, Red (Acer rubrum
‘Northwood’ or ‘Red Sunset’)
45-55' ht., 25-40' spread,
moderately globe-shaped to
upright
Adaptable water requirements once
established, can become chlorotic in alkaline
soils, salt sensitive, orange red to brilliant
red fall color, requires full sun
Maple, Sugar (Acer saccharum
‘Green Mountain’ or ‘Legacy’)
50-60' ht., 30-40' spread,
moderately ovate-shaped
Adaptable water requirements once
established, prefers acidic soils, salt
sensitive, red to orange fall color, can grow
in full sun or shade
Oak, Bur (Quercus macrocarpa)
50-80' ht., 50-80' spread, broadly
ovate to broadly globe-shaped
Drought and wind tolerant once established,
tolerant of a wide range of soil types, yellow
to brown fall color, requires full sun
Oak, English (Quercus robur)
50-80' ht., 50-80' spread, broadly
ovate to broadly globe-shaped
Tolerant of a wide range of soil types,
yellow to yellow-brown fall color, requires
full sun
Oak, Shumard (Quercus shumardii)
50-80' ht., 50-80' spread, broadly
ovate to broadly globe-shaped
Adaptable water requirements once
established, tolerates compaction and salt,
does better in alkaline soils than red oak,
russet red to red fall color, requires full sun
Oak, Red (Quercus rubra)
50-80' ht., 50-80' spread, broadly
ovate to broadly globe-shaped
Prefers acidic soils, can become chlorotic in
alkaline soils, russet red to bright red fall
color, requires full sun
Oak, Swamp White (Quercus
bicolor)
50-80' ht., 50-80' spread, broadly
ovate to broadly globe-shaped
Drought tolerant once established but can
also withstand wet conditions, can become
chlorotic in alkaline soils, yellow fall color,
requires full sun
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10-i
CITY OF BOULDER
DESIGN AND CONSTRUCTION STANDARDS
CHAPTER 10
STREETSCAPING STREETSCAPE & LANDSCAPE
STANDARDS
TABLE OF CONTENTS
Section Page
10.01 GENERAL ...................................................................................................................................................... 1 S
(A) INTENT 1
(B) SCOPE 1
(C) REFERENCE STANDARDS .................................................................................................................................. 1
(D) CITY APPROVAL REQUIRED ............................................................................................................................. 1
(E) WATER CONSERVATION ................................................................................................................................... 1
(F) PUBLIC LANDS OTHER THAN PUBLIC RIGHTS-OF-WAY ................................................................................... 1
10.02 SITE PREPARATION ...................................................................................................................................... 1
(A) DESCRIPTION ................................................................................................................................................... 1
(B) MATERIALS .................................................................................................................................................... 21
(C) CONSTRUCTION REQUIREMENTS .................................................................................................................... 32
10.03 PLANTING ........................................................................................................................................................ 5
(A) DESCRIPTION ................................................................................................................................................... 5
(B) MATERIALS .................................................................................................................................................... 65
(C) CONSTRUCTION REQUIREMENTS .................................................................................................................... 98
10.04 SEEDING/SODDING ................................................................................................................................. 1311
(A) DESCRIPTION ............................................................................................................................................. 1311
(B) MATERIALS ................................................................................................................................................ 1312
(C) CONSTRUCTION REQUIREMENTS ................................................................................................................ 1816
10.05 UNDERGROUND IRRIGATION SYSTEM ........................................................................................... 2119
(A) DESCRIPTION ............................................................................................................................................. 2119
(B) MATERIALS ................................................................................................................................................ 2219
(C) CONSTRUCTION REQUIREMENTS ................................................................................................................ 2624
LIST OF TABLES
Number Page
Table 10-1: Topsoil Mechanical Analysis ................................................................................................................10-2
Table 10-2: Minimum Root Ball Sizes .....................................................................................................................10-7
Table 10-3: Wildflowers ......................................................................................................................................... 10-14
Table 10-4: Grasses ................................................................................................................................................ 10-15
Table 10-5: Soil Amendment Mix Mechanical Analysis ........................................................................................ 10-15
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10.01 General
(A) Intent
The Streetscaping lLandscape Standards are intended to compliment complement the design
standards specified in Chapter 3, “Streetscape Design and Tree Protection,” of these Standards,
and provide minimum standards for the construction and planting of streetscapes in public rights-
of- way.
(B) Scope
These Standards apply to streetscapes public landscape located, standing, or growing within or
upon any City of Boulder public right- of- way or park, and as specifically referenced in other
City of Boulder codes. The streetscape requirements of this chapter are in addition to those set
forth in Chapter 3, “Streetscape Design and Tree Protection,” and applicable streetscape drawings
in Chapter 11, “Technical Drawings,” of these Standards and the B.R.C. 1981 .
(C) Reference Standards
Where not specified in these Standards or the B.R.C. 1981, in order to protect the public health,
safety, and welfare, the Director of Public Works in consultation with the Director of Parks and
Recreation will specify the standards to be applied to the design and construction of public
landscapes streetscapes and the planting of trees, and may refer to one or more of the references
listed in the References Section of these Standards.
(D) City Approval Required
All work associated with the planting, maintenance, and removal of trees and landscaping
materials located, standing, or growing within or upon any City of Boulder public right - of- way
is subject to City of Boulder approval or permit issuance as set forth in Chapter 8-5, “Work in the
Public Right- of- Way and Public Easements,” and Chapter 6--6, “Protection of Trees and
Plants,” B.R.C. 1981.
(E) Water Conservation
All landscaping shall be designed for maximum water efficiency, as specified in Section 93.33,
“Landscape Design Standards,”9-9-12 “Landscaping and Screening Standards” B.R.C. 1981.
(F) Public Lands Other Than Public Rights-of-Way
Unless otherwise approved noted in city standardsby the Director in consultation with the
Director of Parks and Recreation, all lLandscaping construction activities on public lands other
thanincluding public rights- of- way, such as parks, open space and greenway corridors, are
included in exempt from the construction and planting requirements of these Standards.
However, these Standards may be used as a basis for construction and planting activities on all
public lands.
10.02 Site Preparation
(A) Description
Site preparation includes, without limitation, layout, tree protection, demolition, clearing,
excavation, fill and backfill, addition of topsoiling, and finish-grading.
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(B) Materials
Planting soil nutrient and mechanical compositions are unique to individual sites, species, and
project conditions such as geotechnical recommendations and green infrastructure requirements.
One soil type may not be viable across an entire project. The below specifications are guidelines,
however, all planting conditions must be analyzed to ensure proper soil nutrients and mechanical
composition are provided.
(1) (1) General Definition of Imported Fill: Imported fill for landscaping shall be
clean, fertile, sandy loam soil that is free from turf, lime, ashes, debris, noxious
weeds, roots, stones over 4 inches in diameter, harmful chemicals, or other
materials that are detrimental to plant growth. Fill shall have a pH of 6.0 to 8.0,
salt of less than 2 mmhos/cm, sodium absorption ratio of less than eight, and at
least an 85 percent germination rate for narrow and broadleaf plants. Fill shall not
be hauled in a frozen, wet, or muddy condition. An agricultural suitability analysis of
the proposed topsoil from an accepted, accredited Testing Agency at Contractor’s cost is
required to confirm nutrient and mechanical requirements are met.
(2) (2) General Definition of Native TopSsoil: Surface soil in the areas designated on
the soils plan as existing soil, that is not altered, compacted to root limiting density,
graded or contaminated before or during the construction process and considered
acceptable for planting and long term health of the plants specified either as it exists or
with only minor modification. An agricultural suitability analysis of the proposed topsoil
from an accepted, accredited Testing Agency at Contractor’s cost is required to confirm
nutrient and mechanical requirements are met.
Soil Requirements for Imported and Native Soil:
(1)(3)
(a) Topsoil shall be fertile, friable, sandy loam topsoil. Topsoil shall be of
any admixture of subsoil or slag and shall be free of stones over 1 ½
inches in diameter, lumps, refuse, plants or their roots, sticks, noxious
weeds, salts, soil sterilants or other material that is detrimental to plant
growth. If topsoil is delivered, it shall be obtained from a well-drained
site that is free of flooding. Topsoil shall not be delivered or used while
in a frozen or muddy condition.
(b) Topsoil shall have an acidity range of pH 6.0 to 7.58.0 and contain not
less than 5 percent organic matter as determined by loss on ignition of
moisture-free samples dried at 100 degrees Centigrade. Topsoil shall
have salt of less than 2 mmhos/cm and a sodium absorption ratio of less
than eight.
(c) Topsoil shall meet the mechanical analysis outlined in Table 10-1,
“Topsoil Mechanical Analysis,” of these Standards:
Table 10-1: Topsoil Mechanical Analysis
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Passing percent
Retained percent
1-inch screen
100%
0 - 0%
½-inch screen
97 - 100%
0 - 3%
No. 100 mesh sieve
60 - 40%
40 - 60%
(d) Topsoil shall have at least an 85 percent germination rate for narrow and
broadleaf plants.
(C) Construction Requirements
(1) Layout
(a) The contractor is responsible for:
(i) Establishing and recording all necessary boundary points, lines,
elevations, grades, access points, and benchmarks onsite for proper
control, landscape protection, coordination with subcontractors, and
execution of the work.
(ii) Verifying all furnished survey and topographic data, all points, lines, and
elevations.
(iii) Notifying the Director of any discrepancies between information on
approved construction plans and actual site or field conditions or
measurements and receive approval for required modification prior to
continuing work.
(iv) Staking all cuts and fills on the sites as shown on the grading plan.
(b) Shoulders and toes of slopes shall be smoothly blended to the flat areas.
(c) No cut or fill is allowed within the dripline of existing trees without the prior
approval of the City ManagerDirector per section 3.05B(5) of these standards.
(2) Clearing of Project Site: The contractor is responsible for:
(a) Removing from the site all trees and shrubs, brush and weed growth, stumps, and
root systems designated on the approved construction plans for removal.
(i) All trees to be removed shall be marked with an “X” in blue permanent
marking and approved by the City ManagerDirector prior to removal.
(ii) All other plant material not designated for removal shall be protected and
maintained consistent with the standards of Chapter 3.05 B.
(iii) Stripped-off brush and weed growth shall be hauled offsite. No burning
or nesting of materials shall be permitted onsite.
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(b) Maintaining adequate fire protection while clearing operations are underway.
(c) Replacing any existing sod damaged by construction operations. Replacement
sod shall meet the standards of Section 10.04, “Seeding/Sodding,” of these
Standards.
(d) If specifically required on the approved construction plans, scalping the top of
soil, including grasses and roots, to a depth specified in the plans and stockpile
onsite or remove as indicated.
(3) Excavation: The contractor is responsible for:
(a) Stripping, stockpiling, and replacing existing topsoil in areas of fill on the
finished grade to at least 4 inches deep.
(b) Excavating so as to provide adequate drainage of the site at all times.
(c) Using hand methods of excavation within the dripline of trees and per Root
Protection in Chapter 3.05 (B) (3).
(4) Fill and Backfill Operations: The contractor is responsible for the following:
(a) Obtaining the Director’s approval of the subgrade before commencing soil
preparation, topsoilingadding of topsoil, finish grading or planting, and obtaining
the Director’s approval of the finish grade before commencing planting,
mulching or other subsequent operations. The following grading tolerances shall
be applied:
(i) Tolerances shall not exceed 0.1 feet above or below desired subgrade
elevations in planted areas, and no tolerance will be allowed on
subgrades prepared for paving or site improvements, or subgrades
immediately adjacent to curbs or island pavements.
(ii) Settling of finish grade shall not exceed 0.1 feet.
(b) Completing clearing operations before beginning any filling or backfilling.
(c) If sufficient suitable fill or backfill material is not available on the project site,
furnishing additional materials according to standards for hauled-in fill or topsoil,
as required in these Standards.
(d) Placing fill and backfill in layers not to exceed 6 inches in compacted depth with
the following compaction standards:
(i) Each layer shall be compacted to the specified density. Landscaping fill
and backfill shall be compacted to no less than 80 percent and no more
than 85 percent density in areas to be planted.
(ii) Compaction shall not occur when soil is wet.
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(e) Ensuring that filling and backfilling shall provide adequate site drainage at all
times. Fill or backfill shall not be placed on wet ground.
(5) Finish Grading
(a) Work in this section shall consist of cutting, filling, shaping, and grading
according to the lines, grades, elevations and cross sections on the approved
landscaping or engineering plans.
(b) The contractor is responsible for the following:
(i) Completing all finish grading onsite. The top of the subgrade shall be the
depth below the finished grade as required for pavements, sod, walks,
mulches and other site improvements.
(ii) Protecting the finish grade areas and regrading to correct any
irregularities caused by hauling materials or by other operations over the
finished grade.
(iii) Repairing any erosion or other damage resulting from weathering action
before final acceptance.
(c) Excavated and filled sections and adjacent transition areas shall be smooth,
properly compacted and free from irregular surface changes. The degree of
finish grading shall be that ordinarily obtained from either blade, grader, or
scraper operations. Where finishing cannot be satisfactorily completed with
power equipment, hand methods shall be used.
(d) Unless otherwise indicated, the subgrade shall be evenly sloped to provide
drainage away from site improvements or the centerline of medians. Swales
shall be cut as shown on the plans, but shall not reduce the thickness of the
topsoil specified.
(e) Finish grading shall conform to the grade elevations shown on an approved
landscaping plan and shall be free from debris and other materials that would be
detrimental to the subgrade. Settling of any finish grade shall not be more than
0.1 feet, and if settling is greater, the contractor shall bring the grade to specified
elevations.
10.03 Planting
(A) Description
Planting includes, without limitation, the placement of live trees and shrubs, the placement of
materials to protect and enhance plant growth, and the methods applied in planting and
maintaining landscape plants.
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(B) Materials
(1) Edger: Ryerson or approved equivalent steel edger, 1/8-inch by 4- inch steel with steel
stakes, painted with rust-inhibiting black paint. The edger shall have a rolled or folded
edge or be capped with plastic safety-edged material.
(2) Filter Fabric: Fabric shall not be used with any planting unless specifically approved as
part of a detailed landscape plan. Fabric shall not be used within the driplines of any
existing or within 10 feet of any newly planted trees. If approved, fabric shall be 30.1-mil
DeWitt Weed Barrier or approved equivalent.
(3) Pesticides: Comply with the specifications of Section 6-10, “Pesticide Use,” B.R.C.
1981. Pesticide use shall be consistent with the city’s adopted integrated pest
management (IPM) policy.
(4) Tree Wrapping Material: New, 4-inch wide, bituminous impregnated tape, corrugated
or crepe paper, brown in color, specifically manufactured for tree wrapping. Tree
wrapping shall be fixed with pliable or nonbinding tape. No wire shall be used. If used,
tree wrap shall be removed by April 1 of the following growing season.
(5) Compost: Well-weathered and weed-free cow or sheep manure or other composted
materials. No mountain peat shall be used.
(6) Stakes: Green 8-foot steel tee posts with blade.
(a) Trees shall be secured to stakes using minimum 2 inch wide nylon and cotton
blend webbing with heat sealed ends, a tensile strength of 1000 pounds and brass
grommets for attachment of wire between strap and stake.
(b) Grommets shall be 1 ¼ - inch in diameter with a ½ -inch diameter eye that is set
at least ½ -inch from end of strap.
(c) Wire shall be 12-gauge galvanized steel covered with a PVC sleeve.
(d) Straps shall be of sufficient length in relation to tree caliper so that grommets do
not touch trunk.
(e) A protective cap shall be secured to the top of all stakes.
(7) Mulch:
(a) Wood chip mulch shall be clean wood chips or fiber free of soil or man-made
debris shredded into coarse pieces ranging in size from 1 inches to 3 inches. All
median landscape plantings shall be mulched with 24 to 643 to 4 inches of wood
chips. 2 to 4 inches of “Squeegee” (1/4-inch minus washed sand) may be
substituted for wood mulch for street median applications only.
(b)(a)
(b) Rock, gravel or cobblestone or other inorganic material shall not be used in
planting beds mulch shall not be used in planting beds, except as a temporary or
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permanent mulch. until full plant coverage is achieved, or as permanent mulch
under shrubs. Rocks used in the public right-of-way or adjacent to sidewalks
must be 1 ½ to 3 inches in diameter. Gravel or cobblestone shall not be used as
mulchunless specifically approved as part of a detailed landscape plan.
(c) For medians and bikeways, landscape fabric shall not be used as a weed barrier.
(8) Plant Materials:
(a) All plants shall be “Colorado Grown,” “Colorado Fielded,” or “Northern Grown”
as described below, unless otherwise specified in these Standards, except for
plants of the genus Juniperus.
(i) Colorado Grown: plants grown in Colorado nursery fields for the major
portion of their lives.
(ii) Colorado Fielded: plants shipped in or collected that have grown in
Colorado nursery fields for at least two full growing seasons prior to
delivery.
(iii) Northern Grown: plants grown in nurseries for at least two full growing
seasons located in hardiness Zones 1 through 5, as shown on a United
States Department of Agriculture map.
(b) All plants shall be appropriate for the local climate and site specific growing
conditions. All plants shall be of species identified under and allowed by these
Standards or other city adopted references and shall conform to the following:
(i) Selected to meet the goal of maximum water efficiency and zoned or
grouped according to their water requirements in accordance with
Section 9-9-12 .”Landscaping and Screening Standards” B.R.C. 1981.
(ii) Individually identified on legible, weatherproof labels securely attached
to the plants. Labels shall be durable and shall remain legible for at least
60 days from site delivery.
(iii) Labels shall include the correct genus, species, variety name, and
accepted common name of the plant, as well as the size or grade of stock,
and source nursery of the plant.
(iv) Labels shall remain until after City inspection and then shall be removed
by the contractor.
(c) Tree selection and placement shall be in accordance with Section 3.03, “Tree
Selection and Placement,” of the these Standards.
(d) Trees shall conform to and have the following characteristics:
(i) A well-developed branch structure typical of the size and species with no
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“V” crotches, codominate stems, or included bark. The height of
branching should bear a relationship typical of size and species so that
the crown of the tree will be in balance as the tree grows.
(ii) Healthy buds, stems, and bark that are without mechanical injury or ,
insect, or disease injury signs or symptoms until final acceptance.
(iii) Healthy, vigorous, and free from visual defects, mechanical injuries,
plant diseases, and all forms of insect infestation until final acceptance.
(iv) A well-branched and vigorous root system typical of size and species
and free from bent or kinked roots, roots girdling the trunk, and other
defects.
(v) All trees shall be balled and burlapped. Root balls shall have a sufficient
diameter for the fiberous and feeding root system necessary to provide
for full recovery of the tree following planting. Minimum root ball sizes
shall meet the following specifications outlined in Table 10-2,
Table 10-2: Minimum Root Ball Sizes
Caliper Minimum Root Ball Diameter
1 ½” 20”
1 ¾” 22”
2” 24”
2 ½” 28”
3” 32”
(v)(vi) Shrubs may be either balled and burlapped or container grown.…
Table 10-2: Minimum Root Ball Sizes
Caliper Minimum Root Ball Diameter
1 ½” 20”
1 ¾” 22”
2” 24”
2 ½” 28”
3” 32”
(e) All trees and shrubs shall be freshly dug at time of delivery, unless they are
container-grown. Plants other than bare root stock that have been heeled-in for
more than 1 month or that exhibit roots outside the original ball shall not be
accepted. Bare root stock placed in cold storage for more than 2 months or that
exhibits new top growth will not be accepted.
(f) Moss rock shall be sandstone boulders with 75 percent or more exposed
surface covered with lichens. Boulders shall have rounded natural edges and a
character and shape consistent with native landscape rock settings. No split,
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bruised face, slab-type, layered, or slide rocks shall be used without prior
approval and acceptance by the Right of Way inspector.
(C) Construction Requirements
(1) Layout and Identification: The contractor shall use stakes, flags, or containerized
plants to locate all trees and shrubs according to an approved landscape plan.
(2) Schedule
(a) Nothing shall be planted between October 15 and March 1 without prior written
approval of the City ManagerDirector. Stock, other than container-grown stock,
shall not be planted between June 1 and September 1 without prior written
approval of the City ManagerDirector. Bare root stock shall not be planted after
April 30 or if plants have begun to leaf out.
(b) Nothing shall be planted during freezing or excessively windy, hot, or wet
weather or when the ground conditions cannot be properly worked for digging,
mixing, raking, or grading.
(c) Nothing shall be planted until the adjacent site improvements, pavements,
irrigation installation and finish grading is completed. The contractor shall test
the irrigation system in the presence of the Director. The irrigation system shall
be in approved, operating condition prior to any planting.
(3) Plant Protection and Delivery
(a) The contractor shall protect all installed plant material from injury, excessive
drying or winds, improper ventilation, over watering, freezing, high
temperatures, or any other condition damaging to the plant until final acceptance.
Any plants showing evidence of poor care or that are molded, mildewed, wilted,
or dried-out shall be rejected. Colored waxes or other materials that coat the
aerial parts of plants, or the removal of primary buds and/or shoots, including
terminal buds and first order leaders, of plants are not acceptable.
(b) (b) Plant materials shall be planted on the day of delivery if possible. All
plants not planted on day of delivery shall be placed in a temporary nursery, kept
moist, shaded and protected from sun and wind. If balled and burlapped plants
are not planted on the day of delivery, they shall be heeled-in immediately in the
temporary nursery, kept moist and protected with damp soil, mulchmoss, or other
acceptable material. All plants shall be planted within 48 hours after delivery.
Plants shall not be bound with wire or rope that may damage the bark or break
branches. Plants shall be lifted and handled from bottom of ball or container, and
shall not be dropped or lifted by the trunk, stem or foliage. Plants with balls that
are loose, cracked, broken, man-made or completely dry or plants with trunks
loose in the ball before or during planting operations shall not be accepted and
shall be removed from the site at contractor's expense.
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(c) The root collar is not to be deeper than 4 inches below shall be flush with the top
of the soilroot ball.
(c) The contractor shall deliver all packaged landscape materials to the site in
original unopened containers bearing name, trade name, manufacturer,
trademark, and conformance to State Law.
(d) Existing trees shall be protected per Section 3.05, “Tree Protection for
Construction Sites,” of these Standards.
(4) Excavation of Planting Pit
(a) All plant pits shall be centered on the plant location and excavated in a
cylindrical shape with vertical sides and flat bottom. The depth of the plant pit
shall be measured from the adjacent finished grade of the soil, not from the
mulch. The base of all soil balls shall be placed on undisturbed soil.
(b) Trees: The diameter of all tree pits shall be at least two times the diameter of the
ball or spread of the roots. Tree pits shall be excavated so that the top of the ball
will shall be 3 2 inches above finished grade grade when irrigated and 2 inches
when not irrigated.
(c) Shrubs: The diameter of all shrub pits shall be at least two times diameter of the
ball or spread of roots. Shrub pits shall be excavated so that the top of the ball
will be 1 inch above finish grade.
(d) Vines and Ground Covers: The diameter of all vine and ground cover pits shall
be two times the spread of roots. The planting pit shall be excavated so that the
top of the ball is 1 inch above finish grade.
(e) All holes and pits shall be protected as specified in the General Conditions at all
times when work is not being carried on at the site of excavation.
(5) Planting and Staking for Plant Installation
(a) Plants shall be set in the center of the pit on the undisturbed subgrade.
Immediately after setting in the pit, all materials shall be completely removed
from the ball and trunk, including but not limited to plastic, metal, wire, wood,
cardboard, paper, fiber, burlap, and twine. Container removal and plant handling
shall minimize injury to the plant, the root system, and the soil ball. If the root
system of a container grown plant has become container-bound, the outside of
the root masss shall be cut with a hand saw on all four sides gently vertically
cut on two sides of the root ball prior to planting.
(b) All plants shall be placed and kept plumb and straight as the pit is filled with
backfill. Any plant that is not plumb prior to final acceptance shall be rejected.
(c) After placing plant in the pit, the hole around the plant root system shall be
halfway backfilled and any large air pockets removed by hand with the blunt,
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handle end of a shovel or other such hand tool. If the ball is excessively dry, the
contractor shall then insert a deep watering device into the ball at a 45 degree
angle every 12 inches for 1 minute. The pit shall then be lightly filled with
backfill mix and compacted again with the shovel. No mechanical compaction
shall be allowed.
(d) The pit shall then be watered by thoroughly saturating the backfill with water to a
minimum depth of 3 feet. No watering shall be done prior to this time. Watering
shall be repeated once when all free water has disappeared; this second watering
shall not be completed if the subgrade around the pit is already moist. After
watering, the contractor shall add the necessary soil to establish the finish grade
level before adding specified mulch. The contractor shall remove all surplus soil
and debris, and stake and guy trees immediately after planting.
(e) For all trees, the contractor shall drive stakes 3 feet vertically into firm soil
outside the planting pit with blade on tree side. The contractor shall run a double
strand of wire through one grommet in the strap, wrap the strap around trunk at
no more than one-third the height of tree, and run wire through other grommet
and back to stake. Strap and wire attachment between the stake and tree shall be
adjusted so that straps are under just enough tension to avoid visible sag in lines.
Rigid guying shall not be accepted. Straps and wires shall be placed so as to be
perpendicular to the trunk. Stakes shall be parallel or slightly angled away from
the trunk.
(f) The contractor shall place stakes according to tree height or caliper as follows:
deciduous trees under 2 inches - one stake oriented northwest; deciduous trees 2”
and larger, but less than 3 inches and evergreen trees less than 5 feet in height -
two stakes oriented northwest and southeast; deciduous trees 3 inches and larger
and evergreen trees 5 feet and larger - three stakes with one oriented northwest
and the other two oriented 120 degrees in either direction form northwest. All
deciduous trees shall have a sod-free base at least 3 feet in diameter. All
evergreen trees shall have a sod free base extending to the dripline. This sod free
area shall be extended where necessary to include all stakes. The contractor shall
return to the site and remove stakes between May 21 and June 7 after7 after one
full growing season
(d)(g) (d) Unless otherwise specified, all areas designated for mass planting
such as for ground covers or vines shall be amended with 56 cubic yards
per 1,000 square feet of manure compost. The contractor shall first
prepare the subgrade by discing or rototilling the subgrade to a depth of 8
inches. No ripping or chiseling shall be allowed. After preparing the
subgrade, the amendments shall be thoroughly rototilled into the soil to a
depth of 8 inches. The contractor shall remove any rocks, debris or
foreign matter in excess of 1 inch in length or diameter encountered to an
8-inch depth or adequate to accommodate typical root depth of the
specified plant material.
(e) (ef) For all trees, the contractor shall drive stakes 3 feet vertically into
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firm soil outside the planting pit with blade on tree side. The contractor
shall run a double strand of wire through one grommet in the strap, wrap
the strap around trunk at no more than one-third the height of tree, and run
wire through other grommet and back to stake. Strap and wire attachment
between the stake and tree shall be adjusted so that straps are under just
enough tension to avoid visible sag in lines. Rigid guying shall not be
accepted. Straps and wires shall be placed so as to be perpendicular to the
trunk. Stakes shall be parallel or slightly angled away from the trunk.
(f)
(g) The contractor shall place stakes according to tree height or caliper as
follows: deciduous trees under 2 inches and under - one stake oriented
northwest; deciduous trees 2” and larger, than 2 inches but less than 3
inches and evergreen trees less than 5 feet in height - two stakes oriented
northwest and southeast; deciduous trees 3 inches and larger and
evergreen trees 5 feet and larger - three stakes with one oriented northwest
and the other two oriented 120 degrees in either direction form northwest.
All deciduous trees shall have a sod-free base at least 3 feet in diameter.
All evergreen trees shall have a sod free base extending to the dripline.
This sod free area shall be extended where necessary to include all stakes.
The contractor shall return to the site and remove stakes between May 21
and June 7 the following spring after one full growing season.
(h) The contractor shall remove all stakes and guy wires no more than one
year from the date of tree installation.
(6) Spraying, Wrapping, Pruning, Watering and Mulching for Plant Installation
(a) All deciduous trees shall be wrapped by the contractor from November 1 - 15 of
the year in which they are planted. Specified tree wrap shall be cut in a
continuous strip of sufficient length to wrap the tree. This wrapping shall begin
at the ground line with overlapping wraps of 1½ inches terminating above the
lowest main branch of the tree. Final wrap shall be secured with tape in at least
three places. The contractor shall return to the site and remove wrap from April
1 - 15 of the following spring. The contractor shall notify the City at least 1
week prior to wrap removal.
(b) After inspection, and with the approval of the City, the contractor shall prune
plants as necessary to remove only dead, injured, diseased, or crossing branches.
All cuts shall be made just outside of the flare (branch collar) of the branch base.
All pruning shall be executed so as to preserve the natural form and character of
the plant. The contractor shall return to the site between May 21 and June 7 the
following spring and prune all dead, diseased or injured branches from plants as
specified above. The contractor shall notify the City at least 1 week prior to
commencing pruning.
(ca) After watering on the day of planting, and throughout the maintenance period,
the contractor shall ensure that all plants are sufficiently, but not over, watered.
Trees shall receive a minimum of 10 gallons per diameter inch weekly or as
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specified on a tree protection plan.
(db) Wood chip mulch shall be placed in all planting beds, shrub areas and the sod-
free area of a 3-foot radius at the base of each tree. The mulch shall be spread
carefully and evenly to a depth of 3-4 inches. Mulch shall be removed 2” back
from the trunk. Shredded wood chip mulch shall be watered thoroughly two
times to aid in matting the mulch in place. The mulched areas shall be graded so
that the top of the mulch will be flush with the top of the curb, sidewalk, edging
or sod.
(e) Rock mulch shall be placed evenly to a minimum depth of 2 inches.
(fc) The contractor shall be responsible for damage to any underground utility,
irrigation line, paving, adjacent structures or other improvements. In the event a
pipe, line, rock formation, or other obstruction interferes with a plant location,
the contractor shall notify the Director to receive approval for a new plant
location.
(7) Moss Rock Installation Procedure
(a) The contractor shall notify the Director prior to moss rock placement work in
order to direct the contractor in a continuous operation of placing the rock with
the designated quantities. The contractor shall provide manpower and equipment
to place rock in 1 day and shall haul excess rock away from site.
(b) The contractor shall install rock boulders according to the layout and
configuration of the rock work as shown on the plans. Moss rock shall be set on
a compacted base (to 90 percent Proctor Density within 2 percent optimum
moisture content). Rockwork joints shall be made tight by butting natural faces
together in place. Soil grades shall be adjusted to stabilize rocks in position and
regraded in place to establish the placement of each rock so that they blend into
adjacent terrain. Rocks are to be placed by terracing or stepped layers to achieve
a naturalized effect. Finish grades shall be re-established as necessary.
10.04 Seeding/Sodding
(A) Description
(1) Seeding/sodding includes, without limitation, the planting and installation of grasses
(native or otherwise), preparation of soils and grading, and the methods to be applied in
planting and maintaining of grasses until full establishment is achieved.
(2) Medians less than 12 feet wide shall be landscaped with materials other than irrigated
turfgrass.
(B) Materials
(1) Fertilizer: Specified fertilizer shall be supplied in the original supplier's containers with
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label and order form showing composition and quantity. Fertilizer shall be intact, free-
flowing, dry and in quantity, as specified for sodded or seeded areas, as shown on the
plans. Fertilizer for sod and seeding soil preparation shall be a compound equivalent to
18-46-0 ph balance is more acidic 0-46-0 applied at the rate of 10 pounds per 1,000
square feet.
(2) Bluegrass: Bluegrass shall be Colorado-grown, 100 percent certified Kentucky
Bluegrass, of three improved bluegrass varieties complying with applicable Colorado and
Federal regulations. Reveille, Thermal Blue other approved drought resistant varieties.
Newport, Park, Delta and Common Kentucky Bluegrass are not acceptable varieties for
the sod mixture. The sod shall have a vigorous and healthy root system and top growth
and shall have been regularly fertilized, watered, mowed, sprayed and shall be free from
objectionable weeds and/or grasses. Sod strip shall have from 5/8 inch minimum to 1
inch maximum thickness of soil adhering to root system, cut into strips 18-inch maximum
width by 4 feet minimum length. Sod that has dried out, or sod with adhering soil that
breaks, tears or crumbles away will not be accepted. Sod cut for more than 24 hours shall
not be accepted. Sod rolls shall be kept moist, protected from sun, heat or wind in
transport and after delivery. Prior to cutting, the sod shall be evenly mowed for a blade
length of at least 1 inch but not more than 2 inches.
(3) Turf-type Tall Fescue: Turf-type tall fescue seed or sod shall be purchased from a
reputable seed dealer, complying with requirements specified. Seed mixture shall be of
at least three varieties (a maximum of five) of dwarf type tall fescue (i.e., Monarch, El
Dorado, Rebel Jr., Crew Cut, SR 8200, or other approved varieties).
(a) PLS shall not be less than 88 percent.
(b) Specified PLS shall be calculated as shown in Section (5)
(4) Buffalo Grass: Buffalo grass shall be either seed, plugs, or sod.
(a) Buffalo grass seed shall be purchased from a reputable seed dealer, complying
with the requirements specified. Seed mixture shall be “Texoka” or “Sharp's
Improved” or approved equivalent.
(i) PLS shall not be less than 75 percent.
(ii) Specified PLS shall be calculated as shown in Subsection (B)(5).
(b) Buffalo grass plugs or sod shall be 100 percent certified turf-forming variety 609,
or approved equivalent. Buffalo grass imported from states south of Colorado
may be approved due to the difficulty in establishing sod in the front range
climate.
(i) All sod shall be healthy, in vigorous condition, of natural green color,
free of disease and harmful insects. The sod shall be laid within 48 hours
of harvest.
(ii) Plugs shall be cut from sod as described in this Section. Nursery grown
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plugs are acceptable with prior approval by the Director.
(c) If sod is to be used for medians larger than 12 feet wide, Buffalo grass is
preferred.
(5) Native Seed: Native grasses and wildflowers for median plantings are listed in tables 10-
3 and 10-4. Native grass seed shall be purchased from a reputable seed dealer,
complying with requirements specified. Seed mixture shall be “Foothills” mix as
provided by Arkansas Valley Seed Company (303.320.7500), or approved equivalent.
(a) PLS shall not be less than 80 percent (average for the seed mix).
(b) Quantity of bulk seed required to provide the specified PLS shall be calculated
from purity and germination percentage rates listed on the lot tag of seed actually
purchased, using the following two formulas:
Purity Percentage x Germination Percentage = PLS Percentage
lbs. PLS specified per 1000 square feet = Bulk lbs.
required per
PLS percentage
1000 square feet
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Table 10-3: Wildflowers
Common Name
Latin Name
Blanket flower
Gaillardia aristata
Blue flax
Adenolinum (Linum) lewisii
Broom snakeweed Gutierrezia sarothrae
Bush sunflower Helianthus pumilus
Fringed sage Artemisia frigida
Greenleaf penstemon (blue mist) Penstemon virens
Nelson's larkspur Delphinium nelsonii
One-sided penstemon Penstemon secundiflorus
Prairie clover Dalea purpurea
Prairie coneflower Ratibida columnifera
Prairie sage (Sagewort) Artemisia ludoviciana
Prickly pear cactus Opuntia macrorhiza (compressa)
Rocky Mountain beeplant Cleome serrulataserrulate
Scarlet globe mallow Sphaeralcea coccinea
Spiderwort Tradescantia occidentalis
Spiny goldenweed Machaeranthera pinnatifida
Spotted gayfeather (Dotted gayfeather) Liatris punctatapunctate
Sulphur flower Eriogonum umbellatum
Western wallflower Erysimum asperum
White evening primrose Oenothera caespitosa
White yarrow (Woolly yarrow) Achillea lanulosa
Wild bergamot (Horsemint or Beebalm) Monarda fistulosa
Wild verbena Glandularia (Verbena) bipinnatifida
Yellow stemless evening primrose Oenothera howardii (brachycarpa)
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Table 10-4: Grasses
Common Name Latin Name
Type
Arizona fescue Festuca arizonica Turf
Big bluestem Andropogon gerardii Ornamental
Blue grama Chondrosum gracile (Bouteloua gracilis) Ornamental/Turf
Bluebunch wheatgrass Pseudoroegneria (Agropyron) spicatum Ornamental
Buffalograss Buchloe dactyloides Turf
Indian ricegrass Achnatherum (Orzyopsis) hymenoides Ornamental
Junegrass Koeleria macrantha Ornamental/Turf
Little bluestem Schizachyrium scoparium Ornamental
Mountain muhly Muhlenbergia montana Ornamental/Turf
Needle-and-thread Hesperostipa (Stipa) comata Ornamental
New Mexico feathergrass Hesperostipa (Stipa) neomexicana Ornamental
Prairie dropseed Sporobolus heterolepis
Prairie sandreed Calamovilfa longifolia Ornamental
Sand dropseed Sporobolus cryptandrus
Side-oats grama Bouteloua curtipendula Ornamental
Western wheatgrass Pascopyrum (Agropyron) smithii Turf
Table 10-54: Soil Amendment Mix Mechanical Analysis
Percent (%) Passing
Percent (%) Retained
2" Screen
100
0
1" Screen
90-100
0-10
½ " Screen
50-80
20-50
#100 Mesh Sieve
0-15
85-100
(4) Soil Amendment: Soil amendment for sod and seed areas, shall be manure compost, and
shall contain at least 50 percent organic matter. The mixture shall be free from clay
subsoil, sawdust, commercial wood products, stones, lumps, plants, roots, sticks, weed
stolons and seeds, high salt content, and other materials harmful to plant life. The
materials shall be coarsely ground and thoroughly mixed together to ensure an even
composition. Cow manure or mushroom compost shall be free from lumps, debris or
chemicals harmful to landscape plantings. The soil amendment mix shall have an acidity
from pH 5.5 to 8.0, and meet the mechanical analysis outlined in Table 10-34, “Soil
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Amendment Mix Mechanical Analysis,” of these Standards.
(5) Erosion Control Netting: Jute mesh erosion control netting or approved equivalent
shall be used.
(C) Construction Requirements
(1) Subgrade and Soil Preparation
(a) The contractor shall lay out and stake the boundary of all areas to be sodded,
seeded, or plugged prior to commencing any work. After Director approval of
finish grades, tThe contractor shall prepare the subgrade of all seeded or sodded
areas by discing or rototilling the soil to a depth of 6 inches. No ripping or
chiseling shall be allowed. No rototilling or discing is to be done within the
protection area of existing trees. After the subgrade has been completed, soil
preparation shall begin by spreading the soil amendment evenly within the
seeding or sodding limits at the rate of 3(56) cubic yards per 1,000 square feet. If
topsoil is used as the subgrade for sod or seed, soil amendment will not be
required. Soil amendment is not required in areas to be seeded with native
grasses.
(b) For sod, 0-46-0-18-46-0 fertilizer shall then be spread uniformly over the entire
area at the rates as specified for soil preparation. The area shall again be disced
or rototilled at right angles to the first tillage, then formed by rolling to provide a
proper seed bed or sodding surface. The sod or seed bed shall be totally free
from rock, debris, vegetable matter, noxious weeds or clay clods over ½ inch
diameter, prior to any sodding or seeding operations.
(2) Finish and Fine Grading
(a) Positive Surface Drainage: The contractor shall finish and fine-grade the project
area to establish an even and well-matched grade over the entire surface.
Positive surface drainage shall be assured, and there shall be no depressions,
subsequent settling or irregularities in the finished grade.
(b) Transitional Areas: At any transitional point or line where one plane intersects
another, such as from a sloping area or berm to a level area, a smooth and gentle
transition shall be made. There shall be no abrupt changes in grade. There shall
also be a smooth transition between existing turf and the new sod. The grade
elevations of the two areas shall be matching.
(3) Schedule: All seeding shall be scheduled between March 1 and October 15 unless prior
written approval from the Director has been obtained.
(a) No sodding and seeding shall take place during inclement weather.
(b) No sodding and seeding work shall commence until the adjacent site
improvements, pavements, irrigation installation and finish grading is completed.
The irrigation system shall have been tested and be in operating order prior to
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any seeding or sodding.
(c) The contractor shall barricade sodded area immediately after sod installation as
specified on the approved construction plans or in these Standards. The
barricade shall include the following:
(i) Standard construction lath at 5 foot intervals connected with three tiers of
colored plastic flagging.
(ii) “KEEP OFF THE SOD” signs attached to the barricading every 25 feet.
(4) Seeding
(a) Following approval of the seed bed by the Director, Sseeding shall be done with
a Brillion drill or approved mechanical seeder. Seed shall be evenly distributed
on a still day into a slightly moist seed bed. Seed shall be drilled 1/8 inch into
the prepared seed bed. If the slope is too steep to drill, seed shall be broadcast at
double the application rate and covered with 1/8 inch of soil with a harrow or
hand rake for small areas. The seeding shall be done in two separate applications
crossing the area at right angles to guarantee proper coverage. Drill seed across
slopes rather than up and down, following the contour to reduce erosion.
(i) Native grasses shall be seeded at a rate of 20 pounds PLS/acre when
drilled and 35 pounds PLS/acre when broadcast.
(ii) Buffalo grass shall be seeded at a rate of 3 pounds PLS/1000 square feet
when drilled and 5 pounds PLS/1000 square feet. when broadcast.
(iii) Turf type tall fescue shall be seeded at a rate of 6 pounds/1000 square
feet when drilled and 9 pounds/1000 square feet when broadcast.
(b) After seeding operations have been completed, the entire seeded area shall be
hydromulched with “Conwed 2000" or approved equal hydro mulch material.
The hydro mulch shall be applied by using mechanical hydromulcher, evenly
distributed on a still day. The hydro mulch material shall be applied at the rates
recommended by the manufacturer. Within 12 hours after seeding, the sprinkler
system shall be activated to moisten seeded areas to a depth of 1 inch. All seeded
areas shall be kept so moistened by frequent light watering until final acceptance
of the project or as required by City Land Use Regulations, and such watering
shall be the responsibility of the contractor.
(i) Protect seeded slopes (greater than 2.5 horizontal to one vertical) with erosion
control netting or other methods acceptable to the Director. Cover netting with
straw or other acceptable mulch.
(j) Seeding is not complete and will not be accepted until 70% coverage is achieved
with the intended species.
(5) Bluegrass Sodding
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(a) Sod shall be laid on a firm, premoistened bed with tight joints so that no voids
occur under or between strips. All end joints shall be staggered and the sod roll
length shall run perpendicular to all slope fall lines. Sod shall be tamped, rolled,
and watered immediately after sodding operations are completed.
(b) No sod shall be installed within a radius of 3 feet around any tree within the
project limits. Shredded wood chips shall be installed to a 3 inch depth in this 3
foot area. All rolls terminating at the project limits shall be cut in a straight line
unless otherwise specified and the exposed edge covered with topsoil. All sod
installed around planting beds shall be cut to conform to the shape of the bed as
shown on plan or laid out onsite. Sod shall be laid flush with paving, curbs and
irrigation heads and 1 inch below the top edge of steel edging.
(c) In the event that sod dries or shrinks, a mixture of screened topsoil and specified
bluegrass seed shall be brushed into the cracks and tamped flush. Excessively
shrunk sod (over 3/4 inch shrinkage) shall be replaced with new sod. Any sod
laid on slopes steeper than 3:1 (33 percent) shall be laid at a 90 degree angle to
the slope and held in place with two wooden dowels per sod piece.
(d) The contractor shall activate the sprinkler system to water sod immediately after
each section of sod is laid. The contractor shall operate the sprinkler to soak all
sod and the underlying soil to a depth of 2 inches and maintain this moisture
level until final acceptance. The contractor shall water the sod in the early
morning and late afternoon for the duration of this period.
(6) Buffalo Grass Sod
(a) Prior to sodding, the site should be lightly irrigated to alleviate “sod-wicking”
and desiccation. The sod shall be laid by staggering joints with all edges
touching. Installation shall be performed between April 1 to August 31.
Immediately following the laying of the sod, the sod should be rolled with a
roller, weighing at least 150 pounds, heavy enough to imprint the sod into the
soil.
(b) The contractor shall irrigate immediately after any sod installation, so that the
sod and underlying soil is completely wetted to a depth of 4 to 6 inches
(saturated). Subsequent irrigation shall be applied as necessary as determined by
daily inspection of the sod panels. Daily inspection should consist of manually
raising several sod panels and testing the level of moistness in the soil by
pinching the soil together. If the soil remains 'pinched' together, and is moist,
and the panel's sod pad is also moist, then the sod does not require watering that
day. If the soil, after being pinched, falls apart, the sod shall be irrigated to retain
the required moisture level. The sod soil pad and underlying soil should be moist
at all times.
(c) Rainfall received during the establishment period may reduce the irrigation
required. If temperatures exceed 95 degrees for periods of several days, the sod
may have to be inspected more frequently and additional daily irrigation cycles
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may be required. If the soil that has been sodded is extremely hard, or
compacted, and not easily saturated, or dries out quickly, the sod and soil shall be
kept consistently moist the first ten days.
(d) Normal establishment should display the following characteristics. Within 48
hours of installation the sod should turn a straw color, which is called a dormant
stage, although the roots would continue to grow while the top growth is
dormant. Within 5 to 7 days feeder roots should begin appearing. Within 14 to
21 days new green top growth should be seen and the sod should be firmly
rooted. Once this occurs, daily manual inspections would no longer be required.
Sod should then be watered 1½ inches per week for 2 to three months, to prevent
drought stress, until deeper rooting takes place.
(e) The contractor is to thoroughly discuss required installation, establishment and
post-establishment methods, irrigation, and maintenance requirements with the
sod supplier (specifically for sod maintenance - weed control/removal, i.e., what
chemical can safely be used, etc.).
(7) Buffalo Grass Plugs
(a) Plugs shall be planted on 12 inch centers with a requirement of at least nine (9)
plugs per square yard of ground. Plugging machinery must convert 16 x 24 inch
sod panels into plugs and plant in one operation. Each 16 x 24 inch sod panel
yields 24 4 inch square plugs, with a total of 81 plugs cut from a yard of sod. At
least 80 percent of the plugs shall be a 4 inch square plug (4 x 4 inches);
minimum acceptable size for the remainder of the plugs is 2 x 4 inches, nor
maximum size any larger than 4 inch x 4 inch. Coordinate equipment passes to
maintain parallel, evenly spaced rows. Immediately following plugging, the
plugs should be rolled with a roller, weighing at least 150 pounds, heavy enough
to imprint the plugs into the soil.
(b) All plugs shall be planted within 48 hours of harvest of the sod. All plugs shall
be healthy, in vigorous condition, of natural green color, free of disease and
harmful insects. Water after any portion of the plugging is complete, within 4
hours of planting, so that the plugs are completely wetted and the underlying soil
is wetted to a depth of 4 to 6 inches.
(c) All buffalo grass sod establishment, irrigation, and maintenance requirements
shall apply to plugs. Plugs will require more frequent manual inspection and
more frequent watering. After the initial establishment period, plugs should be
watered 1 inches per week until desired coverage is achieved.
10.05 Permanent Underground Irrigation System
(A) Description
Underground irrigation includes, without limitation, installing a complete underground permanent
irrigation system consisting of irrigation pipelines, sprinklers, valves, and controllers as part of
any landscaping project. Temporary irrigation systems will not be allowed unless approved by the
Director.
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(B) Materials
(1) Sprinkler System Components: All sprinkler system components shall be those of the
manufacturers specified in these Standards, or be an approved equivalent, and shall be
installed in accordance with these Standards.
(2) Sprinkler Heads: Pop-up rotary impact or stream spray sprinklers shall be used to water
sod and shrub areas, using full and part circle heads as specified on any approved
landscape plans. Requirements for the sprinklers include the following:
(a) Sprinklers shall provide coverage as specified on any approved landscape plans,
plus or minus 5 percent of the flow rate and 2 ½ feet within the design radius
during a low wind situation.
(b) Sprinkler heads shall meet the following specifications:
(i) Minimum pop-up height of 2-5/16 (6) inches (pop ups/MP rotators) 5”
larger rotors with heavy retract spring;
(ii) Part circle sprinklers shall be adjustable for any arc between 20 and 340
degrees;
(iii) Have built-in check valves in the head to control low head drainage and
reduce air compression in lines. The check valve shall be serviceable
from the top of the head without requiring excavation and removal of the
head from the riser.
(c) Sprinklers shall be vandal resistant, and shall have vandal-resistant cover screws
or no exposed screws in the cover.
(d) Sprinklers shall be tamper resistant to prevent changing the direction of throws
by means of locking friction collars, gear drives, and limited access features.
(e) Sprinklers shall have a drive mechanism that will ensure proper and even rotation
and coverage on 4:1 slopes.
(f) Sprinklers shall have rubber covers or similar protective devices.
(3) Bubblers: Requirements for bubbler heads shall include the following items.
(a) Heads shall operate properly between 10 psi and 80 psi;
(b) Heads shall have a molded plastic body with a ½ inch female pipe thread;
(c) Heads shall have a nozzle flow adjusting screw, providing fully open to
completely closed positions;
(d) Heads shall have a plastic basket screen to protect nozzles from clogging.
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(4) Automatic Control Valves
(a) Automatic electric remote control valves shall be slow acting diaphragm-type
electric solenoid valves. Solenoids shall be two-watt running, current 24 volt
AC, 50/60 cycle operation. The valve shall be slow opening and closing by
means of a “shunt” resistor to avoid damage from surge pressures. Valve flow
range shall be 1 to 200 gallons per minute depending on size with a pressure
range of 10 to 200 PSI.
(b) All valve bodies and bonnets shall be constructed of heavy case bronze with
accurately machined valve seat surfaces and internal parts. Inlet part of
diaphragm chamber shall have a removable screen for easy cleaning, accessible
without removing bonnet from valve body. Valve bonnets shall be equipped
with a slotted plug or bleed screw for manual operation of valves at any time
without energizing the solenoid, and a manual flow control stem.
(5) Isolation Gate Valves: Isolation gate valves for installation on main lines shall be of
brass construction, designed for 200 psi working pressures, and have solid disc, non-
rising stems with a heel and screwed ends. Gate valves 3 inches or larger shall be brass
or iron AWWA gate valves with rubber gaskets or mechanical joints.
(6) Quick-Coupling Valves: Anti Rotation Quick-coupling valves installed in main lines
shall be of a cast brass body construction, and have a self-closing and locking protective
cover. The throat shall incorporate a single keyway with positions for regulation of water
flow, with a flow range of 10 to 70 gallons per minute and a pressure range of 5 to 125
psi. Replaceable seals shall be provided at the valve seat and throat, and the internal parts
shall be removable for service. Installation on a main line in shall include a 10-inch
circular locking valve box over the coupler body. Size shall be 1 inch. Quick-coupling
valve keys shall have 1 inch male top pipe threads. Swivel hose ells shall be 1 inch
N.P.T. x 3/4 inch hose thread.
(7) Manual Drain Valves: The system shall be equipped with 3/4 inch curb stop manual
globe drain valves at all low points on main lines. Valves shall be of bronze construction
with threaded connections, cross handles, and operating keys. Install valves in a locking
valve box. Angle valves will not be accepted.
(8) Y-Strainers: Y-Strainers for installation on main line shall be bronze “Y” type strainers
with a screen mesh.
(9) Wire Connectors: All wire connections at electric control valves and all splices of wire
in the field shall be made using “snap-tits,” or an approved equivalent, wire connectors.
Significant requirements for connectors include the following items:
(a) Connectors shall be rated at 600 volts for PVC insulated copper wire,
Underwriters Laboratory listed, and water-resistant.
(b) Connectors shall consist of a PVC base socket, sealing plug, and wire crimping
sleeve and shall provide a permanent waterproof joint by using a silicone sealer
for joint makeup.
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(10) Controllers
(a) Automatic sprinkler controllers shall be completely automatic in operation, and
shall electrically start all sprinkler cycles and time the individual stations.
Controllers shall have standard 117 volt power inputs, 24.0 volt, 60 cycle outputs
with separate independent timing stations, 14 day programming, and be capable
of automatically starting a watering cycle at the beginning of any hour for 23
hours per day. Each station shall have an “OFF” switch for “0" time and
individual incremental timing control for 0 to 60 minute station timing. Each
station shall have an “ON-Repeat” switch for eliminating one or more stations
from initiating a repeat cycle on any or all stations after the normal watering
cycle has been completed. A 14 day clock shall be provided for maximum
programming versatility and any timer pins shall be of the captive type to prevent
loss. It shall be possible to operate controller manually and to select and operate
manually any station. All controls shall be capable of being manipulated at any
time in any sequence without damage to controller. The controller shall have the
ability for dual programming and shall have soil moisture sensing equipment.
(b) Soil moisture sensing equipment shall have an adjustable control module with an
override function, and at least two in-ground sensors/tensiometers. Sensors must
buffer salinity, and have the ability to withstand winter conditions without
removal.
(c) A reset circuit breaker shall protect each controller from damage due to excessive
current. A master “ON-OFF” switch shall provide for turning controller “OFF”
during rainy weather, while allowing day and hour clocks to continue in
operation. The controller shall have as standard built-in features an electrical
circuit to operate a master valve and moisture sensor circuit to allow operation of
controllers in conjunction with a moisture sensing device. Install valve output
surge protection arresters for control wiring and common.
(d) All wiring to and from controllers shall be through color-coded plugs and
sockets. Controller cabinets shall be locking, weatherproof type, constructed of
heavy gauge steel with corrosion resistant enamel finish inside and out.
(e) Controllers shall conform to NEC Class 2 requirements of 24 volt valves.
Controllers shall be for wall or pedestal mounting.
(11) Valve Boxes: Lockable Valve boxes shall be sized to provide maintenance access to all
valve and controller component. The underside of all control valve boxes shall be clearly
marked to indicate controller numbers and valve numbers.
(12) Pipe
(a) Main Line Pipes:
(i) Main pressure line pipe shall be NSF approved virgin polyvinyl chloride
pipe or HDPE. Pipe shall be suitable for use at maximum hydrostatic
working pressures of 200 PSI. Pipe shall be made from clean, virgin,
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NSF approved, type 1, grade 1 PVC, conforming to Astin Resin
specification D1784-60 and project standard D2241 for PVC 1120 SDR
26 or SDR 21. PVC pipe is to be belled end and solvent weld. Solvent
cement and primer shall be of the type prescribed by the manufacturer.
(ii) Gasket pipe and fittings shall be used for main lines 3 inches or larger.
Gasketed pipe shall be of the type prescribed by the manufacturer. No
insert gaskets or insert gasket fittings shall be accepted. Thrust blocks
shall be provided in accordance with pipe manufacturer's
recommendations.
(b) Marking and Declaration of Compliance: Pipe marking shall show the size,
series, identification, and manufacturer's trade name at intervals of not more than
20 feet. Pipe shall include the seal of approval of the National Sanitation
Foundation spaced at intervals required by NSF regulations.
(c) PVC Fittings: All pipe fittings shall be schedule 40 PVC (ASTM D2466 and
D1784). Solvent cement shall conform to ASTM D2564.
(d) Brass Pipe and Fittings:
(i) Brass pipe shall be 85 percent red brass, (ANSI) Schedule 40.
(ii) Fittings shall be medium brass, 125 pound class, screwed type.
(iii) Dielectric unions shall be used wherever a copper based metal (copper,
brass, bronze) is connected to an iron based metal (iron, galvanized and
stainless steel).
(e) Copper Pipe: Copper pipe shall meet the requirements of Type K, ASTM B88.
Fittings shall be copper or cast bronze. Silver solder shall be used for joints.
(f) Lateral Line Pipes: Pipe for rotary sprinkler laterals shall be NSF approved
HDPE polyethylene, rated at 8100 PSI, using sch 40 nylon insert fittings and
adjustable stainless steel clamps with stainless steel screws. All piping shall be
CS-256-63 ASTM D2239, PE 2306-100. 23 inch or larger class 200 -1” sch 40
lateral piping shall meet the standards for main line pipes.
(g) Static Pressure Reduction: Static pressure on the main line shall be relieved by
the installation of a “master” automatic control valve.
(13) Risers: Rotary pop-up sprinklers shall have an adjustable swing joint riser assembly
consisting of Schedule 80 PVC nipples, and marlex and Schedule 40 PVC ells.
(14) Irrigation Sleeves: All horizontal sleeves under paved areas and vertical sleeves shall be
PVC Class 200 pipe, or SDR 35 glue joint and glued 4 inch diameter for lines 2 inches
and smaller, and 6 inch diameter for lines 2 ½ inches to 3 inches. A separate 2 inch
diameter sleeve for control valve wires shall be laid under any new pavements. This
sleeve shall be placed next to the main line sleeve.
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(15) Backflow Prevention Device: Backflow prevention devices shall be installed in
accordance with these Standards and B.R.C. 1981.
(16) Electrical Copper Wires: Electrical copper wires from valves to controller shall be 14
gauge or larger PVC-insulated copper and UNDERWRITERS LABORATORY approved
for direct burial. Use 10 inch valve boxes for all wire splice locations. Control wires
shall be red and common wires shall be white.
(17) Drip Valve Assemblies: Drip valve assemblies shall have strainers with a 120 mesh
nylon screen and ½ inch blow-out. Pressure reducing valves shall have manual adjusting
nuts.
(18) Drip Emitters and Tubing: Drip emitters shall use drip tubing conforming to ASTM
D1248 and ASTM D3350. Capillary tubing shall have 1/8 inch i.d.
(19) Drip Line Blow Out Stubs: Drip line blow out stubs shall be installed at all ends of drip
tubing.
(C) Construction Requirements
(1) Applicable Standards
(a) All work involving standard plumbing systems shall be executed by a licensed
and bonded plumber. Electrical services to controllers shall be installed by a
licensed electrician. All work shall be executed according to the B.R.C. 1981,
and these Standards. The contractor shall schedule inspection of electrical
services to controllers with the City and allow at least 7 working days for
subsequent approval and connection to the power source by the Public Service
Company. The contractor shall furnish any additional material and labor when
required to comply with the B.R.C. 1981, and these Standards.
(b) The contractor shall perform a leakage test on all systems on the site at normal
working pressures.
(c) The contractor shall guarantee irrigation application in accordance with any
approved landscape plan; any unwatered areas due to poor layout, placement of
or insufficient sprinklers shall be corrected by the contractor at their expense.
(d) Work shall be in accordance with good practices prevailing in the piping trades.
(e) All work shall be protected from vandals or flooding during construction.
(2) Layout of Work: Before any installation operations are started, the contractor shall
completely stake out the irrigation system on the site. Any discrepancies in irrigation
water coverage shall be reported and corrected at this time.
(3) Schedule
(a) No sprinkler system construction shall take place during wet weather or when
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temperatures are less than 340 degrees Fahrenheit.
(b) All required sleeving shall be performed prior to any paving operations. All
procedures necessary for the insertion and installation of irrigation pipe and wires
into sleeves shall be performed after paving operations have been completed,
with 18” for lateral and 30” maximum depth.
(c) Installation of the system shall not take place until all earthwork has been
substantially completed and compacted and all other site improvements,
pavements, etc. have been completed.
(4) Trenching and Piping
(a) The contractor shall perform all necessary excavation for installation of their
work. Over-excavations shall be backfilled and hand tamped prior to installing
pipe. Any pumping, shoring, or bracing shall be provided by contractor.
(b) Manufacturer's specifications covering installation of their material shall be
followed. Underground lines up to 2 inches shall have minimum horizontal
clearance of 2 inches of each other, and larger lines shall have a clearance of 4
inches. No sprinkler lines shall be stacked vertically in a common trench. Lines
shall have minimum horizontal clearance of 12 inches from the lines of other
trades. There shall be a minimum 2 inch vertical clearance between any lines
crossing 45 degrees - 90 degrees. Minimum cover over lateral piping shall be 12
inches, or to a depth to accommodate valves and other equipment, whichever is
greater. All PVC main line shall be at 18-inch minimum depth of bury. PVC
main line is to be encased in sand 4 inches on all sides.
(c) Where trenches and lines run adjacent to existing irrigation lines and properties,
damage to these shall be avoided and shall be restored to their original condition
(d) When pipe laying is not in progress, or at end of each day, pipe ends shall be
closed with tight plug or cap, or taped with PVC pipe wrap. All work shall be
performed in accordance with good practices prevailing in the piping trades.
(e) Tunneling will be permitted where the pipe must pass under any obstruction that
cannot be removed. In backfilling the tunnel, the final density of the backfill
must match that of the surrounding soil. It shall be acceptable to use a casing of
suitable diameter that shall be installed first by tunneling or jacking, and the pipe
shall then be laid through the casing, observing the same precautions as though it
were installed in open trench.
(f) Trenches shall be cut to true line and grade, and shall be excavated so that the
pipe shall be supported uniformly. The contractor shall be responsible for
staking the trench lines. Minimum grade of piping to drain shall be 3 inches/100
feet.
(g) If ground water is encountered during trench excavation above the elevation of
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the bottom of the pipe grade, such water shall be drained until the pipe has been
installed. Pipe joints and open ends shall be plugged to prevent ground water
from entering the pipe.
(h) Thrust blocks shall be installed behind all gasketed fittings, in line valves, and
caps. Gasket pipe fittings shall be installed according to manufacturer's
recommendations. Concrete for thrust blocks shall cure for 72 hours before
pressure is applied to the system.
(5) Threaded Joints
(a) Field-threading of plastic pipe or fittings shall not be permitted. Only factory-
formed threads shall be used.
(b) Factory-made nipples shall be used wherever possible. Field-cut threads in
metallic pipe will be permitted only where absolutely necessary. When field
threading, cut threads accurately on axis with sharp dies.
(c) All threaded joints shall be assembled with pipe joint compound consisting of
liquid Teflon. The compound is to be applied to male threads only.
(d) Where assembling soft metal (brass or copper) or plastic pipe, strap type friction
wrenches shall be used; metal-jawed wrenches shall not be used.
(6) Sleeves
(a) The contractor shall furnish and install sleeves of appropriate size, depth, and
location to accommodate all irrigation pipe beneath any paved surfaces prior to
pipe installation as specified herein, unless they have been previously installed.
Where irrigation lines run under proposed paved surfaces, the contractor shall
sleeve the lines a distance 2 feet beyond the edge of the surface. Sleeves shall be
PVC Class 200 pipe/SDR 35 glue joint-glued.
(b) Installation of sleeves shall precede construction paving. Sleeves shall be
encased in sand 4 inches on all sides, with backfill compacted to 95 percent of
standard Proctor density. Sleeves shall be buried at a depth of 18 inches.
Separate sleeves placed at the 18 -inch bury depth shall be provided for wires
passing under paved sections. All sleeves installed under parking lot or street
shall be flow-filled
(c) All sleeves shall be marked by the placement of nylon rope, or an approved
equivalent marking material.
(7) Backfilling
(a) Trenches shall not be backfilled until all required tests on the system have been
completed and until the line has been inspected and approved by the Director.
Trenches shall be carefully backfilled with suitable materials, free from stones
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larger than 2 inches in maximum dimension, by depositing the material in 6 inch
layers and thoroughly compacting the backfill to 95 percent of standard Proctor
density.
(b) Ponding and/or jetting may be used only if prior approval is obtained and only
when the backfill material is sandy or gravelly. An excess of water shall be
avoided in order to prevent disturbance of the earth under and around the pipe.
Likewise the amount of water used shall be controlled so as not to risk “floating”
the pipe out of position. Adequate dikes shall be constructed along the trench to
retain and guide the water. When jetting is used, jets shall be of an approved
design and of sufficient length to reach the bottom of each layer and the water
supply shall be continuous.
(c) Site excavation material will generally be considered satisfactory for backfill
purposes provided that backfill materials are free from rubbish, vegetable matter,
frozen materials, or stones larger than 2 inches in maximum dimension. Any
material not meeting these specifications for backfill shall be removed from site.
(d) Backfilling shall not be performed in freezing weather. All trenches shall be left
slightly mounded to allow for settlement after the backfilling is completed. If
sinking of the trenches occurs, it is the responsibility of the contractor to correct
such conditions.
(8) Manual Drain Valves: Manual drain valves shall be located, furnished, and installed by
the contractor at all low points on sprinkler lines. A drain sump of not less than 6 cubic
feet of 11/2”3/4 inch washed gravel shall be installed surrounding each drain valve. All
manual drain valves are to be installed with drain valve sleeves.
(9) Electric Control Valves
(a) Electric control valves shall be automatic and purchased from the manufacturer
specified, or be an approved equivalent, matching size, model and quantity as
listed on an approved landscape plan. All control valves shall be installed at the
locations shown on the approved landscape plan.
(b) Electric control valves shall be installed in accordance with the manufacturer's
recommendations. All valves shall have sufficient clearance from adjacent
obstructions to provide accessibility for maintenance. All valves shall be
installed at sufficient depth to provide at least 6 inches cover to finished grade.
Only one control valve per valve box shall be installed.
(c) Control wire shall have an 18-inch expansion loop at each valve and elsewhere as
necessary to prevent possible wire breaks. Where more than one control wire is
located in the trench, the wires shall be taped together at 20 foot intervals to
maintain orderly and efficient installation. All control wires shall be placed
carefully alongside and slightly below the main line for protection. Control wires
not protected by the irrigation main shall be laid in a 2 inch PVC class 200
sleeve. Electrical control wires shall be extended along the irrigation main and
connected to the controller.
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(d) Electrical control wires shall be connected with snap-tits connectors. Splicing
will be permitted only on runs exceeding 500 feet in length, and shall be located
at valve locations. Wires shall be bundled and taped at 20 foot intervals. A
minimum wire loop of 24 inches shall be provided at each control valve, splice,
and every 100 feet of wiring. Two spare #14-1 wires, blue in color, shall be
installed along the entire length of the main line from the controller to farthest
control valve on each and every branch of the main line.
(10) Pressure Reducing Valves: Pressure reducing valves (PRV) shall be installed to ensure
proper operating pressures at sprinkler locations.
(11) Valve Boxes: All automatic control valves, pressure reducing valves, backflow
prevention devices, isolation gate valves, manual drain valves, and quick-coupling valves
are to be installed in valve boxes. The valve box and cover shall be flush with the final
grade and level. The valve box shall be installed with a 4”2 inch layer of 1 1/2”washed
gravel on the sides and below the box. If the box encloses a double check valve
assembly, the gravel layer below the box shall be equal in volume to the volume of the
box.
(12) Quick-Coupling Valves: Quick-coupling valves shall be installed in conformance with
these Standards. Additional quick-coupling valves shall be located every 200 feet along
the main line. All valves shall be installed in separate 10-inch circular valve boxes
placed flush with the final grade and level.
(13) Isolation Gate Valves: Isolation gate valves on the main line shall be plumb with
finished grade and installed in a valve box placed flush with the final grade and level.
Extensions may be added onto the valve box as necessary to level box with finish grade.
(14) Sprinklers
(a) Installation of sprinklers includes furnishing, installing, and testing, risers,
fittings, sprinkler heads, bubblers, and other sprinkler system components in
accordance with an approved landscape plan. Sprinkler piping shall be
thoroughly flushed before the installation of the sprinkler heads and bubblers.
(b) Sprinkler heads shall be set plumb and level with finished grade at locations
shown on an approved landscape plan. Sprinklers shall be set 12”3 inches behind
concrete improvements such as curb and gutter or sidewalks. Sprinklers installed
where grass has not been sodded shall be installed on temporary risers extending
minimum 3 inches above grade. After finished grades are established and the
ground has settled, the contractor shall lower sprinklers to finished grade.
(c) Bubblers shall be set plumb and level before mulch is installed.
(d) Rotary pop-up sprinklers on swing joint risers shall be installed as shown in these
Standards and may be adjusted in the field as necessary.
(15) Drip Valve Assemblies: Installation of drip valve assemblies shall in conformance with
09.12.22 TAB Agenda 6 DCS Transportation
Page 118 of 143
Effective: November 16, 2000TBD DESIGN AND CONSTRUCTION STANDARDS
10-31
these Standards.
(16) Drip Emitters and Tubing: Installation of drip emitters and tubing shall be installed in
conformance with these Standards at a depth of 4 inches below top of grade. For this
purpose, top of grade does not include mulch or rock layers. Drip line blow-out stubs are
to be installed at all ends of drip tubing. Drip tubing may be installed in turf areas as
lateral piping.
(17) Controllers and Related Work: The controller shall be mounted on three wolmanized
CCA 6 inch x 6 inch ties, set at least 24 inches below grade and a maximum of 18 inches
above grade. The controller shall be located as shown on an approved landscape plan,
and be mounted inside a locking, weather-proof metal cabinet. The contractor shall
provide and install a 15-amp electrical circuit breaker in a locking, weatherproof box.
The contractor shall wire the circuit breaker and controller and run wire to the Public
Service Company pull box, leaving an 18-inch tail of wire in the pull box or sleeve.
After connection, the contractor shall notify the City’s Inspection Services to inspect
controller and circuit breaker wiring prior to notifying Public Service Company to
connect power to the wiring. The contractor shall be responsible for manual operation of
the sprinkler system until power is connected. All wiring shall be performed by a
licensed electrician.
(18) Testing and Adjusting
(a) All main lines having continuous pressure shall be tested at a minimum pressure
of 1200 psi. Visual inspection shall be performed and any leak shall be repaired.
Repaired lines shall be retested until no leakage is occurring.
(i) Zone lateral lines shall be tested at the design operating pressure of the
zone. Any leaks found shall be repaired and the zone retested. All
sprinklers shall be operating at the same pressure plus or minus 7
percent.
(ii) The entire irrigation system shall be tested at normal working pressure
for leaks in the system and retested until no leakage is occurring. The
pressure test shall be performed under the observation of the Director for
final approval.
(iii) After testing, the entire irrigation system shall be thoroughly flushed
with at least 100 percent of operating flow passing through each pipe,
beginning with larger mains and continuing through smaller lines in
sequence.
(b) The entire system shall be “fine-tuned” by regulating valves, adjusting patterns
and breakup arms, setting pressure reducing valves at proper pressure and
similar, to provide optimum and efficient coverage.
(c) Final inspection shall include observation and approval by the Director of the
performance, method of operation, and coverage of the irrigation system.
09.12.22 TAB Agenda 6 DCS Transportation
Page 119 of 143
DESIGN AND CONSTRUCTION STANDARDS Effective: November 16, 2000TBD
10-32
(d) The contractor shall furnish two sets of keys for all quick-couplers, manual drain
valves, gate valves, and controllers as well as padlocks and keys for controller
circuit breaker boxes, two sprinklers and nozzles of each type, hose ells for all
quick couplers, and all related loose parts necessary to operate the system, as part
of the final acceptance by the Director.
(19) Record Drawings (As-Builts): Upon completion of improvements and prior to final
acceptance, the contractor shall submit as-built drawings of the irrigation system to the
Director. The as-built drawings shall comply with the requirements of Subsection
1.03(G), “As-Built Drawings,” of these Standards, and shall include the location of
following items:
(a) Connection to existing water lines.
(b) Routing of sprinkler pressure lines (maximum 100 feet along routing).
(c) Sprinkler control valves.
(d) Quick coupling valves.
(e) Drain valves.
(f) Drip line blow-out stubs.
(g) Control wire routing if not with pressure main line.
(h) All gate valves.
(i) Other related equipment as directed by the City Manager.
(20) Operation Instruction: Prior to final acceptance of improvements, the contractor shall
submit three written sets of operating instructions, with cut sheets of all products, and a
guideline summer watering program.
(21) Controller Charts
(a) Controller charts shall be prepared for the Director once record (as-built)
drawings have been accepted.
(b) A controller chart shall be provided for each automatic controller installed.
(c) The controller chart may be a reproduction of the record drawing, if scale permits
fitting of the chart to the controller door. If photo reduction prints are required,
the reductions shall be sized to ensure full legibility.
(d) The controller chart shall represent the actual “as-built” system, showing the
specific area covered by that controller.
09.12.22 TAB Agenda 6 DCS Transportation
Page 120 of 143
Effective: November 16, 2000TBD DESIGN AND CONSTRUCTION STANDARDS
10-33
(e) The controller chart shall identify the area of coverage of each remote control
valve, using a distinctly different pastel color on drawing over the entire area of
coverage.
09.12.22 TAB Agenda 6 DCS Transportation
Page 121 of 143
Created: 2022-03-23 12:36:44 [EST]
(Supp. No. 150)
Page 1 of 5
9-9-7. Sight Triangles.
(a) Sight Triangle Required: Where a driveway intersects a public right-of-way or where property abuts the
intersection of two public rights of way, unobstructed sight distance as described in subsection s (c) through
(e)of this section shall be provided at all times within the sight triangle area on the property adjacent to the
intersection in order to ensure that safe and adequate sight distance is provided for the public use of the
right-of-way.
(b) Obstruction Prohibited: No person shall place or maintain any structures, fences, landscaping, or any other
objects within any sight triangle area described in subsection s (c) through (e) of this section that obstructs or
obscures sight distance visibility through such structures, fencing, landscaping, or other objects by more than
twenty-five percent of the total view in the vertical plane above the sight triangle area between a height of
thirty inches and ninety-six inches above the roadway surface, except for the following:
(1) Landscaping, structures, or fences that protrude no more than thirty inches above the adjacent
roadway surface may be permitted within the sight triangle area.
(2) Trees may be planted and maintained within the sight triangle area if all branches are trimmed to
maintain a clear vision for a vertical height of ninety-six inches above the roadway surface and the
location of the trees planted, based on the tree species expected mature height and size, does not
obstruct sight visibility by more than twenty-five percent of the sight triangle area.
(c) Sight Triangle Area: For purposes of this section, the sight triangle area for a driveway intersecting with the
public right-of-way is:
(1) Driveways intersecting with a public street without a public sidewalk : The area formed at a corner
intersection of public right-of-way and a driveway, whose two sides are fifteen feet, measured along
the right-of-way line of the street and the edge of the driveway, and whose third side is a line
connecting the two sides (see Figure 9-7 of this section);).
(2) Driveways intersecting with a public street with a public sidewalk: The area formed at a corner
intersection of a public sidewalk and a driveway, whose two sides are fifteen feet, measured along the
edge of the public sidewalk and the edge of the driveway, and whose third side is a line connecting the
two sides (see Figure 9-7a of this section).
(3) Driveways intersecting with a public street with a public multi-use path: The area formed at a corner
intersection of a public multi-use path and a driveway, whose sides are measured ninety-six feet along
the edge of the multi-use path and fifteen feet measured along the edge of the driveway, and whose
third side is a line connecting the two sides (see Figure 9-7b of this section).
(d) Sight Triangle Area: For purposes of this section, the sight triangle area for an alley intersecting with the
public right-of-way is:
(1) Alleys intersecting with a public street without a public sidewalk: The area formed at a corner
intersection of an alley public right-of-way and a street right-of-way whose two sides are fifteen feet,
measured along the right-of-way line of the alley and the right-of-way line of the street, and whose
third side is a line connecting the two sides (see Figure 9-7 of this section); or
(2) Alleys intersecting with a public street with a public sidewalk: The area formed at a corner intersection
of an alley and the public sidewalk, whose two sides are fifteen feet, measured along the edge of the
09.12.22 TAB Agenda 6 DCS Transportation
Page 122 of 143
Created: 2022-03-23 12:36:44 [EST]
(Supp. No. 150)
Page 2 of 5
alley and the edge of the public sidewalk, and whose third side is a line connecting the two sides (see
Figure 9-7a of this section).
(3) Alleys intersecting with a public street with a public multi-use path: The area formed at a corner
intersection of an alley and public multi-use path, whose sides are measured fifteen feet along the
edge of the alley and ninety-six feet measured along the edge of the multi-use path, and whose third
side is a line connecting the two sides (see Figure 9-7b of this section).
(2)Alleys: The area formed at a corner intersection of an alley public right-of-way and a street right-of-way
whose two sides are fifteen feet, measured along the right-of-way line of the alley and the right-of-way
line of the street, and whose third side is a line connecting the two sides (see Figure 9-7 of this section);
or
Figure 9-7: Sight Triangle Area at the Intersection of a Driveway or Alley and a Street
(without a sidewalk or multi-use path)
Figure 9-7a: Sight Triangle Area at the intersection of a Driveway or Alley and a Street with a sidewalk.
09.12.22 TAB Agenda 6 DCS Transportation
Page 123 of 143
Created: 2022-03-23 12:36:44 [EST]
(Supp. No. 150)
Page 3 of 5
Figure 9-7b: Sight Triangle Area at the intersection of a Driveway or Alley and a Street with a multi-use path
The shaded area is required to be kept free of all structures, landscaping, fences, and other materials. The triangle
is measured from the property line within alleys and the edge of pavement for driveways, as in this example.
(3e) Streets: The area formed at a corner intersection of two public rights-of-way lines defined by a width of
dimension X and a length of dimension Y as shown in Table 9-9 and Figure 9-8 of this section. The Y
dimension will vary depending on the speed limit and configuration of the intersecting street,
andstreet and is outlined in the table below. The X distance shall be thirteen feet measured
perpendicular from the curb line of the intersecting street. This triangular area is significant for the
determination of sight distance requirements for right angle intersections only.
Figure 9-8: Sight Triangle at Intersection of Streets
The shaded area is required to be kept free of all structures, fences, landscaping and other materials. The size of the
sight triangle is based on the size of the road and speed limit, as shown in the table below.
TABLE 9-9: SIGHT TRIANGLE REQUIREMENTS
Lane
Usage
Additional Facilities Speed Limit Y Distance (Left) Y Distance (Right)
2
lanes
None 25 mph 155 feet 105 feet
30/35 mph 210 feet 145 feet
Bike lane or on-street parking 25 mph 110 feet 85 feet
30/35 mph 150 feet 115 feet
09.12.22 TAB Agenda 6 DCS Transportation
Page 124 of 143
Created: 2022-03-23 12:36:44 [EST]
(Supp. No. 150)
Page 4 of 5
Bike lane and on-street parking 25 mph 90 feet 75 feet
30/35 mph 125 feet 100 feet
3 or 4
lanes
None 25 mph 155 feet 80 feet
30/35 mph 210 feet 110 feet
40/45 mph 265 feet 135 feet
Bike lane or on-street parking 25 mph 110 feet 65 feet
30/35 mph 150 feet 90 feet
40/45 mph 195 feet 115 feet
Bike lane and on-street parking 25 mph 90 feet 60 feet
30/35 mph 125 feet 80 feet
40/45 mph 160 feet 100 feet
5 or
more
lanes
None 25 mph 155 feet 60 feet
30/35 mph 210 feet 85 feet
40/45 mph 265 feet 110 feet
Bike lane or on-street parking 25 mph 110 feet 55 feet
30/35 mph 150 feet 75 feet
40/45 mph 195 feet 95 feet
Bike lane and on-street parking 25 mph 90 feet 50 feet
30/35 mph 125 feet 65 feet
40/45 mph 160 feet 85 feet
(fd) Modifications: The requirements of this section may be modified by the city manager, pursuant to Section 9-
2-2, "Administrative Review Procedures," B.R.C. 1981, if accepted engineering practice would indicate that a
modified visibility distance, either greater or lesser, would be acceptable or necessary for the safety of
pedestrians, motorists, and bicyclists.
(ge) Violations: No person shall violate or fail to prevent or remedy any violation of the provisions of this section
on such property. When a violation of this section is observed, the city manager will provide a written notice
to correct the condition to the property owner or occupant, whichever is applicable. Personal service of such
notice or mailing such notice to the last known address of the owner of the premises by certified mail shall
be deemed sufficient service. Any such notice shall describe the violation, describe the corrective measures
necessary, and set forth a time limit for compliance, dependent upon the hazard created, which time limit
shall not be less than seven days from the service of the notice.
(hf) Failure to Comply: In the event that there is failure to comply with the notice when the time limit prescribed
therein has expired, the city manager may trim or cause to be trimmed, or otherwise remove the obstruction
described in the notice. Such action shall not preclude any prosecution for violation of the terms of this
section. The costs of such action shall be paid by the property owner, and, if not paid, may be certified by the
city manager to the county treasurer for collection as taxes.
(ig) Public Nuisance: Notwithstanding any other provision in this section, any landscaping, structure, fence or
other obstruction which the city manager deems as an immediate and serious danger to the public, is hereby
declared a public nuisance and shall be trimmed or removed within twenty-four hours after notification by
the city manager. If the property owner or occupant fails to do so, the city manager may trim or remove the
nuisance. The costs of such action shall be paid by the property owner, and, if not paid, may be certified by
the city manager to the county treasurer for collection as taxes
Ordinance Nos. 5986 (1998); 7522 (2007); 8005 (2014)
09.12.22 TAB Agenda 6 DCS Transportation
Page 125 of 143
Created: 2022-03-23 12:36:44 [EST]
(Supp. No. 150)
Page 5 of 5
09.12.22 TAB Agenda 6 DCS Transportation
Page 126 of 143
TRAVEL LANE
BIKE LANE
SIDEWALK
BIKE LANE
RMP
LEGEND:
FLEX POST DELINEATOR
GREEN PAVEMENT MARKING WITH
EMBEDDED WHITE BIKE SYMBOL
DIRECTIONAL INDICATOR STRIP (SEE DRAWING NO. X.XX.X)
ACCESSIBLE RAMP SLOPE (RMP) = 7.8% TYP (8.3% MAX, 4% MIN)
BIKE RAMP
8° - 18°7'NOTES:
1. DESIGN PLANS SHOULD BE CONSULTED FOR VARIATIONS
2. SEE CITY OF BOULDER DESIGN AND CONSTRUCTION STANDARDS,
SECTION 2.07, TABLE 2.5 FOR STANDARD LANE WIDTHS
3. BIKE LANE TAPERS PREFERRED AT 7:1 SHIFT, MINIMUM 3:1 SHIFT IN
CONSTRAINED LOCATIONS WHERE SPEED IS ≤ 13 MPH
4. BIKE RAMPS PREFERRED TO HAVE ACCESSIBLE SLOPE, BUT NOT
REQUIRED
5. FOR BIKE LANES AT SIDEWALK ELEVATION WITHOUT BUFFER
TREATMENT, 1' MINIMUM DIRECTIONAL INDICATOR STRIP WITHIN THE
SIDEWALK; TYPICALLY THIS IS LOCATED 1' FROM THE EDGE OF THE
BIKE LANE
SIDEWALK BUFFERSUPPLEMENTAL DRAIN INLET
(AS REQUIRED)
DIRECTIONAL INDICATOR STRIP,
SEE NOTE 5
CHAMFERED CURB
ALONG ENTIRE RAMP
CUSTOM BIKE
ONLY SIGN
R3-17
CUSTOM OM3-R
OBJECT MARKER
42" FLEXABLE
DELINEATOR 18"12"24"120" (10')
12"
PRE-CAST CONCRETE CURB
PLAN VIEW
21"
O.C.
27"
O.C.
27"
O.C.
21"
O.C.12"
38"6"32"6"38"EQVARIES 12" - 24"EQLIFTING HOOK (TYP)
LIFTING POINT AND
DRAINAGE SLOT
2"x6" (TYP)
ANCHOR ROD (TYP)NOTES:
1. DESIGN PLANS SHOULD BE CONSULTED FOR VARIATIONS
2. DRILL AND EPOXY SMOOTH 1" DIA. STAINLESS STEEL ANCHOR
RODS. FOR CONCRETE PAVEMENT, ANCHORS SHALL BE A
MINIMUM OF 3" CLEAR FROM ALL JOINTS
6" MIN (CONC PVMT)
12" MIN (HMAC PVMT)
PRE-CAST CONCRETE CURB
SECTION VIEW
H/2
H= 6"
3"
VARIES 12" - 24"
1.5" CLEAR
MIN (TYP)
1" R (TYP)
1" DIA. STAINLESS STEEL
ANCHOR RODS, RECESSED
1
4" (SEE NOTE 2)
#4 LONGITUDINAL
BARS @ 6" O.C.
#4 BARS
@ 24" O.C.
09.12.22 TAB Agenda 6 DCS Transportation
Page 127 of 143
NOTES:
1. DETECTABLE DIRECTIONAL STRIP MUST BE "FEDERAL YELLOW",
UNLESS OTHERWISE APPROVED BY THE ENGINEER OF RECORD.
2. STRIP CENTERLINE MUST BE PARALLEL TO THE ALIGNMENT OF
THE PEDESTRIAN ACCESS ROUTE.
3. DESIGN PLANS SHOULD BE CONSULTED FOR VARIATIONS
DIMENSION RANGE (IN.)
B1 0.90 - 1.20
B2 B1 + 0.20
H1 0.18 - 0.20
H2 0.05 MAX.
12"
PLAN
1.5"
3" (TYP)
VARIES
B
B
A A
SECTION A-A
SECTION B-B
VARIES
H2
H1
B2
B1
CONCRETE
SURFACE
09.12.22 TAB Agenda 6 DCS Transportation
Page 128 of 143
LEGEND:
PEDESTRIAN
ACCESSIBLE ROUTE (P.A.R.)
NOTES:
1. APPROXIMATE LOCATION OF CROSSWALK, SIDEWALK, AND CURB RAMPS
SHOWN. COMPLETE DESIGN REQUIRED AS PART OF CURB EXTENSION, TO
BE APPROVED BY CITY ENGINEER
2. STREET SECTION SHALL BE REVIEWED FOR IMPACTS OF PROPOSED CURB
EXTENSION GEOMETRY AND ELEVATIONS, INCLUDING INTERFACE WITH
EXISTING STREET CROSS SECTION. INSTALLATION OF CURB EXTENSION
CAN AFFECT DRAINAGE CAPACITY, AND MUST BE REVIEWED AND
APPROVED BY CITY ENGINEER IN WRITING ON A CASE-BY-CASE BASIS.
3. THE REVERSE CURVES AT EACH END OF THE PARKING POCKET SHALL BE
TANGENT TO EACH OTHER AND EACH CURB SHALL BE TANGENT WITH THE
CURB LINE CONTINUING IN EACH DIRECTION
4. THE LENGTH OF THE EXTENSION IS MEASURED AS 20' FROM THE CLOSEST
EDGE OF THE CROSSWALK, WHICH IS TYPICALLY DEFINED AS THE
CLOSEST POINT OF THE CURB RAMP THROAT OR THE MARKED
CROSSWALK WHEN PRESENT. ANY REDUCTION IN LENGTH SHALL BE
APPROVED BY CITY ENGINEER.
5. CURB EXTENSION DESIGN SHALL ENSURE POSITIVE 0.7% PREFERRED, 0.5%
MIN, DRAINAGE SLOPE AT ALL POINTS ALONG NEW FLOW LINE.
6. IF THERE IS AN EXISTING OR PROPOSED BUS STOP OR DRIVEWAY AT THE
CORNER, THE LENGTH OF THE EXTENSION SHOULD BE INCREASED TO
ACCOMMODATE THE FULL LENGTH OF THE BUS STOP/DRIVEWAY. THE
WIDTH AND LENGTH OF THE EXTENSION WILL BE APPROVED BY CITY
ENGINEER.
7. LIMITS OF STREET CUT AND PATCHING SHALL BE SET TO ENSURE THAT
THE PEDESTRIAN ACCESSIBLE ROUTE (P.A.R.) WITHIN THE STREET (THE
CROSSWALK) IS NOT ADVERSELY AFFECTED BY CAUSING ANY P.A.R.
DESIGN ELEMENTS TO BE EXCEEDED.
8. REFER TO DRAWING NO. 2.07 A-K FOR CURB RAMP DETAILS
FLOW LINE, SEE NOTE 5
20' MIN,SEE NOTE 44' MIN - 8' MAX
CURB EXTENSION
15' R (TYP), SEE NOTE 3
CURB EXTENSION AMENITY ZONE, SEE DRAWING
NO. X.XX.X FOR OPTIONS AND PLANS FOR DETAILS
SUPPLEMENTAL DRAIN
INLET, SEE NOTE 2
OUTER CURB RAMP WINGS SHOULD BE
PLACED IF CURB EXTENSION AMENITY ZONE
IS WALKABLE OR IF DESIRE LINE WARRANTS
REFER TO DRAWING NO. X.XX.X FOR SECTION
NO PARKING SIGN
R7-1 (RIGHT)
FLOW LINE,
SEE NOTE 5
EXISTING FACE
OF CURB, TYP
FLOW LINE,
SEE NOTE 5
NO PARKING SIGN
R7-1 (LEFT)
FLEX POST
DELINEATOR
09.12.22 TAB Agenda 6 DCS Transportation
Page 129 of 143
CURB EXTENSION SECTION W/
STEEP ROAD CROSS SLOPE AND
WALKABLE EXTENSION AREA
CURB EXTENSION SECTION W/
LANDSCAPED EXTENSION AREA
CURB EXTENSION SECTION W/
PARTIAL WALKABLE EXTENSION
AREA AND RAISED CURB RETURN
PEDESTRIAN
ACCESS ROUTE
(REPLACE AS
NECESSARY)
CURB EXTENSION
AMENITY ZONE
EXISTING
SIDEWALK
OR GROUND
CXS CXS
CXS
CXS VARIES
CXS VARIES CURB EXTENSION SECTION W/
SHALLOW ROAD CROSS SLOPE AND
WALKABLE EXTENSION AREA
VARIES
ACCESSIBLE CROSS SLOPE (CXS) = 0.5-1.0% (2% MAX)
CITY OF BOULDER STANDARD 6" CURB
AND GUTTER SEE DRAWING 2.01.A
REPAIR OR RECONSTRUCT
STREET PAVEMENT AS
NECESSARY
EXISTING CURB
AND GUTTER TO
BE REMOVED
EXISTING
ROADWAY TO
BE REMOVED
CITY OF BOULDER STANDARD 6" CURB
AND GUTTER SEE DRAWING 2.01.A
REPAIR OR RECONSTRUCT
STREET PAVEMENT AS
NECESSARY
EXISTING CURB
AND GUTTER TO
BE REMOVED
EXISTING
ROADWAY TO
BE REMOVED
CITY OF BOULDER STANDARD 6" CURB
AND GUTTER SEE DRAWING 2.01.A
REPAIR OR RECONSTRUCT
STREET PAVEMENT AS
NECESSARY
EXISTING CURB
AND GUTTER TO
BE REMOVED
EXISTING
ROADWAY TO
BE REMOVED
CITY OF BOULDER STANDARD 6"
CURB AND GUTTER SEE 2.01.A
REPAIR OR RECONSTRUCT
STREET PAVEMENT AS
NECESSARY
EXISTING CURB AND
GUTTER TO BE REMOVED
EXISTING
ROADWAY TO
BE REMOVED
DRAINAGE VALLEY
FLOW LINE. INCLUDE
DRAINAGE OUTLET OR
ENSURE POSITIVE
FLOW TO STREET
DRAINAGE FLOW LINE. INCLUDE
DRAINAGE OUTLET OR ENSURE
POSITIVE FLOW TO STREET
NON-WALKABLE AREA
WARNING CURB
NOTES:
1. MAY BE APPLIED TO BOTH
SHALLOW AND STEEP ROAD
CROSS SLOPE SCENARIOS
2. LANDSCAPED AREA MAY BE
USED FOR STORMWATER
TREATMENT, WHICH MAY
REQUIRE ADDITONAL
TOPOGRAPHIC AND
UNDERGROUND UTILITY
SAWCUT
SAWCUT
SAWCUT
SAWCUT
SAWCUT
SAWCUT
SAWCUT
SAWCUT
09.12.22 TAB Agenda 6 DCS Transportation
Page 130 of 143
FAR SIDE BUS STOP WITH SIDEWALK ELEVATION BIKE LANE NO
STREET PARKING, AND EXCLUDING CORNER RAMPS
(NOT TO SCALE)
FAR SIDE FLOATING BUS STOP WITH STREET ELEVATION BIKE
LANE, STREET PARKING, AND INCLUDING CORNER RAMPS
(NOT TO SCALE)
90' MIN PER OPERATOR STANDARD
90' MIN PER OPERATOR STANDARD
30-40' MIN (STANDARD BUS)
40-60' MIN (ARTICULATED BUS)
30-40' MIN (STANDARD BUS)
40-60' MIN (ARTICULATED BUS)
TAPER, TYP.
SEE NOTE 12 **B*C*A*15' R, SEE
NOTE 2 **
15' R GAP FOR
DRAINAGE
BOARDING AND ALIGHTING AREA, SEE NOTE 3 **
BUS PAD, COORDINATE WITH OPERATOR
FACE OF CURB
BUS PAD, COORDINATE WITH
OPERATOR
BOARDING AND ALIGHTING
AREA, SEE NOTE 3 **GAP FOR
DRAINAGE
SUPPLEMENTAL
DRAIN INLET
RAMP UP TO
SIDEWALK
ELEVATION, TYP
SEE NOTE 9 **
STYLE 1B CURB RAMP
2' R, SEE NOTE 2 **
SIDEWALK5'MIN.NEAR SIDE FLOATING BUS STOP WITH SIDEWALK ELEVATION BIKE
LANE, NO STREET PARKING, AND INCLUDING CORNER RAMPS
(NOT TO SCALE)
30-40' MIN (STANDARD BUS)
40-60' MIN (ARTICULATED BUS)
BOARDING AND ALIGHTING AREA, SEE NOTE 3 **
BUS PAD, COORDINATE
WITH OPERATOR
FACE OF CURB
SUPPLEMENTAL DRAIN INLET
MAY BE REQUIRED DEPENDING
ON DRAINAGE STUDY
TAPER, TYP.
SEE NOTE 12**SEE NOTES 9 AND 16 **
GAP FOR DRAINAGE
RAMP UP TO
SIDEWALK
ELEVATION, TYP C*A*LEGEND:
RAILING
DIRECTIONAL INDICATOR
STRIP
YIELD LINE 12"x18" WITH 3"
TO 12" SEPARATION
10' MIN
SEE NOTES 9 AND 16 **
SIDEWALK
SIDEWALK
BUS FLAG PER OPERATOR STANDARDS
BUS FLAG PER
OPERATOR STANDARDS
BUS FLAG PER OPERATOR
STANDARDS
= SECTIONS ARE FOUND ON DRAWING NO. X.XX.X
= NOTES ARE FOUND ON DRAWING NO. X.XX.X
15' R,
SEE NOTE 2 **
*
**
CUSTOM OM3-R
OBJECT MARKER
42" FLEXABLE
DELINEATOR
CUSTOM BIKE
ONLY SIGN R3-17
CUSTOM OM3-R
OBJECT MARKER
42" FLEXABLE
DELINEATOR
CUSTOM BIKE
ONLY SIGN R3-17
CUSTOM OM3-R
OBJECT MARKER
42" FLEXABLE
DELINEATOR
CUSTOM BIKE
ONLY SIGN R3-17
R1-5A
(OPTIONAL)
R1-5A
(OPTIONAL)
R1-5A (OPTIONAL)
09.12.22 TAB Agenda 6 DCS Transportation
Page 131 of 143
C.FLOATING BUS STOP
WITH BIKE LANE AT
SIDEWALK ELEVATION
B.FLOATING BUS STOP
WITH BIKE LANE AT
ROADWAY ELEVATION
** = NOTES ARE FOUND ON DRAWING NO. X.XX.X
BIKE LANE
RMP CXS
CXS
CXS
RNG
RNG
A.PEDESTRIAN CROSSING
OVER BIKE LANE WITH
PEDESTRIAN REFUGE
ISLAND IN FLOATING
BUS STOP
FLOATING BUS
STOPSIDEWALK
CITY OF BOULDER STANDARD CURB
AND GUTTER SEE DRAWING NO. 2.01.A,
SEE NOTES 13 & 15 **
BUS PAD
CITY OF BOULDER STANDARD CURB
AND GUTTER SEE DRAWING NO. 2.01.A,
SEE NOTES 13 & 15 **
BUS PAD
FLUSH CURB
REPAIR OR RECONSTRUCT STREET
PAVEMENT AS NECESSARY
OPTIONAL HANDRAIL,
SEE NOTE 16 **
EXISTING CURB AND GUTTER
AND ROADWAY TO BE
REMOVED
EXISTING CURB AND
GUTTER MAINTAINED
EXISTING ROADWAY
TO BE REMOVED
EXISTING CURB AND
GUTTER AND ROADWAY
TO BE REMOVED
CHAMFERED CURB,
SEE NOTE 13 & 15 **
FLUSH CURBFLUSH CURB
FLUSH CURB
NON-WALKABLE
AREA
EXISTING ROADWAY
MAINTAINED
OPTIONAL HANDRAIL,
SEE NOTE 16 **
LANDSCAPED
AREA
DIRECTIONAL
INDICATOR
FLUSH CURB
TREATMENT TO
CHANNELIZE
PEDESTRIANS TO
CROSSING, SEE
OPTIONS BELOW
ROADWAY
8' TO 10'
SEE NOTE 3 **
SAWCUT
SAWCUT
ACCESSIBLE RAMP SLOPE (RMP) = 7.8% (8.3% MAX)
ACCESSIBLE CROSS SLOPE (CXS) = 0.5-1.5% (2% MAX)
ACCESSIBLE RUNNING SLOPE (RNG) = 5% MAX
09.12.22 TAB Agenda 6 DCS Transportation
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NOTES:
1. DESIGN PLANS SHOULD BE CONSULTED FOR VARIATIONS.
2. NOSE OF FLOATING BUS STOP CAN BE DESIGNED AS MOUNTABLE TRUCK APRON, IF NECESSARY TO ACCOMMODATE
LARGE VEHICLE TURNING MOVEMENTS.
3. A MINIMUM 5-FOOT WIDE BY 8-FOOT DEEP BOARDING AND ALIGHTING AREA, WITH A MAXIMUM SLOPE OF 2% IN ANY
DIRECTION, IS REQUIRED AT FORWARD LOADING AREA ADJACENT TO THE BUS DOOR. THE 8-FOOT DEPTH MAY INCLUDE
THE ADJACENT CURBLINE, BUT IS EXCLUSIVE OF ANY RAILING OR CHAMFERED CURB SPACE. A 4-FOOT MINIMUM CLEAR
ACCESSIBLE ROUTE MUST BE PROVIDED BETWEEN THE BOARDING AND ALIGHTING AREA AND THE SIDEWALK. AN
ACCESSIBLE ROUTE MUST ALSO BE PROVIDED BETWEEN ANY PROVIDED BUS SHELTERS AND THE BOARDING AND
ALIGHTING AREA. IF A FLOATING BUS STOP SERVES MULTIPLE TRANSIT VEHICLE STOPS SIMULTANEOUSLY, BOARDING
AND ALIGHTING AREAS MUST BE PROVIDED AT EACH VEHICLE DOOR AND ACCESSIBLE ROUTES PROVIDED
ACCORDINGLY.
4. THE PREFERABLE FLOATING BUS STOP LENGTH IS BASED ON THE LENGTH OF THE BUS(ES) EXPECTED TO USE THE BUS
STOP. IF MULTIPLE BUSES ARE EXPECTED TO USE THE STOP AT THE SAME TIME, THE LENGTH SHOULD BE BASED ON
THE BUS LENGTH(S) WITH 20-FEET OF SEPARATION BETWEEN THE BUSES. THE LENGTH OF A FLOATING BUS STOP IS
EXCLUSIVE OF ALL PEDESTRIAN RAMPS.
5. LENGTH OF SIDEWALK REPLACEMENT WILL VARY BASED THE WIDTH OF THE FLOATING BUS STOP, EXISTING ROADWAY
CROSS SLOPES, CURB REVEAL, AND THE SLOPE AND GRADE OF EXISTING SIDEWALKS.
6. PEDESTRIAN CROSSINGS FROM THE SIDEWALK TO THE FLOATING BUS STOP MAY BE PROVIDED AT INTERSECTIONS, AT
LOCATIONS SEPARATE FROM THE INTERSECTION, AND/OR AT THE ENDS FURTHEST FROM INTERSECTIONS. TWO
PEDESTRIAN CROSSINGS ARE PREFERABLE BASED ON NATURAL PEDESTRIAN DESIRE LINES.
7. WHERE POSITIVE DRAINAGE CANNOT BE ACHIEVED ALONG CURBLINES, INSTALL NEW STORM DRAIN STRUCTURES AND
CONNECT TO EXISTING STORMWATER CONVEYANCE SYSTEM.
8. THIS NOTE INTENTIONALLY LEFT BLANK.
9. THE USE OF DIRECTIONAL INDICATOR STRIPS MAY ONLY BE CONSIDERED WHERE THE USE OF AN UNWALKABLE,
VEGETATED AREA, OR HANDRAIL BETWEEN THE BIKE LANE AND SIDEWALK WOULD RESULT IN A SIDEWALK WIDTH OF
LESS THAN 5-FEET, OR IS OTHERWISE NOT PREFERRED.
10. A MINIMUM 12-FOOT x 4-FOOT CLEAR SPACE, WITH A MAXIMUM SLOPE OF 2% IN ANY DIRECTION IS RECOMMENDED AT
ALL REAR BUS DOORS. IF THE REAR DOOR SERVES AS THE WHEELCHAIR ACCESSIBLE LOADING DOOR, A 5-FOOT X
8-FOOT LOADING AREA IS REQUIRED.
11. SEE CITY OF BOULDER DESIGN AND CONSTRUCTION STANDARDS, SECTION 2.07, TABLE 2.5 FOR STANDARD LANE
WIDTHS
12. BIKE LANE TAPERS PREFERRED AT 7:1 SHIFT, MINIMUM 3:1 SHIFT IN CONSTRAINED LOCATIONS WHERE SPEED IS ≤ 13
MPH
13. STANDARD 6 INCH CURB HEIGHTS ARE PREFERRED AND MAY REQUIRE PARTIAL OR FULL ROADWAY REGRADING. CURB
HEIGHTS OF 4 INCHES OR LESS MAY BE USED TO ACHIEVE POSITIVE DRAINAGE WITHOUT ROADWAY REGRADING. THE
USE OF CURB HEIGHTS BELOW 4" REQUIRES THE APPROVAL BY ENGINEER.
14. SLOPE TO REMAIN TRAVERSABLE AND DRAIN TOWARDS THE GUTTER. SLOPES NOT TO EXCEED 2%.
15. OVERALL CURB HEIGHT WILL VARY BASED ON EXISTING GRADES, CURB REVEALS, AND OPPORTUNITIES TO ADJUST THE
CURBLINE ELEVATION AT THE EDGE OF ROAD. ENSURE THAT THE CURB DEPTH EXTENDS AT LEAST 8 INCHES BELOW
FINISHED GRADE. FOR CURB REVEAL HEIGHTS THAT EXCEED 9 INCHES, DESIGN CURB AS AN ISOLATED REINFORCED
CONCRETE RETAINING CURB.
16. A HANDRAIL IS REQUIRED IF THE CURB HEIGHT EXCEEDS 8 INCHES. A HANDRAIL SHOULD BE CONSIDERED FOR ANY
CURB REVEAL OR ADJACENT TO SIDEWALK LEVEL BIKE LANES TO CHANNELIZE PEDESTRIANS TO THE CROSSWALKS.
ALTERNATIVELY, A NON-WALKABLE AREA OR DIRECTIONAL INDICATOR STRIP MAY BE CONSIDERED.
17. ADJUSTMENTS TO THE BIKE LANE ELEVATION MAY BE NECESSARY IF ROADWAY CROSS SLOPES EXCEED 2%. IF
ADJUSTING GRADE, ENSURE THAT POSITIVE DRAINAGE IS MAINTAINED ALONG THE CURB LINE OR PROVIDE ADDITIONAL
DRAINAGE STRUCTURES.
18. VALLEYS CREATED FROM REVERSE SLOPES SHALL BE DRAINED BACK TO THE CURB WHEN POSSIBLE TO AVOID PONDING
ON THE FLOATING BUS STOP. TRENCH DRAINS WITH ADA COMPLIANT GRATES ARE ALSO APPROPRIATE.
19. LIGHTING SHOULD BE PLACED TO ILLUMINATE ENTIRE FLOATING BUS STOP LOADING AREA.
20. WHERE PARKING IS PROVIDED ALONG THE STREET, FOLLOW RTD STANDARDS FOR TAPER LENGTHS APPROACHING AND
DEPARTING BUS STOPS.
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4' MIN. - SIDEWALKS
4' MIN. - BACK OF CURB
2' MIN. - SIDEWALKS
2' MIN. - BACK OF CURB
MEDIUM/LARGE TREE
SMALL/ORNAMENTAL TREE
NOTES:
1. REFER TO CITY OF BOULDER'S APPROVED TREE LIST
FOR ACCEPTABLE SPECIES FOR PLANTING WITHIN
PUBLIC R.O.W. CONIFEROUS TREES SHALL NOT BE
PLANTED IN THE PUBLIC R.O.W.
2. TREE SPECIES SHALL BE SELECTED TO ENSURE
MINIMUM VERTICAL CLEAR SPACE OF 7' CAN BE
MAINTAINED WITHIN SIDEWALKS. IN CONSTRAINED
URBAN SETTINGS, SPECIES SHALL BE SELECTED TO
ENSURE ADEQUATE PEDESTRIAN SPACE.
3. SEE DETAIL XX.X FOR TREE PLACEMENT AT
INTERSECTIONS AND TYPICAL TREE SPACING
7' MIN.7' MIN.U
6' MIN.
SIGNS
10' MIN.
UNDERGROUND
UTILITIES
10' MIN.
FIRE HYDRANTS
20' MIN.
STREET LIGHTS
TREE PLANTING BUFFERS
09.12.22 TAB Agenda 6 DCS Transportation
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NOTES:
1. ADDITIONAL SOIL VOLUME AREAS ARE
ENCOURAGED TO OBTAIN MINIMUM
SOIL VOLUME AND ENSURE LONG
TERM TREE VIABILITY. UTILIZE
STRUCTURAL CELLS, SOIL TRENCHES,
OR OTHER UNCOMPACTED SOIL
TECHNIQUES TO PROVIDE MAXIMUM
SOIL VOLUME BENEATH PAVED
SIDEWALKS AND PLAZAS.
2. RECOMMENDED SOIL VOLUMES:
A. SMALL/ORNAMENTAL TREES - 600 CF
B. MEDIUM TREES - 900 CF
C. LARGE TREES - 1,200 CF
3. SEE DETAIL X.XX FOR TREE SPACING
AND PLACEMENT REQUIREMENTS
NEENAH FOUNDRY TREE
GRATE R-8815-B
18" MIN.
OPENING
MINIMUM GRATE OR WELL AREA
SMALL/ORNAMENTAL TREES: 20 SF
MEDIUM TREES: 32 SF
LARGE TREES: 40 SF
X1
2 X 1
2 X
2X ROOT BALL
DIAMETER
OPTIONAL TREE GRATE
NEENAH R-8815-B
MULCH OR CRUSHER
FINES - 3" MIN.
AMENDED SOIL
UNDISTURBED
SUBGRADE
ROOT BALL
4' MIN.
COMPACT BASE
MATERIAL
SOIL VOLUME
AREA, SEE
NOTE 1
OPTIONAL TREE GUARD
NEENAH TYPE A, 5' TALL
18" MIN.
OPENING
09.12.22 TAB Agenda 6 DCS Transportation
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