05.09.22 TAB Agenda 6 - DCS Transportation StandardsCITY OF BOULDER
TRANSPORTATION ADVISORY BOARD
AGENDA ITEM
MEETING DATE: May 9, 2022
AGENDA TITLE:
Transportation Standards Update (Phase 2) Briefing and TAB Feedback
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 status update on Phase 2 of the transportation 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 in February 2020. The Phase 2 DCS update will focus on Street Geometric Design and
Streetscape/Landscaping Design and Maintenance and will also include an update to the Sight Triangle
portion 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 team has developed initial “60%-level” recommendations for changes and is
collecting input on these from the community and from boards in April-May 2022 with anticipated
adoption of final updates to the documents in Q3 2022.
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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 sections of the DCS are anticipated in future years.
The goals of the Phase 2 update are to:
- Overall: Modernize the requirements to which facilities are designed and constructed so private
and public projects are consistent and uniform in application. This aligns with the departments’
Operational Excellence guidepost and being more efficient 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 with
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
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. The team presented to CCAC and to the Center for People with Disabilities and also
held three separate virtual office hours. Highlights of the initial (60%) recommendations, as well as
working drafts of Chapters 2, 3, and 10 are posted on the project website for input through May 1. Some
of the key themes of input received to date include:
- Support for the proposed changes related to:
o Narrower lane widths to slow vehicle traffic
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o Minimizing the number of left turn lanes to minimize crossing distances
- Support for additional raised crossing details (note: this is currently in progress and will be part
of the 90% level recommendations)
- 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
- Reminder to build facilities that we can maintain
- Concern about excessive signage and markings
- Concern about pedestrians and people with disabilities being able to safely and easily navigate
traffic circles
In addition to this update (May 2022), TAB received a briefing in September 2021. The August 2022
TAB meeting will include a public hearing and TAB will be asked to make a recommendation to
Planning Board and City Council regarding the proposed updates. Planning Board will receive a briefing
in May 2022 and will have a public hearing and be asked for a recommendation to City Council in
August 2022. The project is scheduled to be presented to City Council for approval in September 2022.
PROJECT SCOPE:
The scope of the Phase 2 update is focused on street geometric design and streetscape design and
standards, as detailed below.
Street Geometric Design
The intent of the update to the Street Geometric Design (Section 2.07) is to consider 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 will soon start design. 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
(E) Vertical Alignment
(F) Sight Distance—UPDATED
(G) Medians
(H) Vertical Clearance of Structures
Tables:
Table 2-5: Minimum Street Lane Widths—
UPDATED
Table 2-6: Minimum Horizontal Street Curve
Specifications
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
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(SU-30)—NEW
Table 2-9: Maximum Street Grades
Table 2-10: Vertical Curve Design Control
Table 2-11: 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
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.
Add statement that 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 update within Chapter 2 is Street Geometric Design (Section 2.07), for
consistency and completeness, other related and incidental updates are also being proposed. For
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example, the project team wanted to ensure that the new bike lane widths in Table 2-5 and other related
details were 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 for now (Section 2.14 –
Traffic Calming); the team is still determining the best way to integrate this information in the final
document.
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 Reconstructed 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 figures
Figure 10 – Typical Layout and Standard Dimensions of Neighborhood
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 figure
Figure 11 - Typical Layout of Raised Crossing at Mid-Block Location—
NEW
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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 use to reflect the Transportation Landscapes Plan
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
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
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o 2.07.O Floating Bus Stop Detail – Intersection Far Side
o 2.07.P Floating Bus Stop Cross Sections – Intersection Far Side
- Related to Section 2.14:
o 2.14.A Midblock Raised Pedestrian Crossing (from Ch. 2 Fig 11)
- Related to Chapter 3:
o Streetscape Tree Spacing and Location – Offset Drawing
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
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.
For additional details and links to figures and drawings, as well as full working draft documents, please
visit the project website.
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Timeline
The project is expected to extend through Q3 2022, returning to TAB and Planning Board for
recommendation to City Council in August and a City Council hearing for approval in September.
NEXT STEPS:
Next steps include continuing to gather input from the community and refining the initial
recommendations into draft final (90%) recommendations.
At the August 2022 TAB meeting the draft final (90%) recommendations will be presented; this meeting
will be a public hearing, and TAB will be invited to make a recommendation to Planning Board and City
Council.
QUESTIONS FOR TAB:
1. What questions do you have about the community engagement?
2. What suggestions do you have to enhance the proposed changes?
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