Non-Agenda Item - Memorandum re: City of Boulder Arterial Count Program (2001)
MEMORANDUM
TO: Members of the Transportation Advisory Board
Members of the Planning Board
Tracy Winfree
Michael J. Gardner-Sweeney t
Joe Paulson
Bob Major
Michelle Coffelt
Nataly Handlos
Micki Kaplan
Marni Ratzel
Andrea Robbins
Randall Rutsch
Bob Whitson
Noreen Walsh
Joan Salas
Steve Durian
Commander Tom Wickman, Boulder PD - Traffic
Bill Fox, Fox Higgins Transportation Group t
Steve Tuttle, Transplan Associates Inc. t
Jim Charlier, Charlier Associates Inc. t
Larry Haas, Colorado Department of Transportation t
Mike Thomas, Boulder County Transportation t
FROM: Bill Cowern, Transportation Operations Engineer
DATE: April, 19, 2002
SUBJECT: FYI - City of Boulder Arterial Count Program (2001)
The City of Boulder has been collecting traffic count data on the arterial street system since 1982. A set
of 27 count stations has been consistently counted since 1989. Traffic volumes on these streets have
increased, with yearly growth rate increases of between 0 percent and five percent this year.
Transportation staff has been following the growth trends on these roadways in an attempt to track
progress on Transportation Master Plan (TMP) objectives established in 1996. In 2001, staff began
implementing a new arterial count program system, which counts our major arterial streets along
significant east-west and north-south screen lines. The transition in program strategies resulted in the
2001 program only counting 17 of the original 27 locations. Continuity of the historical data trends has
been influenced by this change. The program will be incrementally expanded from the current 17 count
stations to an ultimate program of 57 fully automated count stations.
Since the adoption of the TMP update in 1996, staff has observed a marked decrease in the traffic growth
rate along these arterial roadways. Traffic is still growing but the rate at which it is growing is
significantly lower than in prior years. This slowdown in traffic growth is significant as it suggested that
TMP strategies may be effective at containing traffic growth. The goal of the City of Boulder's TMP
update was to maintain traffic at 1994 levels. Since 1994, traffic volumes have increased and decreased
on different roadways, but on the whole have stayed very close to 1994 levels. This consistent level of
traffic suggested a trend of slowing traffic growth. Such a trend, sustained over time, might result in an
eventual decrease in traffic.
However, last year (2000) and this year (2001), the Arterial Count Program has shown more significant
increases in traffic volumes throughout the system. In 2000 traffic grew by approximately 1.6 percent.
In 2001, there was a further 4.8 percent increase in the seventeen count stations studied. Since 1994, the
amount of traffic on our arterial roadways grew by approximately 8 percent or an average of 1.1 percent
annually. Future year data will be required to determine if the new trend indicated by 2000 and 2001 data
is sustained.
One of the ways that staff evaluates the historical significance of traffic count data is to examine the
trends of the five-year growth rate. This value is the rate of growth over. any five-year period in the
program. It is useful to track whether the five year growth rate increases or decreases with each passing
year, to see whether trends over a period of time are positive or negative. In 2000, the five-year growth
rate increased for the first time in five years (rising from 0.06 percent per year to 0.63 percent per year).
In 2001, the five-year growth rate increased again (rising from 0.63 percent per year to 1.82 percent per
year).
Another factor considered is a linear regression analysis of the total count program traffic (see attached
table and graph). The results of these analyses indicate that the rate of traffic growth throughout the
history of the arterial count program continues to decrease. In 1996, 1997, 1998, 1999, and 2000, the
linear regression growth rate was approximately 2.5, 2.3, 2.2, 2.1 and 2.0 percent per year, respectively.
In 2001, the linear regression growth rate dropped to 1.8 percent. Projected out, this would imply
approximately 29 percent higher traffic volume/demand at Year 2020. The 'curve-fit' criteria indicate
correlation in the data of plus/minus 8.2 percent.
Boulder Valley Count Program Comparison
The City also performs what is called the "Boulder Valley Count Program" on a yearly basis. This
program counts traffic at the 18 different locations that traffic enters or exits the City of Boulder. The
results of this program are documented separately. In summary, the 2001 program results showed that
traffic entering/exiting the City throughout the day is still increasing and the rate of growth has increased
to 2.9 percent per year (compared to an average growth rate of 2.8 percent per year the past two years).
Traffic entering/exiting the City of Boulder is increasing at a much faster rate than traffic growth internal
to the City.
If you have any comments or suggestions give me a call.
t - with attachments
* - vpd = vehicles per day