City releases draft traffic study on Curtis Park Village
By Dan Murphy
Viewpoint Staff Writer
The January 2006 draft traffic study for the Curtis Park Village project
was released last month to SCNA by city staff. The draft is subject to
change before it becomes a part of the impending draft environmental impact
report (DEIR). However, it is likely the main features and much of the
information will be included in the DEIR.
The two-chapter, 112-page draft is daunting on first perusal, bristling
with dense tables, myriad intersection diagrams, and technical terminology.
It can be downloaded from the SCNA Web site at www.sierra2.org.
The foundation for analysis of the project's traffic effects is determining
how many additional vehicle trips the proposed 72-acre development of
residential and commercial uses will generate. The draft traffic study
concludes that the project will cause about 22,520 trips on an average
day. After discounts for public transit trips, internal trips, and commercial
trips that are only diversions from existing Sutterville Road traffic,
the study concludes that the number of new vehicle trips outside the project
boundaries will be 12,129. Of these, 605 would occur during the peak morning
commute hour and 1,233 during the peak evening commute hour.
The study then assigns these new vehicle trips to the existing road network.
"Existing" as used here means the present road network and the
approved changes that will soon be in effect, such as the Freeport Boulevard/21st
Street two-way conversion project. The study also examines the effect
of some alternative scenarios for access to and from the project, for
example, access at both Donner Way and Fifth Avenue. In brief, the draft
allocates roughly 75% of the commercial trips to the new entrance on Sutterville
Road and roughly 25% of the commercial and residential trips to the proposed
Donner Way/Fifth Avenue entrance(s). In addition to access alternatives,
the draft also considers some land use alternatives, principally alternatives
with smaller amounts of commercial use. All the alternatives are assessed
at present, under "existing" conditions, and, based on the regional
SACMET 2027 travel demand model, the projected conditions in 20 years.
Perhaps the most interesting premise of the draft's allocation of trips
is that virtually no traffic would exit the project through the new northwest
connection to Portola Way. The draft asserts without explanation that
left turns from the new Portola/21st Street entrance onto Fourth Avenue
and then to 21st Street must be prohibited. Thus, traffic exiting the
project for downtown during the morning commute would either use the Donner
Way/Fifth Avenue entrance(s) to 24th Street, or go south to Sutterville
Road.
The next step in the draft is to assess whether the new external vehicle
trips, when added to the existing traffic pattern, will have significant
impacts for purposes of the environmental impact report. The draft uses
three different yardsticks for identifying significant impacts. The first
is the effect of the project traffic at intersections, such as 24th Street
and Second Avenue, during peak morning and evening commute hours on the
level of service (LOS). Intersection LOS is a generally used measure of
congestion and delay experienced by motorists.
The second yardstick is the effect of the average daily traffic increase
on the LOS of road segments, for example, Donner Way east of 24th Street.
Road segment LOS is a locally defined measure of the ratio of actual volume
to a maximum daily traffic figure deemed acceptable under city design
guidelines. Again, this is based on operating conditions experienced by
motorists. The last yardstick is the effect of the project traffic on
freeway ramp backups, freeway ramp LOS, and freeway LOS. The standards
here are provided by CalTrans.
The draft identifies various significant impacts of the project or alternatives
both under existing conditions and in future years. Two identified impacts
of the project under present conditions are found to be unavoidable: project
traffic would cause significant deterioration of the LOS on segments of
Sutterville Road and add significant traffic to Highway 99 during the
peak evening hour. By 2027 there would be the following additional unavoidable
impacts: LOS deterioration at the Sutterville Road/ Curtis Drive intersection;
a deterioration of LOS on 24th Street between Portola and Marshall Ways
and on Freeport Boulevard north of Taylor's Market; and a backup exceeding
the length of the 12th Avenue off-ramp of Highway 99.
Many project-related traffic increases on neighborhood streets are deemed
insignificant by the draft. For example, traffic would increase by almost
half on 24th Street north of Donner Way and on Donner Way itself and Fifth
Avenue traffic would increase two-and-a-half or threefold. These increases
are deemed insignificant. One piece of good news is that traffic on 24th
Street south of Donner Way would decrease to about a sixth of the present
level.
The draft does not explain some important assumptions and choices made
in reaching its conclusions which could significantly affect its predictions.
There are a number of traffic figures presented which do not seem sensible
on a first reading. The SCNA Neighborhood Concerns Committee has begun
work on analyzing the draft and is looking into these and other questions
about the effect of the projected traffic on the neighborhood. SCNA will
hold neighborhood meetings to discuss traffic issues in the coming months.
Return
to Viewpoint Index
|