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From Tech Transfer Newsletter, Winter 2006
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Roundabouts Case Study:
Bird Rock Traffic Management Plan
By Siavash Pazargadi, P.E., Senior Traffic Engineer
City of San Diego Planning Department
The Bird Rock Neighborhood
The Bird Rock neighborhood is located south of La Jolla, California in the city
of San Diego. It has a population of about 16,000. It is a coastal community,
comprised of a set of commercial and mixed use developments along its major
roadway, La Jolla Boulevard, which is also the primary route for vehicular
access to La Jolla from the south. La Jolla Boulevard is connected to a network
of residential and collector streets in the Bird Rock area.
The Bird Rock Traffic Management Plan was created to address the concerns of
area residents and businesses. Their concerns included the high speed of traffic
and the wide width of La Jolla Boulevard, difficult pedestrian crossing,
cut-through traffic, speeding on area residential streets, peak hour congestion
at a local elementary school, and the aesthetic condition and financial
stagnation of businesses in the area.
The Bird Rock Traffic Management Plan
The resulting comprehensive plan includes all of the Bird Rock area streets and
intersections. The five modern roundabouts where La Jolla Boulevard intersects
with five collector streets are the main feature of the project.
The roundabouts on La Jolla Boulevard would reduce the number of traffic lanes
from four to two (i.e., one in each direction). This reduces the crossing
distance for pedestrians on La Jolla Boulevard substantially, which would result
in less pedestrian exposure to vehicular traffic and thus a potential reduction
in pedestrian accidents.
The roundabouts, through design, also reduce traffic speed to about 15-20 MPH.
This would improve safety as the severity of accidents would be reduced due to a
reduction in speed. The reduction in traffic lanes also makes additional space
available, allowing for intersection and median beautification including
landscaped center medians.
In addition, the plan includes a mini-roundabout at another intersection and
four traffic circles on the residential streets that would also help in speed
reduction and safety improvement. The plan further includes 25 traffic calming
measures such as bulb-outs (or extension of sidewalks that reduces the
pedestrian crossing distance), a speed lump (using a new split-hump design) to
reduce speeding, raised center medians, and street marking.
In addition, the project includes construction of new sidewalks and provides 30
additional parking spaces along La Jolla Boulevard with diagonal parking in a
five block area. The project also includes installation of a new Class II bike
lane that provides better accessibility for bicycles, so that bicyclists do not
have to use La Jolla Boulevard with its new diagonal on-street parking in the
project area. The plan further includes relocation and reconfiguration of bus
stops, and new bus pads and bus benches.
The first phase of the project includes two roundabouts that have already been
constructed. They are a development requirement for an adjacent condo project.
The other three roundabouts and the rest of the residential traffic calming
measures are to be constructed in Phase II, by the city in 2007.
Accommodating Pedestrians with Impaired Vision
Several design improvements have been incorporated to better accommodate
pedestrians who are blind crossing at roundabouts, including: construction of
new intersection crossings at about two vehicle lengths behind the roundabout
yield line, installation of rumble strips at exit and tangential approaches to
crosswalks, planting of low profile shrubs around the circles all the way to the
crosswalks, and construction of in-pavement flashers on La Jolla Boulevard.
Bird Rock Area Revitalization
Landscaped roundabouts and medians together with the new diagonal parking spaces
would create a village atmosphere that promotes walking and better accommodates
outdoor activities. The project has helped revitalize La Jolla Boulevard, which
was suffering from a financial stagnation by area businesses. The project has
been a catalyst to a number of smart growth type developments along La Jolla
Boulevard including a 139-unit condominium development, several new mixed use
developments, and a major drugstore.
See for Yourself
Watch for the National LTAP sponsored Product Demonstration Showcase featuring
the Bird Rock Neighborhood series of roundabouts, coming in spring 2007.
Information about the showcase will be available at
http://t2.ce.ufl.edu/pds/ as the showcase date approaches.
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