HomeMy WebLinkAboutTIC 2017-10-10 Item 2E - Discussion - Speed Cushion Pilot Project: Implementation CriteriaCity of Tukwila
Public Works Department - Bob Giberson, Director
TO: Transportation and Infrastructure Committee
FROM: Robin Tischmak, Acting Public Works Director
CC: Mayor Ekberg
DATE: October 6, 2017
SUBJECT: Speed Cushion Pilot Project - Implementation Criteria
Project No. 91610410
Allan Ekberg, Mayor
ISSUE
Develop implementation criteria for traffic calming features that include speed cushions and/or radar
speed display signs on residential streets in the event that funding is programmed in future budget
cycles.
BACKGROUND
The City's Capital Improvement Program (CIP) has historically included a Neighborhood Traffic
Calming Program that is unfunded due to staffing needs. A speed cushion pilot project was
implemented on S 160th St to determine the effectiveness of innovative speed cushions in conjunction
with radar speed display signs. Formal criteria are desired for the possible implementation of similar
improvements on other residential streets throughout the City in case funding is budgeted to expand
this effort into an ongoing program.
DISCUSSION
The three most common engineering criteria used to justify traffic calming initiatives are related to
speeding, traffic accidents and vehicle volumes. High speeds and a history of traffic accidents are
primary safety concerns. Vehicle volumes are an indicator of the type of roadway facility and would be
used to determine the cost effectiveness of installing improvements. Very low volume streets may not
merit the cost of traffic calming measures while higher volume streets (those arterials intended to move
traffic) may likely have the adverse consequence of causing cut -through traffic on adjacent streets. In
addition to the common criteria mentioned above, other factors can be evaluated for consideration such
as: population density, school routes, existing pedestrian facilities, transit routes, or other
characteristics specific to a street under consideration.
After evaluation, a determination to install radar speed display signs, speed cushions, or other traffic
calming measures will be made. Evaluations could include a determination of no action, installation of a
singular item, multiple items, or a progressive approach from radar speed display signs to speed
cushions.
FINANCIAL IMPACT
There is currently no financial impact as there are no funds budgeted for this program.
RECOMMENDATION
For information only.
W:\PW Eng1PROJECTSIA- RW & RS Projects\Traffic Calming1160th Speed Cushion Pilot Project\info memo TIC speed cushions.docx
6300 Building • 6300 Southcenter Boulevard Suite ioo • Tukwila, WA 98188 • 206-433-0279
Tukwila City Hall • 6200 Southcenter Boulevard • Tukwila, WA 98188 • 206-433-1800 • Website: TukwilaWA.gov
37