April 27, 2:06 PM click here to comment > 3
Protecting Seattle streets and neighborhoods from 520 bridge traffic
I’ve heard a lot of concerns from residents about the traffic impacts of the state’s project to build a new, six-lane SR 520 bridge. The basic issue is how to accommodate additional traffic on an already congested Interstate 5 and at the Montlake Cut. In addition, the state only has enough money right now to build a six-lane bridge from the Eastside to Foster Island, where it would merge down to four lanes.
We need good data that shows us what the traffic impacts will look like. But the Washington State Department of Transportation (WSDOT) hasn’t given us a clear picture of what may happen to Seattle neighborhoods. Their preliminary traffic analysis was based on an earlier version of the design. They could be engineering a traffic jam right next to the Arboretum and in Seattle’s neighborhoods.
We need to better understand and address the impacts of this megaproject. We’d like to work with the state to get some better data and have them commit to help fix traffic impacts, especially before the Final Environmental Impact Statement is finished later this year. Seattle Department of Transportation Director Peter Hahn wrote to Paula Hammond, head of WSDOT, with specific requests for new research and for mitigation of traffic impacts on neighborhood streets. City staff are ready to work with WSDOT to figure out exactly how to make this project work better for Seattle neighborhoods.
It’s important that we get this right. Now is the time to take a close look at the traffic impacts, before we’re too far along to correct course. The cost to taxpayers, to neighborhoods, and to our quality of life is too high to wait.
Peter Hahn’s letter is below – click here for a PDF version.
April 27, 2011
Paula Hammond, Secretary of Transportation
Washington State Department of Transportation
310 Maple Park Avenue SE
P.O. Box 47316
Olympia, WA 98504-7316
Dear Ms. Hammond:
As you know, the City of Seattle and the Seattle Department of Transportation (SDOT) continue to have major concerns with the State’s preferred alternative for the SR 520 bridge replacement and HOV project. Impacts to Seattle streets are chief among these concerns. If this project moves forward, we have a basic obligation to understand these impacts clearly and to ensure we are adequately addressing them. I hope this letter will begin a constructive dialogue with you and your staff and move towards further study and targeted solutions that address traffic impacts.
We have specific requests that I believe will lead us toward those solutions. In April 2010, SDOT submitted technical comments on the state’s Supplemental Draft Environmental Impact Statement (SDEIS). In that comment letter we requested “a fully-calibrated VISSIM-like model for Montlake Boulevard, Pacific Street, 23rd Ave., and Lake Washington Blvd.” The traffic modeling that we have reviewed to date is based on an earlier version of the corridor’s westside design. During the ESSB 6392 process, the design was changed, and we have not had the opportunity to review the updated traffic analysis for this new preferred alternative. Since the publication of the SDEIS, there have been design refinements that affect neighborhood traffic.
Prior to publication of the Final Environmental Impact Statement (FEIS), SDOT requests the two items outlined below.
1. Full study of the traffic impacts (i.e., traffic volumes, intersection LOS, and total intersection delay in seconds) on city arterials between Madison St in the south and 75th St in the north, and from Montlake Blvd west to I-5, undertaken by a third party. This study will include, at a minimum, the following:
a) VISSIM-like model of the city arterials
b) Traffic analysis for the new Preferred Alternative using 2010 traffic data
c) Sensitivity analysis of travel times under varying tolling assumptions
d) Sensitivity analysis of travel times for major construction periods
e) Traffic analysis for city arterials testing the network impacts due to bascule bridge openings in the hours immediately before and after the peak period
2. Once this study is done, we request a list of mitigation commitments by WSDOT for identified traffic impacts. Examples of appropriate mitigation elements could include:
a) A comprehensive intelligent transportation system (ITS) program for Montlake Boulevard and 23rd Avenue. Key features of this program should be dynamic message signs, signal system upgrades, emergency vehicle preemptions, and live travel time information.
b) A traffic management plan for Lake Washington Boulevard that includes traffic calming measures, improved pedestrian crossings, etc.
c) A transportation demand management program to reduce vehicle miles traveled (VMT) in an effort to meet the state mandated reduction targets.
d) Funding for transit on the corridor and on city streets.
e) Transit priority treatments, such as queue jumps and bus-only lanes, to help both local and regional transit in the project area.
SDOT staff is committed to working with your staff on these requests prior to publication of the FEIS. We look forward to making this project better for the city of Seattle and the region.
Peter Hahn, Director
Seattle Department of Transportation
Posted by: Mayor Mike McGinn