SR 99 - SR 509 Southbound Duwamish River Bridge - Bridge Repair

Project news

  • Lane closures are complete.
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Needs & benefits

The bearing pads on two piers that support the SR 99 southbound Duwamish River Bridge have some wear causing some settlement of the bridge deck on top of those piers. Our maintenance crews repaired deteriorating bridge bearings at these two piers until a permanent repair can begin. Permanent repairs by crews from Massana Construction Inc. will require up to four overnight full closures between 10 p.m. and 5 a.m. It will also require up to 15 days with the bridge reduced to two lanes 24 hours a day. The work does not affect the northbound bridge.

The bridge is safe for travel.

Making these repairs helps preserve the bridge, which is a vital link between Seattle and SeaTac, Burien and other south King County communities.


  • October 2020: WSDOT crews made temporary repairs.
  • January 2021: Project awarded to Massana Construction Inc.
  • March 5, 2021: Permanent repairs begin.
  • March 2021: Permanent repairs complete.


The cost estimate for this project is less than $1 million.


Tom Pearce
WSDOT communications

A small map showing the location of the SR 99 Duwamish River bridge

Repairs are planned for the SR 99 southbound Duwamish River Bridge.