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

Project news

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Needs & benefits

The bearings 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 will repair deteriorating bridge bearings at these two piers until a permanent repair can be scheduled, likely in early 2021. This work will require multiple short closures of the bridge each day, similar to closures when the bridge needs to open for marine traffic.

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 make temporary repairs.
  • Fall 2020: Project will be advertised for competitive bidding.
  • January 2021: Permanent repairs begin.
  • Spring 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.