Drivers who use the southbound SR 99 Duwamish River Bridge – also known as the First Avenue South Bridge – should plan for overnight closures and lane reductions starting this Friday, March 5, 2021.

This is the first of four overnight closures during the two-week project. Contractor crews working for the Washington State Department of Transportation will repair bearing pads and steel beams that support the structure.

Southbound SR 99 bridge closures:

    • Friday, March 5 and Saturday, March 6: full closures from 9 p.m. to 6 a.m
    • Noon Wednesday, March 10 through noon Monday, March 15: Two lanes closed 24 hours a day.
    • Sunday, March 14 and Monday, March 15L: full closures from 9 p.m. to 5 a.m.

During this work, travelers should consider avoiding the bridge, particularly during peak travel hours. Alternative routes include East Marginal Way South Bridge, the Tukwila International Boulevard Bridge, Interstate 5 and the South Park Bridge.

The northbound SR 99 Duwamish River Bridge is not affected by this work.

Drivers can get real-time traffic information on mobile phones with the WSDOT traffic app and by following the WSDOT traffic Twitter feed.