WA weekened travel alert: Major closures on I-405, SR 520 and SR 99 to cause delays

SEATTLE - Drivers across the Puget Sound region should prepare for significant travel delays this weekend as state transportation crews launch a series of major highway construction projects starting Friday, Aug. 21. 

What we know:

The Washington State Department of Transportation (WSDOT) announced multiple overlapping closures on Interstate 405, State Route 520, State Route 99 and Interstate 5. 

Officials warn that traffic shifts onto local streets and alternate routes will likely create heavy regional congestion. 

Keep reading to see details about each project:

Weekend road closures across Puget Sound

Work begins Friday night, Aug. 21, and spans several key transit corridors: 

• Southbound I-405 (Bellevue to Renton): Fully closed from Coal Creek Parkway Southeast to North 30th Street starting at 11:30 p.m. Friday through 4 a.m. Monday, Aug. 24. Associated ramp closures include the Coal Creek Parkway SE on-ramp, Exit 9 (Lake Washington Blvd), Exit 7 (NE 44th St), and the Exit 6 off-ramp. Crews will conduct drainage work, repaving, and a traffic switch.SR 520 / Montlake Boulevard Interchange: Montlake Boulevard will close between East Hamlin Street and East Louisa Street from 10 p.m. Friday to 6 a.m. Monday. Ramps to eastbound/westbound SR 520 will close, along with portions of East Roanoke Street and Lake Washington Boulevard. Crews are installing updated sign structures. Pedestrian and bicycle paths across SR 520 will remain accessible. 
• Northbound SR 99 (First Avenue South Bridge): Fully closed from 5 a.m. Saturday, Aug. 22, through 11:59 p.m. Sunday, Aug. 23, for bridge preservation work. Drivers cannot access East Marginal Way or Michigan Street from the bridge during this time. 
• Northbound I-5 (Ship Canal Bridge): Remains reduced to two lanes as part of the ongoing Revive I-5 project. Express lanes will remain open northbound 24 hours a day. 

Local perspective:

The concentration of work means travelers moving between Seattle, Bellevue and south King County will face bottlenecks on almost every primary route. Local arterials surrounding Bellevue, Renton, and Seattle's Montlake neighborhood are expected to absorb diverted freeway traffic, likely causing secondary delays on city streets.

What you can do:

Transportation officials are encouraging drivers to take steps to avoid getting stuck in traffic:

• Allow Extra Time: Expect trips to take considerably longer than usual.
• Use Transit: Consider public transit, Light Rail, or park-and-ride options to bypass freeway congestion.
• Check Conditions: Review the WSDOT mobile app or online Travel Center map prior to departure for real-time traffic updates.
• Drive Safely: Reduce speed, stay alert, and watch for work crews in active construction zones.

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