SR 99 tunnel to close in both directions in Seattle for maintenance Sept. 5
The Washington State Department of Transportation will close the SR 99 tunnel in Seattle for maintenance on September 5, starting at 8:30 p. m. and achieving full closure by 10 p. m. Southbound drivers must exit at Harrison Street, while northbound drivers should take the Alaskan Way exit.
The Sixth Avenue and Royal Brougham Way on-ramps will also close at 9 p. m. Maintenance activities will involve fire suppression testing, cleaning drains, and repairing lights. This closure is essential for ensuring safety and functionality in the tunnel. Travelers in downtown Seattle that night should use alternate routes to avoid delays.
For the latest traffic updates, the public is encouraged to use the WSDOT mobile app.