SR 99 tunnel to close in both directions in Seattle for maintenance Sept. 5

Seattle's State Route 99 tunnel will undergo maintenance, closing in both directions from 10 p. m. on September 5 to 6 a. m. on September 6.

The Washington State Department of Transportation will start closing the northbound and southbound lanes at 8:30 p. m. , with the tunnel fully closed by 10 p. m. Drivers traveling south will need to exit at the Harrison Street off-ramp, while northbound drivers must exit at Alaskan Way.

The Sixth Avenue and Royal Brougham Way on-ramps will also close at 9 p. m. Maintenance work will include fire suppression testing, cleaning and marking drains, and fixing lights. The closure is expected to affect traffic flow in downtown Seattle, prompting officials to advise travelers to use alternate routes. For real-time traffic updates, users can access the WSDOT mobile app and travel map.

This maintenance is crucial for ensuring safety and functionality of the tunnel infrastructure.