The State Route 99 tunnel in Seattle will undergo maintenance, resulting in a complete closure in both directions from 10 p. m. on February 21 to 6 a. m. on February 22.

The Washington State Department of Transportation (WSDOT) will begin closing the northbound and southbound lanes at 9 p. m. to facilitate this work. Drivers traveling south must exit at Harrison Street, while those heading north should use the Alaskan Way off-ramp. The Sixth Avenue and Royal Brougham Way on-ramps will also be closed at 9 p.

m. During this closure, crews will perform important maintenance tasks, including fire suppression testing, drain cleaning, and light repairs. People traveling through downtown Seattle are advised to plan alternate routes to avoid delays. For the latest traffic information, the WSDOT mobile app and real-time travel map are recommended resources. This maintenance is essential for ensuring the safety and functionality of the tunnel for all users.