People who use State Route 99 in Seattle will want to plan for a full closure of the tunnel Friday night, June 7, to Saturday morning, June 8.
Washington State Department of Transportation maintenance crews will close both directions of the SR 99 tunnel from 10 p.m. Friday, June 7, to 8 a.m. Saturday, June 8, for maintenance work and updates to the fire control system software. This work will temporarily deactivate the fire control system, which is why crews need to close both directions of the tunnel.
Similar to previous maintenance closures, crews will also inspect the jet fans, cameras and overhead signs as well as sweep the roadway. The monthly maintenance closures allow crews time to assess the tunnel systems and keep up with the warranties.
Regular monthly maintenance closures of the tunnel usually close just one direction of the tunnel. In July, crews will resume the regular schedule and close the northbound lanes.
Travelers who use the tunnel should plan alternate routes during the closure. Before heading out the door, check the latest road closures on the WSDOT app and by following the WSDOT Traffic Twitter feed.