Project overview
On Feb. 18, 2026, Washington State Department of Transportation bridge inspectors identified cracks in the steel deck grates on the northbound State Route 99 First Avenue South bridge in Seattle, requiring two lanes to close. Crews completed temporary repairs in early March to restore the original four-lane traffic pattern. In May, contractor crews replaced nine steel grate panels on the bridge deck most in need of repairs.
What to expect
Phase 1: Stabilizing the bridge (Completed March 9-13)
This work was completed on Friday, March 13, and all lanes of northbound SR 99 reopened across the First Avenue South Bridge at a temporary 25-mph speed limit.
Phase 2: Replacing nine failing panels (Completed May 8-11 and May 15-18)
Contractor crews replaced nine failing panels with 10 new steel grid deck panels during consecutive weekend closures May 2026. Intermittent overnight lane closures are possible in the coming weeks for striping and final "punch list" items to finalize the project.
Phase 3: Long term preservation work (2027)
Design work is underway for a full replacement of nearly 75 remaining steel grid panels on the northbound SR 99 bridge deck, with construction expected to start in 2027. This project will address broader needs and will require more substantial coordination with the U.S. Coast Guard and regional partners. More information will be shared on this phase of the project in early 2027.
The SR 99 First Avenue South bridge in Seattle crosses the Duwamish River near Boeing Field.
The First Avenue South bridge is a moveable, double-leaf bascule bridge spanning the Duwamish River. Like a drawbridge, its two sections lift from the center to allow marine traffic to pass. When closed, the two halves meet to carry vehicles, transit and freight.
Because the bridge both moves and carries heavy daily traffic, it includes mechanical systems and specialized steel deck components that require ongoing maintenance and inspection. Areas near the center of the span experience the greatest stress. During its last full inspection, the bridge was rated in fair condition.
The First Avenue South bridge is part of a statewide bridge system with infrastructure operating beyond its intended service life. WSDOT often extends the life of these bridges through targeted repairs while larger preservation projects are being developed. That approach allows structures to remain in service, but it also means that when conditions change, crews must act quickly and sometimes close lanes or structures in the interest of public safety. Each time WSDOT must take this action highlights the critical need for investment in the preservation of our transportation system. Governor Ferguson proposed a $2.1 billion investment in preservation including $1.1 billion for bridges.
