Information from Washington State Department of Transportation
Two lanes of the northbound State Route 99 First Avenue South bridge over the Duwamish River are closed until further notice following a bridge inspection on Wednesday, Feb. 18, that identified concerns with the steel grid deck.
In addition to the lane closures, out of an abundance of caution, the Washington State Department of Transportation Wednesday night reduced the speed on the bridge to 25 mph to limit additional stress on the deck. The HOV lane is open to all traffic until further notice to help with traffic flow, and traffic can exit at Michigan Street.
The bridge remains open and operational, including for maritime traffic. Vessel openings will continue as needed.
Bridge engineers are on site again Thursday, Feb. 19, conducting a more detailed assessment. It is too early to outline a repair plan or timeline. WSDOT expects to have a preliminary report and provide updates to the public as repair plans are developed. The public can expect an update by Friday, March. 6.
Traveler expectations
People traveling through the area should plan for ongoing delays. Travel times will be longer and less predictable, particularly during peak travel times.
This comes on top of existing lane reductions on northbound I-5 as part of the Revive I-5 program to preserve the Ship Canal Bridge. Together, these conditions will place additional pressure on the regional transportation system.
Travelers are encouraged to plan ahead, allow for extra time, consider alternate routes and use WSDOT’s mobile app and real-time travel map for current conditions.
WSDOT continues coordination with the Seattle Department of Transportation and transit partners to monitor conditions and manage impacts where possible.
Bridge background
The First Avenue South Bridge is a movable double-leaf bascule bridge with two sections that lift from the center to allow marine traffic to pass along the Duwamish River. The northbound span was originally built in 1956 and rebuilt in 1998 and carries approximately 48,000 vehicles per day.
During its last inspection in 2024, the bridge was rated in fair condition. Like many structures across the system, this bridge requires ongoing maintenance and targeted maintenance repairs. In 2020, WSDOT undertook a select panel replacement project to replace 14 select deck panels. This lane reduction highlights the critical need for investment in preservation of our transportation system. Governor Ferguson proposed a $2.1 billion investment in preservation including $1.1 billion for bridges.
