Two northbound lanes on the busy First Avenue South bridge in Seattle are closed for at least several weeks. The closure follows the discovery of damage to the bridge’s steel open-grid deck during a routine inspection. The bridge over the Duwamish River is part of the critical Highway 99, and the closure will significantly affect regional traffic. Officials have not yet disclosed all details about the nature of the defects.
Engineers found issues both in deck sections that were replaced as recently as six years ago, in 2020, and in older parts of the bridge that date back to its 1956 construction. A Washington State Department of Transportation (WSDOT) spokesperson noted that a typical quick fix using steel patches is not suitable in this case because their weight could damage the movable mechanisms of the drawbridge. The team is looking for an alternative solution and hopes to present a repair plan by March 6.
Until repairs begin, northbound traffic on the bridge is routed into the two remaining left lanes with a speed limit reduced to 25 mph. The high-occupancy vehicle lane has been temporarily opened to all traffic. About 48,000 vehicles use this route daily, and the lane reduction is likely to cause significant congestion. The situation is worsened by concurrent repair work on another key I-5 bridge in the northern part of the city.
Based on: Two Highway 99 bridge lanes close for weeks; damage found in steel deck