4th Ave S Bridge Repair

Updated June 23, 2022

What's happening now?

We are finalizing the design for the repair of the 4th Ave S Bridge. We expect to finalize the design in 2022 and begin construction in 2023.

Coordination with BNSF Railway and Union Pacific Railroad is taking longer than anticipated. The railroad companies own the right-of-way under the bridge, and because of this, we are required to obtain access permits from each railroad company to work around and within their right-of-way. The permit prohibits construction work on the bridge from taking place from the Argo rail yard below the bridge if it disrupts rail yard operations, which means that we need to complete most of the repairs from the bridge deck. This arrangement makes the design and construction of the bridge repairs more complex. Thank you for your patience.

Project overview

The 4th Ave S Bridge, or 4th Over Argo Rail Yard Bridge as it's commonly known, was first built in 1933 and serves as a connection between Georgetown and Downtown Seattle. In 1985, the bridge lanes were changed to its current configuration of two lanes each direction. Over time, the bridge has experienced higher volumes of vehicles and heavier trucks. The higher volumes and increase loads as well as the bridge’s aging have caused deterioration of the bridge over time. We inspected the deterioration and concluded that the outside lanes of the bridge could no longer safely support the vehicle loads it was carrying.

Public safety is our top priority, and in 2017 we decided to completely close the northbound curb lane and restrict large trucks from using the southbound curb lane to help reduce further deterioration of the piers.

Project Map

Project map for 4th Over Argo

The short-term and long-term solutions

The short-term solution to this situation is to reduce the load on the outer edges of the bridge. This means that vehicles going northbound must merge into the inside lane. People driving passenger vehicles going southbound can still use the curb lane. However, large trucks and buses are required to merge into the inside lane. We expect this configuration to continue to be in place until repairs have been completed.

In the long term, we are planning to rehabilitate the segment of the piers that directly supports the outer edges of the bridge. This work requires extensive coordination with the railroad since the bridge spans across an active rail yard and railroad tracks that support freight trains as well as commuter rail and Amtrak. Our permit with the railroads prohibits us from working in the Argo rail yard below the bridge, if it disrupts railroad operations. Because most of the repairs need to be made from the top of the bridge, these conditions have made the design and construction more complex than anticipated. We currently have a consultant on board to help us finalize the repair plans.

Taking alternate routes

Prior to closing the curb lane, the bridge was seeing nearly 17,000 daily users in both directions. Since the northbound lane closure and southbound restrictions, the number of daily users has decreased by about 25% in both directions. This means commuters have started using alternate routes or taking alternative modes of transportation to and from Downtown and South Seattle.

Please consider giving yourself extra time to travel, working with your employer about changing your work hours, or finding alternative means to get to work such as riding a bike, walking, carpooling, vanpooling, or taking public transit. For more information, please visit: www.seattle.gov/traffic.

Schedule and construction

We are finalizing the design for the repair of the 4th Ave S Bridge. Coordination with the railroad companies is taking longer than anticipated with two railroad companies having rails below the bridge. We expect to finalize the design later in 2022 and begin construction in 2023.