4th Ave S Bridge Planning Study
Updated August 12, 2025
What's Happening Now?
We’re starting to engage neighbors to collect feedback that will inform our planning process. Our goal is to carefully consider the needs of everyone who relies on the bridge—including community members, local businesses, freight and industrial stakeholders, emergency services, and nearby residents—to develop a replacement plan that serves all users. We aim to create a plan that:
- Makes the bridge stronger and safer for everyone: The 4th Ave S Bridge is showing its age and can no longer safely support the demands of modern traffic. We aim to restore full travel capacity and ensure safe travel for all users.
- Meets modern standards and addresses seismic resilience: The plan will incorporate current seismic and transportation standards to handle heavier vehicles and more traffic.
- Preserves a critical link between Georgetown and Downtown: This bridge has been an essential connector for freight, commuters, and other community members for over 90 years. This project will help keep that connection strong and reliable for decades to come.
We invite you to learn more and share your thoughts at our upcoming community open house:
Open House Details:
- Date: Thursday, September 4, 2025
- Time: 4:30 - 6:00 PM
- Address: SODO BIA Office, 2450 6th Ave S #100, Seattle, WA 98134
We look forward to seeing you there and hearing your feedback!
Project Overview
The 4th Ave S Bridge—also known as the 4th Over Argo Rail Yard Bridge—has served as a vital connection between Georgetown and Downtown Seattle since it was built in 1934. Spanning 1,750 feet over 21 active railroad tracks (5 BNSF and 16 Union Pacific), it is a critical route for both commuters and freight.
Over time, the bridge has experienced significant wear and tear, particularly from heavy truck traffic and increasing vehicle volumes. Cracking in parts of the structure has led to lane closures and load restrictions, reducing the bridge’s capacity by 25%. In 2017, the outside northbound lane was closed due to a crack in the pier wall. A 2019 study classified the bridge as functionally obsolete.
This planning study will evaluate replacement options that improve safety, reduce disruption, and meet today’s engineering and seismic standards.
In addition to this planning effort, SDOT is also working on a separate 4th Over Argo Rail Yard Bridge Repair Project which will provide near-term repairs to extend the structural integrity of the bridge until it is replaced or rebuilt.
Project Area
Funding
This project is funded by a $2.4M federal grant from the Federal Highway Administration’s Bridge Investment Program. This grant will fund roughly 75% of this planning work, with locally sourced funding covering the rest of the project’s budget.
Project Timeline
| Project Milestone | Estimated Timeframe |
| Select six bridge replacement alternatives to study more | July 2025 |
| Refine the six bridge replacement alternatives down to three | October 2025 |
| Final Replacement Study Report | Fall 2026 |