Travel Advisory | Helping you plan ahead for upcoming Washington State Department of Transportation work on the 1st Ave S Bridge (SR 99 / SR 509 Duwamish River Bridge)

Upcoming WSDOT work will result in lane reductions and closures for southbound 1st Ave S Bridge: 

All southbound lanes will be closed from 9 PM to 6 AM on the nights of Friday, March 5 and Saturday, March 6 

Two of four southbound lanes will be closed continuously from noon on Wednesday, March 10 to noon on Monday, March 15 

All southbound lanes will be closed from 9 PM to 5 AM on the nights of Sunday, March 14 and Monday, March 15 

There will be no impacts to northbound lanes of the 1st Ave S Bridge. 

We’re making this a little easier. During the overnight closures of the 1st Ave S Bridge on the nights of March 5, March 6, March 14, and March 15, the Spokane St Swing Bridge (low bridge) will be open to all vehicles.

This means we’ve made a temporary change to help with the impact of this closure. On the nights of Friday, March 5 and Saturday, March 6 the Spokane St Swing Bridge (low bridge) will be open to all vehicles an extra hour – from 9PM to 6AM. (Normally, the low bridge is open to all vehicles from 9PM to 5AM nightly.)

Starting Friday, March 5, the Washington State Department of Transportation (WSDOT) will begin making repairs on the 1st Ave S Bridge (also known as the State Route 99 / State Route 509 Duwamish River Bridge). 

The 1st Ave S Bridge is a major north-south route through Seattle and serves as part of the West Seattle High-Rise Bridge detour route over the Duwamish Waterway for people traveling to and from West Seattle. To learn more about this project and why WSDOT is making these repairs, visit their project website

Here is what to expect on the 1st Ave S Bridge. 

The work will require closures and lane reductions on the southbound bridge. Work does not affect the parallel northbound bridge. 

  • All southbound lanes of the 1st Ave S Bridge will be closed from 9 PM to 6 AM on the nights of Friday, March 5 and Saturday, March 6 
  • Two of four southbound lanes will be closed continuously from noon on Wednesday, March 10 to noon on Monday, March 15 
  • All southbound lanes will be closed from 9 PM to 5 AM on the nights of Sunday, March 14 and Monday, March 15 

Here’s a map showing the location of the work in relation to the West Seattle High-Rise Bridge.  

Planning ahead: We know travel options are limited while the West Seattle High-Rise Bridge is closed, and we’re doing all we can to keep you moving. 

WSDOT recommends that travelers consider other alternative routes, such as the E Marginal Way S Bridge, the Tukwila International Boulevard Bridge, I-5, and the South Park Bridge, especially during peak afternoon hours. 

If you can, please shift your travel times, drive an alternate route, or take another mode of transportation to help reduce congestion and the environmental impacts it has in the Duwamish Valley.  

If you do need to drive during these lane reductions and closures, please know you are driving through communities that are already significantly impacted by the high bridge detour traffic. Let’s work together to respect the people who live and work in communities along the detour route by: 

  • Driving slowly  
  • Observing traffic signs 
  • Stopping for people walking, rolling, and biking, especially at every intersection even if it is not a marked crosswalk. 

We’re doing our part to make traveling safer and smoother on the high bridge detour route by repairing potholes, limiting or restricting other SDOT construction activity, and getting the message on our electronic signs in the area.  Throughout the upcoming WSDOT work on the 1st Ave S Bridge, we’ll be monitoring travel patterns 24/7 to make signal timing changes and deploying response crews as need when we see congestion. 

We’re making this a little easier. During the overnight closures of the 1st Ave S Bridge on the nights of March 5, March 6, March 14, and March 15, the Spokane St Swing Bridge (low bridge) will be open to all vehicles.   

This means we’ve made a temporary change to help with the impact of this closure. On the nights of Friday, March 5 and Saturday, March 6 the Spokane St Swing Bridge (low bridge) will be open to all vehicles from 9PM to 6AM. (Normally, the low bridge is open to all vehicles from 9PM to 5AM nightly.)

Please remember: We really don’t want you to get a ticket! Other existing low bridge travel restrictions will remain in place during this WSDOT work.  

  • As always, our priority for the Spokane St Swing Bridge (low bridge) is to keep a reliable and clear route for emergency vehicles, public transit, and freight. If you are not authorized to use the low bridge, you will receive a $75 citation every time you cross. 
  • The low bridge is open for you at all times if you’re riding transit, in a vanpool, walking, rolling, riding a foot scooter, or biking.  

THIS MEANS

During the overnight closures of the 1st Ave S Bridge on the nights of March 5, March 6, March 14, and March 15, the low bridge will be open to all vehicles.  

Any other time, the low bridge restrictions remain the same and if you are not authorized to use the low bridge, you will receive a $75 citation every time you cross.  

It’s even more important to only use the low bridge if you are authorized to do so while construction is occurring on other routes. This is because – without the restrictions – there would be an even greater strain on the low bridge’s extremely limited capacity. 

The 1st Ave S Bridge is managed by WSDOT. To learn more about this project, visit their website.