Update 5: W Seattle Lower Bridge

Weighty Subject

Today, the Roadway Structures crew is moving a 15-ton replacement cylinder into its exact place, inside the west shore pier house of the W Seattle Lower Bridge.

The bridge was swung out to its marine vessel position last Wednesday, to further investigate a hydraulic fluid leak.

Roadway Structures crew maneuvers 15-ton cylinder | June 25, 2018

Roadway Structures crew maneuvers 15-ton cylinder | June 25, 2018




Photo by Casey Allen | Pexels

Maneuvering replacement parts the combined weight of two elephants is no simple task. The nearly 30,000-pound cylinder must be installed per specific controls, right down to cleaning it, along with reconnecting hydraulic oil lines, rewiring electrical conduit, etc.

Huge piston assembly cylinder must be clean for install.


There’s also continuous monitoring and testing along the way (not of the elephants; rather, operation of the 15-ton replacement cylinder). It all means there are several more days of hard work ahead.


4 x 12 Effort

On Saturday, the team worked a 4th consecutive 12-hour day, pulling the huge, damaged piston assembly out of its tightly placed spot, and delivering the new one to just inside the pier house dome. With such long hours and critical work, the team rested Sunday to ensure both a safe and successful effort kicking off again this morning.


The damaged piston assembly cylinder will be inspected in detail locally, to determine to cause of its hydraulic fluid leak.


What You Can Expect

The Spokane St Swing Bridge, a.k.a. W Seattle Low-Level Bridge over the Duwamish River, remains out of commission, potentially through the end of the week. We expect to know more tomorrow, June 26, 2018.


 Detour routes are marked at the following locations:

  • Chelan Ave SW
  • 1st Ave S
  • E Marginal
  • Harbor

Visit our What’s moving Seattle this week? blog for navigation tips.



 Shuttle service for bike commuters is running during the week, 6 – 10 AM and 3 – 7 PM, carrying up to 15 passengers each trip.

 Shuttle pick-up & drop-off is at bridge approaches; arriving at each side every ~20 minutes.

For biking around the Duwamish River to the next cross point, see our Bike Detour Map and suggestions in Update 4


Here’s to a successful West Seattle Lower Bridge Repair this week, coming back strong and swinging!