Information from Seattle Department of Transportation

We Successfully Reinstalled & Restored a Refurbished Turn Cylinder

Summary:

• In early March, we reinstalled the refurbished cylinder that was removed last fall. During this work, the low bridge remained open to people walking, rolling, biking, and driving.  
• In April, crews will reroute the control tower wires from the high bridge to a new conduit beneath the West Duwamish Waterway that connects to the motors that open and close the bridge.
• Planning, design, and construction for the initial phase of the Spokane St Swing Bridge Rehabilitation Program took place from 2020 to 2022.
• Subsequent phases of this work will continue into 2025.

Between March 1-3, 2024, crews successfully reinstalled the refurbished cylinder that was removed during the October 2023 low bridge closure!  We will continue to rehabilitate the remaining two turn cylinders in the west bridge pier this year.

Last October, we reinstalled the refurbished cylinder from the east pier that was damaged when the piston head became stuck in January 2023. When the unexpected damage occurred, preparations to overhaul all four of the bridge’s hydraulic turning cylinders were already underway as part of our comprehensive repair and maintenance efforts. This allowed for repairs to be completed sooner than if we had started from scratch. Our bridge maintenance crews, and our design and repair experts redeveloped a part of the turn cylinder so that this type of malfunction is much less likely to occur in the future. 

This communication line is linked to the control system, which opens and closes the low bridge. The original system, composed of buttons, switches, and wires, is about 30 years old. To remedy this, we will be rerouting the wires connecting the control tower with the motors that open and close the bridge off the high bridge to a new conduit under the West Duwamish Waterway. This work will increase the resiliency of the West Seattle Bridge system and help decouple the low bridge from the high bridge. 

The system includes computers that control the machinery that lifts and swings the spans and activates the gates that prevent traffic and people from crossing when the low bridge is open. It also includes the communication lines that connect the computers, control tower, and the moving parts to one another.

By making these updates, we are proactively addressing the risk of potential component failures associated with operating the bridge. We will share more details about the timing of this upcoming closure as planning efforts continue.