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Spokane St Swing Bridge is now fully reopened after repairs successfully completed.

by on September 15, 2024
Crew members move the repaired gate arm segment back onto the bridge while another crew member prepares the undamaged gate arm for reattachment.

The Spokane St Swing Bridge is fully reopened after our crews repaired damage from a car crash on the evening of September 14.

Nearby Construction Updates and Detour Maps:

Update (9/20/2024)

The Spokane Street Swing Bridge reopened to vehicle traffic at 2:45 p.m. on Sept. 20.

Work on the South Spokane Street Viaduct will continue as planned with lane closures in both directions throughout the weekend.

Many thanks to our SDOT crew members who worked diligently to repair the damage caused by a car crash the evening of Sept. 14.

The damage occurred when a vehicle drove through the warning gates and onto the bridge while it was swinging open and hit the metal barricade. The barricade prevented the speeding vehicle from driving off the bridge, but the collision severely damaged the mechanical gate, lock mechanism, gate control panel, and sensors that are essential for safe bridge operations. 

Update (9/19/2024)

Our engineers and maintenance crews have been making ongoing progress on repairing the damaged gate.

We have also released the tentative closure schedule for this weekend’s paving work on the nearby Spokane St Viaduct (the elevated structure connecting the West Seattle High-Rise Bridge to I-5). If the repairs to the low bridge are not completed by then we will scale back some of this work so people will still be able to get on the West Seattle High-Rise Bridge from SODO.

Earlier this week we separated the gate arm into two segments and took the damaged arm segment to our repair shop. We then removed the internal machinery and repaired or replaced each component as needed.

We received the replacement steel housing yesterday and technicians worked throughout the day to complete the necessary modifications to make it compatible. We modified the steel housing with new cutouts and support brackets and then installed the interior machinery including the gate’s motor, linear actuator (the component that extends to lock the gate in place), sensors, and wiring.

Technicians cut access holes and weld support brackets into the replacement steel housing.
Technicians cut access holes and weld support brackets into the replacement steel housing.
Crews place the two halves of the gate arm in position so that they can be re-attached.
Crews place the two halves of the gate arm in position so that they can be re-attached.

Today we will begin reattaching the repaired arm segment to the segment that was not damaged in the crash. After the gate is physically reattached there will still be a lot of electrical work to complete, such as rewiring the components, fixing damaged connections, and re–installing the sensors and switches.

We will not know for sure whether the repairs have been successful until we’ve completed the reassembly and the entire system is tested. There are electronic sensors inside the mechanical gate arm that act as safeguards and prevent the bridge from operating without a functional gate. If there is damage to the mechanical or electrical components that we did not observe during the disassembly, we will likely discover it during this testing.

Each step we complete will bring us more confidence about our progress and when we can reopen the bridge to cars and trucks.

Crew members move the repaired gate arm segment back onto the bridge while another crew member prepares the undamaged gate arm for reattachment.
Crew members move the repaired gate arm segment back onto the bridge while another crew member prepares the undamaged gate arm for reattachment.

Update (9/17/2024)

This morning crews removed the segment of the mechanical gate which was critically damaged in Saturday’s car crash on the Spokane Street Swing Bridge. We moved the gate to our repair shop where internal mechanical components will be removed, examined and either repaired or replaced. 

If the repairs are not completed before the weekend, crews would continue working on repairs over the weekend and we would reduce the scale of work on the nearby Spokane St Viaduct paving project to make sure that people have access to get on the West Seattle High-Rise Bridge from SODO.

A crane with 10 tons of lifting capacity loading the critically damaged vehicle barricade onto a truck so it can be taken to our repair shop.
A crane with 10 tons of lifting capacity loading the critically damaged vehicle barricade onto a truck so it can be taken to our repair shop.

The impact forced the locked gate out of its socket, damaging the interior machinery and dragging the extended locking pin across the concrete wall. The barricade absorbed the full force of the speeding vehicle, preventing it from driving off the end of the bridge.

The vehicle gate is filled with mechanical and electrical components which were badly damaged. After a new housing is built, the repaired and replaced components will be re-assembled in the housing. While this is being done, crews will also be rewiring and repairing the damaged control panel that is attached to the pivot point of the mechanical gate.

Scratches gouged into a concrete wall where the gate locking pin was dislodged from its socket and dragged across the concrete.
Scratches gouged into a concrete wall where the gate locking pin was dislodged from its socket and dragged across the concrete.
Control panel with dislodged mechanical rotary gear, fuses, sensors, and mounting plate.
Control panel with dislodged mechanical rotary gear, fuses, sensors, and mounting plate.
This photo shows a bent metal shaft called a “linear actuator” that extends or retracts the large steel pin that locks the gate.
This photo shows a bent metal shaft called a “linear actuator” that extends or retracts the large steel pin that locks the gate.

Update (9/16/2024)

SDOT engineers and maintenance crews continue to make repairs necessary to reopen the Spokane Street Swing Bridge to cars and trucks. Crew members may not be visible onsite all the time because much of the manufacturing and repair work is conducted offsite.

The damaged metal gate at the end of the bridge must be removed and will either be replaced or rebuilt in our mechanical repair shop. The impact critically twisted and bent the main metal tube which is the backbone of the mechanical gate. The electronics, motor, and locking pin linear drive motor inside the metal tube were also damaged in the crash. All these components are essential for safe bridge operations.

Due to the complex and precise nature of the work, crews are unable to repair the gate in its present location. We plan to remove the gate arm tomorrow and take it to our repair shop where the motors and moving parts can be dismantled, evaluated and repaired if possible. At the same time, other crew members will be focusing on repairing the damaged gate control panel and wiring.

As an extra precaution, we are ordering replacement parts in case the gate and or its electrical and mechanical components can’t be repaired, or if a replacement turns out to be the quicker and better option. Many of these mechanical parts are highly specialized and complex components which are not readily available locally and we are still waiting for confirmation from the manufacturer of some of the components.

It is not safe for drivers to use the bridge without a safety gate. Additionally, there are electronic sensors inside the mechanical gates which act as safeguards and prevent the bridge from operating without a functional gate.

We do not know the exact timeline when the repairs will be completed but expect the repairs to take several days. We will continue to provide in-depth updates as repairs continue.

Bent and twisted mechanical gate arm with damaged linear driver motor, wiring, warning lights, and control panel.
Bent and twisted mechanical gate arm with damaged linear driver motor, wiring, warning lights, and control panel.

Original Post (9/15/2025)

The Spokane St Swing Bridge (also known as the West Seattle Low Bridge) will remain closed to motor vehicles as our crews continue to repair damage from a car crash on the evening of September 14. On Sunday, crews completed initial repairs allowing bicycles and pedestrians to use the bridge and enabling ships to request a bridge opening.

Our engineers and maintenance crews are making swift progress on repairs to the bridge. While work is moving forward efficiently, technicians do not expect to be able to reopen the bridge within the next few days and are continuing to develop a more exact timeline.

Cars and trucks should follow the detour route and use the West Seattle High-Rise bridge to travel across the Duwamish Waterway. Harbor Island can still be accessed from the east via S Spokane St coming from the SODO neighborhood. 

The damage occurred around 7:00 p.m. on Saturday, September 14 when a vehicle drove through the warning gates and onto the bridge while it was swinging open and hit the metal barricade. The barricade prevented the speeding vehicle from driving off the bridge, but the collision severely damaged the mechanical gate, lock mechanism, gate control panel, and sensors that are essential for safe bridge operations.

Pedestrians and bicyclists access to the bridge was restored late Sunday afternoon. People may notice pedestrian signals will say “don’t walk” even when the pedestrian gates are open and the bridge is properly locked in place for land travel. This is due to damaged sensors in the vehicle gate. The engineers are working to correct the signal issue, but rest assured it is safe for bicycles and pedestrians to cross when the pedestrian gates are open and there are no flashing lights or warning bells. 

Filed Under: SDOT, Traffic and Construction Tagged With: , ,