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West Seattle. You’re on notice. The low bridge is about to close for nine days for much-needed upgrades.

The Lower Spokane Street swing bridge will close at 12 a.m. Friday, April 19. It will remain closed until 12 a.m. Sunday, April 28. That’s two weekends and a full work week where the low bridge will be out of commission.

This isn’t the first time the bridge has been shut down for  over the Duwamish River.

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“We actually have a lot of exciting new elements happening over at the Lower Spokane swing bridge,” Seattle Department of Transportation (SDOT) Regional Director for Roadway Structures Kit Loo said. “They tried to make it more resilient, but also just to replace a lot of the old aging infrastructure and the mechanical electrical elements associated with the bridge.”

Workers have already replaced some cylinders that help the bridge turn. Now it’s time to work on all the wiring for the control and communications system.

“It’s basically the computer system, all the knobs and all the push buttons, everything that the bridge operator needs to utilize in order to open and close the bridge,” Loo said. “We’re basically replacing the entire system.”

The old control tower wires were actually strung on the high bridge. They have been moved to a conduit under the Duwamish River.

“We fished the new line through already, and we’re in the process of splicing it,” Loo said.

It’s that system replacement that will be completed during the upcoming nine-day closure.

To make sure SDOT can get it put in during this closure, Loo said they built a mock control system off-site and tested it so they know what to expect.

“We had a bridge operator go down there and actually test the system to see if they could break it,” Loo said.

This is expected to cause delays for people heading into and out of West Seattle. There is also freight impact for trucks heading to Terminal Five on Harbor Island.

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People should add extra time to their trips.

“There’s going to be some congestion on the High Bridge during the normal weekday, during that closure, but we have a detour route and have worked with Port of Seattle to get the detour routes in place,” Loo said.

The biggest impact of this closure, other than the truck traffic, will be the bicyclists and pedestrians. Metro is offering those communities free daily round-trip passes. You can use the and use rewards code LOWBRIDGE24 to get your free passes.

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