SDOT making contingency plans in case West Seattle Bridge becomes in danger of collapse

SEATTLE — Nearly a month after abruptly closing the West Seattle Bridge because of cracks, the Seattle Department of Transportation is developing worst case scenario plans in case the bridge becomes in imminent danger of collapse.

That danger is not here now.

But city officials say the cracks, which they quietly monitored for years, are still growing even after they closed the bridge to traffic.

"At the moment, right now, the bridge is not in imminent danger of collapse," said Heather Marx, SDOT's director of downtown mobility. "But we want to be prepared for the worst case scenario because we still don't fully understand what is causing the crack growth even after we've removed traffic from the bridge."

That crack growth is slower than before the closure, and soon the city will have monitoring equipment on the bridge to more quickly track changes.

If the bridge appears closer to falling, the city's contingency plans call for evacuating anyone within 225 feet of either side of the bridge, including businesses and marinas.

In that scenario, traffic would stop on West Marginal Way, a key detour that runs beneath the bridge.

The lower Spokane Street Bridge, now officially open only to buses and trucks, might also be shut down.

City officials say when the lower bridge opens for barges and boats, it swings beneath the high bridge.

If there's a collapse risk, marine traffic would be stuck upriver.

"This is not imminent," Marx said. "We are planning for the worst case scenario in an abundance of caution."

The city could have a better idea later this year whether the bridge can be saved, or if it will need to be torn down and replaced.

Regardless of what happens long term, when the coronavirus crisis eases and people commute again, West Seattle's street system will be overwhelmed by drivers taking detours.

"The system simply cannot handle the same volume of traffic that we handled in the pre-COVID world," Marx said.

City officials plan a virtual town hall about the West Seattle Bridge closure Wednesday evening.

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