The West Seattle Bridge is closed after crews noticed increasing cracks and deterioration in the aging structure.

SEATTLE —

Though he was "reluctant to speculate" on a timeline for when short- or long-term solutions to the West Seattle Bridge closure would be implemented, Seattle Department of Transportation Director Sam Zimbabwe said the issue will "likely outlast" the coronavirus pandemic.

During a city council briefing March 30, Zimbabwe said he didn't want to give the impression that the bridge closure is something the department will be able to handle in the next few weeks.

"It's going to be something that will outlast the public health emergency," he said. "Which is why we need to be thinking about traffic mitigation..."

Some of those mitigation measures have already been implemented. SDOT installed a new traffic signal at SW Holden and Highland Park Way SW to manage the increase in traffic there. Officials are also asking ship traffic to avoid requesting passage past the lower swing bridge during peak travel times.

The high-rise portion of the West Seattle Bridge is closed until further notice, city officials announced Monday, March 23. It had been developing cracks over time and further deterioration was detected recently.

“There are concerns that the high-rise bridge cannot safely support vehicular traffic at this time,” Seattle Mayor Jenny Durkan said.

But SDOT stressed there is no danger of imminent collapse - at least while traffic is kept off the span.

Spokane Street (the lower swing bridge) will remain open to transit, some commercial freight traffic and first responders only.

Eastbound traffic will need to use the 1st Ave S. bridge or South Park bridge, and westbound traffic from I-5 will need to exit at the Michigan/Corson Exit to access West Seattle.

Lisa Herbold, the councilmember representing West Seattle, stressed the importance of connecting the peninsula with the rest of the city. Current detours add about 5 miles to most trips, especially for folks living in the North Admiral area.

“This is a second emergency, layered upon this COVID-19 emergency,” Herbold said.

Still - officials stressed that most people must avoid the Spokane St. bridge - if it's jammed up, emergency responders trying to reach West Seattle quickly won't be able to get through. Normal commute traffic demands can easily overwhelm the capacity of this route, officials said.

"If everyone is trying to use the lower bridge, then no one can use the lower bridge," Zimbabwe said.

“After learning today that the Seattle Department of Transportation was indefinitely closing the West Seattle Bridge due to structural concerns, I directed King County Metro to immediately begin planning alternate routes on both sides of the Duwamish, and to increase the frequency of and connections to the King County Water Taxi," said King County Executive Dow Constantine.

SDOT crews will need to make a further assessment of when the bridge will be safe for driving again. One solution could include a carbon fiber wrapping for the failing area, which is then coated with an epoxy to make a shell.

"The extent and the type of cracking we've seen has concerned our structural engineering experts,” said Zimbabwe.

SDOT said there is also some potential that once a temporary fix is in place, some lanes could reopen.

Zimbabwe said the department has been monitoring some cracking in the bridge for years and they have been doing preventative maintenance. However, rapid growth in the cracks led to the closure.

“That type of growth in a reinforced concrete structure is completely unacceptable,” said Matt Donahue with SDOT. “That’s typically the type of growth you see over years, not weeks and days.”