Bus riders lost 90 minutes to delays, Harbor Island freight trucks idled in a lineup back to Interstate 5, and commuting motorists found extra congestion on their everyday detour routes, after the lower West Seattle swing bridge malfunctioned Wednesday morning.

Bridge crews solved the immediate problem and completed test openings, and spokesperson Mariam Ali said, “the bridge is currently fully operational” at 10:57 a.m., about 2½ hours after the closure began.

SDOT found that an electronic sensor delivered an error message to a computer that controls bridge movements, she said in an update late Wednesday afternoon.

The low bridge, built in 1992, uses an unorthodox swing design, where two spans pivot on huge hydraulically operated cylinders that move within precise tolerances. In recent years there also have been occasional malfunctions of conventional parts, including the roadway gates.

When the low bridge closed, that left zero bridges directly off the West Seattle peninsula where about 100,000 people live. The seven-lane high-rise bridge closed March 23, 2020, because of runaway structural cracks, and it is supposed to reopen in summer 2022 after repairs, although SDOT has yet to announce a date.


General traffic already was diverted down West Marginal Way Southwest, toward the South Park neighborhood and the First Avenue South drawbridge — a six-mile detour for anyone driving downtown.

Wednesday morning’s glitch gave bus riders a taste of that misery, when King County Metro dispatchers sent busy routes C, 120 and others toward that distant bridge instead of the Spokane Street swing bridge.

For instance, a Route C bus with 50 passengers left a stop near the West Seattle Golf Course around 8:25 a.m. and didn’t reach Sodo until 9:50 a.m., even though Metro drivers bypassed a general-traffic lineup and snaked into the queue farther ahead, in the spirit of Washington state’s “yield to buses” law.

Since the high-rise bridge closure, the low swing bridge has been restricted to buses, trucks, emergency vehicles, and a limited number of permitted business and maritime workers. Wednesday’s glitch caused those users to overflow into the longer detour and increase crowds on Marginal.

Such problems undermine an SDOT strategy, expressed this past week on postcards, to “Flip Your Trip” by taking transit. However, the West Seattle Water Taxi worked smoothly as an alternative Wednesday. In hopes of lowering car volumes, SDOT encourages travelers who either live or work in certain neighborhoods, including West Seattle, to claim a $25 credit online at seattletraffic.org/flipyourtrip to use toward transit, van pools, or rental scooters.

Traffic entering West Seattle was also bottlenecked, and drivers waited more than a mile on the West Marginal detour route. Trucks and cars stopped south of the Duwamish Longhouse before crawling into the five-way Chelan Avenue Southwest intersection.


The Spokane Street Bridge has occasionally malfunctioned in the two years of the main West Seattle Bridge closure.

Engineers at SDOT, for years, have called for various upgrades to the bridge that are finally funded and scheduled during 2022.

These include carbon-fiber wrapping of cracks in the concrete girders; a new power control system; and rewiring of communications cables between the control tower and the low bridge.