Wind ‘speed limit’ on I-90 bridge confuses drivers

MERCER ISLAND, Wash. — Any day on I-90 can be an adventure of sorts. The day after a major closure due to high winds, well, that’s a different story.

“I would say it`s kind of hellish,” said Sarah Wang, a Mercer Island resident who uses the floating bridge highway to get to work.

The bridge was closed Sunday after winds reached into the 40 mph range and waves crested at 2 feet.

I-90 is normally graded as safe for north winds up to around 45 mph, but new construction for the Eastlink light rail changes conditions, according to Sound Transit.

According to WSDOT, the bridge will be closed if:

“We hit a new threshold of sustained winds from the north of at least 26 mph (that north detail is very important and does not happen often) for two minutes and observe waves of at least 2 feet, we will not allow traffic onto the westbound I-90 bridge between Mercer Island and Seattle. Emergency vehicles will have access to the bridge at all times.”

The transportation agency says “wind and wave analyses performed during Sound Transit’s East Link design process showed the pontoons on the westbound I-90 bridge are susceptible to damage during strong north wind events.”

WSDOT says there is no immediate safety risk to the public or bridge, but that the strong north winds could damage the bridge — shortening its lifespan.

Joris Van de Bospoort nearly got stuck.

“I was going to rush and go through I-90. But I wasn't allowed. I was really surprised by that. I went through 520. Had to pay the toll,” he said.

We found a safety study from the early 1980s that almost predicted what happened Sunday: Icy air and heavy northern winds.

It's supposed to be rare, but Wang wants clarity on what wind speed will close the bridge so she can prepare

“So everyday we're like,  can we take this route, or do we have to take that route?" she said.