Effective at 9 p.m. Sunday, a five-mile stretch over Snoqualmie Pass will be reduced from four lanes to one lane in each direction for most of the week. Transportation planners say that could lead to huge delays.
The six-day lane closures are needed as crews put finishing touches on the freeway at mileposts 54 and 57.
"We have to actually pave the ends, move a lot of barriers around. We have to finish some drainage work," says Don Whitehouse with the state Department of Transportation.
The state DOT is warning drivers to plan ahead for big delays. They admit it's inconvenient -- but they say it will pay off.
Crews have cut away about 800,000 cubic yards of rock to make way for an extra lane in each direction.
"Two summers worth of work right here," says Whitehouse. "Bringing it down little bit at a time to get us to this wider roadway ... We've done a lot of rock molding to make sure it's safe."
DOT officials says it's all part of a $551 million project to widen the five-mile stretch of I-90 between Hayak and Keechelus Dam. They say drivers will notice things running smoother this year when it starts snowing.
"What motorists are really going to see this winter is a huge expanded truck chain-up area. That's always been a problem on this pass," says Whitehouse.
And when those lanes reopen next Friday at 7 a.m., the state DOT says the 27,000 drivers who use I-90 over Snoqualmie Pass each day will have a newer, safer way to travel.
"Just the added lanes, the added shoulders, the chain-up areas," says Whitehouse. "We have some nice big ditches now. It's just going to be a lot better now for people traveling across the pass."
The entire I-90 project is expected to wrap up in fall 2017.