WSDOT is permanently closing the express lanes along I-90 to make way for Sound Transit’s new light rail line that will connect Seattle to Redmond by 2023.

The move will push 15,000 more cars onto the mainline. To account for that increase, WSDOT is adding one new HOV lane in each direction.

The first thing drivers will notice is the new lanes are about a foot narrower, so there will be less room for error. The shoulders are narrower as well, so if there is an accident or a breakdown, at least part of a lane will be blocked.

“That's a big concern,” said Leslie Bernstein, who lives just off the freeway on Mercer Island. “What happens with accidents? It's going to be a big mess.”

Analysts say the changes should add about 10 minutes to the commute between Seattle and Bellevue, but Sound Transit's Rachelle Cunningham said it will all be worth it in about six years.

“It's going to give people a reliable option,” she said. “People can take the train and avoid congestion completely.”

Analysts said they expect it to take about a month for people to get used to the new changes.

In the short term, there are going to be various closures to I-90 all weekend long while crews perform finals test on the bridge. Drivers are told to expect delays, especially with the Mariners and Sounders in town this weekend, along with the Susan G. Komen walk in Seattle on Sunday.

More information is available here.