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We just finished up a full closure of Interstate 405 to build a new fish culvert. Now it’s Interstate 90’s turn for delays and lane closures for a new culvert of its own.

Workers were able to put in the culvert on I-405 in just three days.  The will take three-and-a-half years because workers have to dig down 60 feet under all of I-90 and smaller roads on either side of the freeway. That can’t be done in three days.

More Chokepoints: All lanes of I-405 were closed between Renton and Bellevue last weekend 

The eastbound HOV lane has been closed for a while as the contractor prepared for the work. Now it’s time for the first of several lane shifts for construction.

Early Wednesday morning, all eastbound lanes will move to the left into a newly paved stretch of road. The Washington Department of Transportation’s Seth Belknap said this is the first shift as they will build the culvert in stages.

“The main goal of the project is to improve the fish passage and the wildlife habitat in Sunset Creek by removing the barrier culvert that runs underneath it,” Belknap said.

This is one of the state’s most ambitious fish passage projects to date.

“We are constructing four bridges, one on westbound I-90, one on eastbound I-90 as well as one on Southeast 36th street and southeast Eastgate Way,” Belknap said.

The work will be done in stages to keep traffic moving.

“The main goal is to keep people moving on I-90 as well as the local streets, so we will be constructing the bridges in halves essentially and shifting traffic around the work zone,” he said.

For the next several months, all eastbound traffic will be moved to the left. Then it will be shifted to the right for the next stage.

Larry Smith is the project manager for the contractors at Atkinson Construction.

“We’ll dig down a little bit, enough room to get an abutment put in and some girders set, and then we’ll build the deck,” Smith said. “That allows us to detour traffic on top of it.  We’ll have shallow foundations, precast girders, and a cast-in-place deck. We will then flop to the other  half and build it.”

The eastbound lanes should be finished later this year.

More on the I-90 Culvert: Ambitious fish passage work begins under I-90 in Bellevue

“On westbound I-90 in early 2024, we will look to close the HOV lane there and will follow a similar structure where we’re shifting traffic for the first part of the westbound I-90 bridge and then shift them back up to the north,” Belknap said.

The westbound work on I-90 should be done in late 2024 or early 2025, but the work on the side streets on the north and south side of I-90 will be closed longer, extending the project into 2026.

Southeast 36th Street, which is by the T-Mobile campus, will have one-lane, alternating traffic for about 18 months. Construction will begin this fall.

Eastgate Way on the north side of I-90 will be closed for six months starting in 2025. This will make it difficult to get to Bellevue College and the park and ride.

Check out more of Chris’ Chokepoints.