• Project

I-90 – SR 18 Interchange Improvements

Tree clearing to widen SR 18 will occur Feb. 6 through March 2023. Drivers should expect intermittent lane closures and additional congestion through the project area. The westbound truck climbing lane south of I-90 will be closed:

Daily, from 8 a.m. Monday, Feb. 6 to 3 p.m. Saturday, Feb 11 for soil inspection

From 5 a.m. Monday, Feb. 13 through 5 a.m. Thursday, Feb. 16 for tree clearing

The westbound shoulder south of the interchange will close daily from 9 a.m. Monday, Feb. 6 to 3 p.m. Thursday, Feb. 9 for tree clearing

Project overview

Growth in Snoqualmie Valley has made the I-90/SR 18 interchange one of the busiest in the state, causing backups during peak times and busy travel weekends. To improve traffic flow, WSDOT will build a diverging diamond interchange and add two lanes on SR 18 between the interchange and Deep Creek.

2022 - 2025
Project status
$188 million
Project hotline

What to expect

Building the diverging diamond interchange will require two full weekend closures of SR 18 between I-90 ramp intersections. Widening SR 18 will require lane shifts, speed limit reductions, and closing one northbound lane north of Raging River Bridge. Additional information including detour routes will be available during construction.

Reconstructing the I-90/SR 18 interchange will improve safety performance and travel times on I-90, SR 18 and Snoqualmie Parkway.