• Project

I-90 – SR 18 Interchange Improvements

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
$147 million

What to expect

Widening SR 18 will require lane shifts, speed limit reductions, and closing one northbound lane north of Raging River Bridge. Building the diverging diamond interchange will require four full weekend closures of SR 18 between I-90 ramp intersections. 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.