• Project

I-90 – SR 18 Interchange Improvements

The westbound Interstate 90 off-ramp to State Route 18/Snoqualmie Parkway will close from 9 to 11:59 p.m. Tuesday, Sept. 10, to install an overhead sign structure. A signed detour will be available, with more details on our Travel Center Map.

Snoqualmie Parkway will be reduced to a single lane with flaggers alternating traffic and intermittent 15-minute closures from 12;01 to 5 a.m. Wednesday, Sept. 11, to install another overhead sign structure just north of the I-90/SR 18 interchange.

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 is building a diverging diamond interchange and adding two lanes on SR 18 between the interchange and Deep Creek.

Timeline
2022 - 2025
Project status
Construction
Funding
$188 million
Project hotline

What to expect

Building the diverging diamond interchange and widening SR 18 will be accomplished through several stages of construction during which travelers can expect traffic shifts, speed reductions and intermittent lane and ramp closures throughout the life of the project.

Congestion will increase during construction, so people should plan extra time for trips or find alternative routes.

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