Snoqualmie drivers should expect traffic delays and plan for extra time in the I-90/SR 18 interchange area beginning June 7, 2023, as Washington State Department of Transportation (WSDOT) contractor crews ramp up work on the I-90/SR 18 Interchange Improvements Project that will widen the highway and redesign the interchange.
To prepare for SR 18 widening, crews will close the truck climbing lanes throughout the project, reducing traffic to one lane in each direction on SR 18 near the interchange. Starting Wednesday, June 7, the eastbound lane will close, and on Friday, June 9, the westbound lane will close. These long-term SR 18 lane closures are also anticipated to result additional traffic congestion on I-90 near the interchange.
Additionally, drivers should expect slight traffic shifts on SR 18 during the daytime commute and intermittent nightly lane reductions as early as 8 pm, Mondays through Thursdays, with lane reopening by 5 am. Flaggers will direct motorists when traffic is reduced to one lane.
Another lane closure related to the project will occur on westbound I-90 near Preston, where the left lane will close each day from 9 am to 7 pm, Mondays through Thursdays, for utility work. Additionally, flaggers will alternate traffic on Upper Preston Road at the I-90 overpass from 8 am to 4 pm, Mondays through Thursdays, June 5-15.
I-90/SR 18 Interchange Improvements Project
When complete in 2025, this project will improve safety and keep traffic flowing through the busy corridor by creating a Diverging Diamond Interchange and widening SR 18 from I-90 to Deep Creek. A second phase of the project will then widen SR 18 from Deep Creek to Issaquah Hobart Road, which is expected to be complete in 2029 at which point all of SR 18 will be a safer, 4-lane highway.