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.
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.