Updated: I-90/SR 18 Interchange Ramps To Undergo Nightly Closures Sept. 25-29 for Construction

UPDATE: The overnight closures of the westbound I-90 on-ramp from SR 18/Snoqualmie Parkway and the eastbound I-90 off-ramp to westbound SR 18 have been rescheduled due to inclement weather. This story has been edited to reflect the updated schedule.


Commuters using the I-90/SR 18 interchange should brace themselves for potential disruptions starting Monday, Sept. 28. The ramps will have nightly closures from 9 p.m. to 5 a.m., lasting through Oct 2nd.

The project, spearheaded by the Washington State Department of Transportation (WSDOT), aims to establish a diverging diamond interchange near Snoqualmie.

“These closures are necessary so construction crews can begin work on the new diverging diamond interchange,” the department said in an official release. “They will close the ramps to temporarily realign traffic, creating space for work zones.”

Closure details
Contractor crews postponed ramp striping originally scheduled to begin at 9 p.m. Wednesday, Sept. 27 due to inclement weather. 

From 9 p.m. Thursday, Sept. 28 to 5 a.m. Friday, Sept. 29, the westbound I-90 on-ramp from SR 18/Snoqualmie Parkway will close while construction crews stripe new ramp lanes for a temporary traffic shift.

From 9 p.m. Monday, Oct. 2 to 5 a.m. Tuesday, Oct. 3, the eastbound I-90 off-ramp to SR 18/Snoqualmie Parkway will close while construction crews place concrete barrier to separate traffic from the work zone.

As the project progresses, commuters will likely observe several changes. Among these will be lane shifts, shrunken shoulder widths, and a temporary concrete barrier designed to separate traffic from ongoing construction. Nevertheless, “crews will maintain lane widths and the number of lanes on the ramps,” WSDOT confirmed.

It’s crucial for drivers to heed the reduced speed limits set during the construction phase: a cap of 30 mph from the interchange to the Lake Creek bridge and 45 mph from the Lake Creek bridge to Deep Creek.

The overarching project, which also includes highway widening, bridge construction, and enhancements to wildlife connectivity along SR 18, is anticipated to wrap up by early 2025. Following its conclusion, a subsequent project will oversee the widening of SR 18 up to the Issaquah-Hobart Road Southeast.

Stay informed
WSDOT will announce closures in advance on the WSDOT app, travel center map and in project email updates. For questions or concerns, call the project hotline at 206-216-4545.

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