Snoqualmie residents who use the I-90/SR 18 interchange at night should plan more time for their trips next week when WSDOT will close the on-ramps to both westbound and eastbound I-90 as work on the new diverging diamond interchange begins.
The nighttime closures begin Monday, Sept. 25, at 9 pm when the ramps will undergo four overnight closures.
Closure Details
From 9 pm to 5 am each night, Sept. 25-29, crews will close I-90 ramps at the SR 18/Snoqualmie Parkway intersection. A signed detour will direct people to use eastbound I-90 and use exit 27 to access westbound I-90 and SR 18. [Snoqualmie residents can also detour to I-90 by using SR 202 to access exit 22 in Preston.]
- The westbound on-ramp to I-90 will close nightly Sept. 25-27, Monday to Wednesday.
- The eastbound off-ramp to I-90 will close Thursday, Sept. 28 to Friday, Sept. 29.
Diverging Diamond Interchange
These closures are necessary so construction crews can begin work on the new diverging diamond interchange. They will close the ramps to temporarily realign traffic, creating space for work zones.
During this stage of construction, drivers will notice lane shifts, reduced shoulder widths and temporary concrete barrier separating traffic from construction activities. Crews will maintain lane widths and the number of lanes on the ramps.
Crews will also continue working along SR 18 to widen the highway, build bridges and improve wildlife connectivity. Drivers should follow lowered speed limits during construction: 30 mph from the interchange to Lake Creek bridge; and 45 mph from Lake Creek bridge to Deep Creek.
This project is expected to be complete in early 2025. A separate project will finish widening SR 18 to Issaquah-Hobart Road after the first project is complete.