SNOQUALMIE, Wash. — State Route 18 is back open in a wider configuration over Tiger Mountain.
There are now two lanes in each direction between Interstate 90 and Deep Creek. Crews also installed a permanent center barrier between eastbound and westbound SR 18 that will help improve safety through the corridor. That barrier stretches from north of the Lake Creek bridge to south of the Deep Creek bridge.
The opening marked a significant milestone for the I-90/SR 18 Interchange Improvements project.
Construction to widen this section of SR 18 began in 2023, but traffic did not shift into its final configuration until a four-day closure of the highway, which wrapped up early Monday, Oct. 20.
To add the new eastbound and westbound lanes, crews constructed new four-lane bridges that improved fish passage along Lake Creek and Deep Creek beneath SR 18 and a new two-lane bridge over Raging River next to the existing bridge.
The $188 million project still has several items that need to be completed:
- Final paving through the I-90/SR 18 diverging diamond interchange, including the I-90 on- and off-ramps.
- Final paving along both directions of SR 18 between I-90 and Deep Creek.
- Permanent lane striping.
- Installing landscaping, curbs, and guardrail.
These tasks and other minor items are scheduled to be completed in 2026 once the weather improves.
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