The Interstate 90/State Route 18 Interchange Improvements project will reach a major milestone next week when the first ramps of the new diverging diamond interchange open to traffic near the city of Snoqualmie.
First up is the SR 18/Snoqualmie Parkway on-ramp to westbound I-90, which will switch to the new ramp configuration overnight Monday, Sept. 9. Next will be the eastbound I-90 off-ramp to SR 18, which changes to the new configuration overnight Thursday, Sept. 12.
Once the new ramps open at 5 a.m. the following morning, people should remain distraction-free and pay attention to the new striping and signs. The new on- and off-ramps are the first pieces of the new diverging diamond interchange to open to traffic. The full interchange is expected to open in early 2025.
A busy week of nighttime work
In addition to the two ramp switches, contractors working for the Washington State Department of Transportation will install overhead structures to hold new signs that will help direct drivers through the new interchange. These will be placed above the eastbound and westbound I-90 off-ramps to SR 18 and Snoqualmie Parkway north of I-90.
People traveling through the I-90/SR 18 interchange at night next week should expect the following closures:
Overnight Monday, Sept. 9
- The SR 18/Snoqualmie Parkway on-ramp to westbound I-90 will close from 9 p.m. Monday, Sept. 9, through 5 a.m. Tuesday, Sept. 10, to switch to the new ramps. A signed detour will use eastbound I-90 and loop around to westbound I-90 at Winery Road/North Bend Way (exit 27).
- SR 18 will be reduced to a single lane, and flaggers will alternate traffic near the I-90 interchange from 9 p.m. Monday, Sept. 9, through 5 a.m. Tuesday, Sept. 10, to unload and set a concrete barrier.
Overnight Tuesday, Sept. 10
- To install an overhead sign structure, the westbound I-90 off-ramp to SR 18/Snoqualmie Parkway will close from 9 to 11:59 p.m. Tuesday, Sept. 10. A signed detour will continue on westbound I-90, loop around at Preston/Fall City (exit 22) and use the eastbound I-90 off-ramp to SR 18.
- Snoqualmie Parkway will be reduced to a single lane with flaggers alternating traffic from 12:01 to 5 a.m. Wednesday, Sept. 11, to install an overhead sign structure. All northbound and southbound lanes will close intermittently for 15 minutes as the structure is lifted into position.
Overnight Wednesday, Sept. 11
- The eastbound I-90 off-ramp to SR 18/Snoqualmie Parkway will close from 9 p.m. to 11:59 p.m. Wednesday, Sept. 11, to install an overhead sign structure. A signed detour will continue on eastbound I-90, loop around to westbound I-90 at Winery Road/North Bend Way (exit 27) and use the westbound I-90 off-ramp to SR 18.
- The SR 18 on-ramp to eastbound I-90 will close from 12:01 to 5 a.m. Thursday, Sept. 12, to remove light poles. A signed detour will use westbound I-90 and loop around to eastbound I-90 at Preston/Fall City (exit 22).
Overnight Thursday, Sept. 12
- The eastbound I-90 off-ramp to SR 18/Snoqualmie Parkway will close from 9 p.m. Thursday, Sept. 12, to 5 a.m. Friday, Sept. 13, to switch to the new ramp. A signed detour will use westbound I-90 and loop around to eastbound I-90 at Preston/Fall City (exit 22).
Real-time travel information is available via the WSDOT mobile app, the WSDOT Travel Center map or by signing up for WSDOT’s email updates.
[Information provided by the Washington State Department of Transportation. Featured ImageDesign rendering of the I-90/SR 18 diverging diamond interchange looking east. Courtesy, Aecon.]
Comments
What is the plan for Highway 18 after the interchange is complete. Tiger Mountain Pass both directions traffic bogs down as you cross the pass. The volume of traffic is so high over the pass that narrowing to one lane on each side creates tremendous danger to people on that roadway. This looks like a very simple fix, than the stop reduction by completing the slow lanes, the stop and go merge chaos cost time, productivity, and lives. It needs to be addressed as a priority. and the action needs to be taken.