UPDATE: WSDOT has cancelled the five day closure of SR 18 scheduled for May 15-21 due to forecast rain. The closure will be rescheduled and an update will be posted when the dates are set.
Original story below:
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Both directions of State Route 18 near Snoqualmie will close around the clock for more than five days beginning May 15 near Interstate 90 to build the southern end of a new diverging diamond interchange.
This extended closure should allow crews to complete the interchange portion of the I-90/SR 18 Interchange Improvements project this summer, according to a May 2 Washington State Department of Transportation (WSDOT) news release.
From 9 p.m. Thursday, May 15, through 5 a.m. Wednesday, May 21, traffic will not be allowed on either direction of SR 18 beneath the I-90 bridges.
The work requires dry weather and may be rescheduled if it rains.
The extended closure will eliminate the need for 10 consecutive nights of ramp and intersection closures near the interchange and fewer traffic shifts, which improves safety for workers and people driving through the work zone. It also reduces the chances that opening the new interchange is delayed.
During the closure, contractor crews working for WSDOT will install new drainage and electrical crossings, pave the new roadway and build concrete islands that will form a portion of the new I-90/SR 18 diverging diamond interchange. The work also includes constructing a left turn pocket for traffic turning from westbound SR 18 onto Southeast 104th Street and a signalized U-turn south of I-90 that will allow eastbound SR 18 traffic to head westbound toward Auburn.
The extended closure will allow both the left turn pocket from westbound SR 18 to Southeast 104th Street and the signalized U-turn to westbound SR 18 to open while work on the rest of the interchange is completed.
Detour options
People can detour around the closure using eastbound and westbound I-90 and loop around at the Preston-Fall City (exit 22) and Southeast North Bend Way (exit 27) interchanges.
Westbound I-90 freight traffic should use either the Preston-Fall City exit to loop back and take westbound SR 18 or continue on westbound I-90 to southbound I-405. Freight traffic should not use Issaquah city streets or Issaquah-Hobart Road, which are not suitable for semi-trucks. Similarly, eastbound SR 18 freight traffic cannot use Issaquah city streets to access I-90.
All people traveling through the I-90/SR 18 interchange during the closure should expect delays and add time to their travel plans. Real-time traffic information is available on the WSDOT app and WSDOT’s statewide travel map and social media channels.
When SR 18 reopens Wednesday, May 21, most of the construction on the southern end of the new interchange will be complete. Work remains under the I-90 bridges and on the northern end of the project before traffic can be shifted into the final diverging diamond configuration later this summer.