All lanes of State Route 18 will be closed in both directions under the Interstate 90 bridges from May 29 through June 4.

The closure will allow crews to work on the southern section of the diverging diamond interchange, according to the Washington State Department of Transportation. The completion of the diverging diamond — an interchange where drivers drive on the opposite side of the road while crossing the interstate — has already been postponed. It is now expected to open this summer.

“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,” according to WSDOT. “It also reduces the chances that opening the new interchange is delayed.”

The closure was originally scheduled for May 15-21, but was rescheduled due to forecasted rain.

WSDOT says drivers should expect delays and plan extra time for their commutes during the upcoming closure. Traffic exiting I-90 on the eastbound off-ramp will only be able to go south on SR18, and traffic exiting I-90 on the westbound off-ramp will only be able to turn north onto Snoqualmie Parkway

There will be detours available for those wanting to go the closed directions.

Drivers can avoid the closure by looping around at the Preston-Fall City interchange and the SE North Bend Way interchange, according to WSDOT.

For real-time traffic information, download the WSDOT app or visit WSDOT’s statewide travel map.