Drivers using State Route 18 near Interstate 90 over the next two months will find a 2-mile section reduced to a single lane on weeknights.

SR 18 will be reduced to a single lane with alternating traffic on weeknights near Tiger Mountain summit, as work begins on the last of three bridges to widen a 2-mile section of SR 18 just south of I-90, according to the Washington State Department of Transportation (WSDOT).

Beginning Wednesday night, Jan. 31, the westbound lane of SR 18 will close from 9 p.m. to 5 a.m. Monday nights through Friday mornings until the end of March. People should plan for up to 20-minute delays, as a pilot vehicle will alternate traffic through a single lane along a 2-mile stretch between Lake Creek and Deep Creek.

During the lane closures, contractor crews working for the WSDOT will begin work on a new four-lane bridge at Deep Creek. Crews also will continue work on the new two-lane bridge that will span Raging River and have already finished the new four-lane bridge crossing Lake Creek, just south of I-90.

The new bridges replace culverts that blocked fish passage in Deep Creek and Lake Creek and create pathways for wildlife to pass under the highway instead of across it.

Work at the interchange

As SR 18 widening continues, crews also are working at the I-90 interchange on drainage systems and drilling foundations for the new diverging diamond sign bridges.

This work is part of our ongoing effort to widen the entire 7-mile stretch of SR 18 between I-90 and Issaquah-Hobart Road Southeast. The current project will build a new diverging diamond interchange and widen the first 2 miles of SR 18 to the south of I-90. It is expected to finish in 2025.