More work to be done on Cosi Hill; should open to two-way traffic in spring 2022

Two way traffic will be returning to Cosi Hill, although more work is planned this month to allow for that.

The Washington State Department of Transportation says that repairs will soon be underway on a slide-prone section of US 101 outside Cosmopolis. 

They say that by spring 2022, two-way travel will be restored once again to the popular freight corridor.

On Monday, Aug. 16, Washington State Department of Transportation contractor crews will begin work to stabilize the hillside near milepost 78.

Since January of 2020, work has been done on this stretch of US 101, and Cosi Hill has been reduced to single lane with a temporary traffic signal due to chronic roadway settlement. 

The roadway sits on a pre-historic landslide. Heavy rains triggered the highway to drop more than five feet. With the alternating traffic, there are long delays for travelers.

WSDOT conducted a thorough investigation of the site. Because of the frequency and severity of slide activity, a careful approach was required. WSDOT hydraulic, geotechnical and transportation experts collaborated to produce a solution that would withstand significant movement after heavy rains.

“Our crews will place 45 steel beams up to 43 feet into the ground to form what engineers call a ‘soldier pile wall,’” said WSDOT Project Engineer Karen Boone. “This is when the steel beams are lined up one-by one to imitate a line of soldiers.”

WSDOT implemented this solution in a previous slope stabilization project in 2015 along US 101 at Rock Crusher Hill.

The $5.8 million slope stabilization contract was awarded to Quigg Bros, Inc. earlier this summer.

Travelers can expect to see weekday daytime construction. A temporary signal will alternate people, which is currently in place, through spring 2022. Any highway closures will be announced in advance. No work is currently scheduled for weekends or holidays.

Grays Harbor County travelers are encouraged to sign up for email updates. Real-time traffic information is available on the WSDOT app and WSDOT regional Twitter account.