Rock Instability Forces Emergency Closure of 97-A at Knapps Hill Tunnel

Road may be closed for up to a month

Information from WSDOT and LCN; photo above courtesy of Ray Dobbs

The increasing severity and frequency of recent rock fall on US 97A south of Knapps Hill Tunnel required the full closure of the highway from milepost 223 to 230.  This closure began at 2:30 p.m. Thursday (5/14). While there is no scheduled date for the reopening, WSDOT Maintenance Supervisor Rob Swagert said the road could be closed for up to a month.

The roadway was cleared of debris on Thursday and work crews also deliberately placed large rocks at both tunnel entrances to ensure drivers can’t attempt to get through. 

Historically, there has been some rock fall at this location, often associated with weather conditions. In recent months, the frequency of the rock slides, and the size and amount of debris that comes down has increased. The Washington State Department of Transportation has now also identified larger boulders that have been exposed and undermined by the slides, increasing the likelihood that these rocks will fall on the road. 

Early this spring, WSDOT developed a plan to mitigate rock fall at the tunnel. The design for this work is complete and construction was scheduled for August or September 2020.  With the emergency closure of the roadway, WSDOT is currently working to accelerate the project in the coming weeks.

The tunnel closure also comes at a time when WSDOT crews are scheduled to begin work next week on a rock scaling project at three separate locations on Highway 97-A between Entiat and Knapps Tunnel.