WOLF CREEK PASS CORRIDOR TUNNEL AND ROADWAY

SH 160/Wolf Creek Pass, Colorado

Lyman Henn provided complete design and construction inspection services for an eight mile long section of the the Wolf Creek Pass Project on Highway 160 in Colorado . The project included a 908-ft long two lane tunnel and extensive sections of rock cuts up to 200-ft high, soil nail retaining walls, boulder walls and mechanically stabilized earth (MSE) walls. In addition, challenging foundation conditions required deep foundations below some of the wall structures.

The Upper Narrows Tunnel provides two traffic lanes in a bi-directional configuration and was excavated through volcanic tuff bedrock. Excavation was accomplished using drill and blast methods in multiple drifts, with rock bolts and shotcrete for initial support and cast-in-place concrete final lining. The tunnel also has safety and life support systems including emergency egress adits, a ventilation system, lighting, and monitoring.

The major rock cuts and ground nail walls in close proximity to the existing highway were constructed in an environmentally and visually sensitive setting.  Lyman Henn designed the geotechnical parts of the project. Specific tasks included design of rock cuts, reinforcement and rockfall mitigation that were visually acceptable to the U.S. Forest Service. Lyman Henn provided field engineering support including consultation on rock blast designs, recommendations for scaling and rock bolting of cut faces, observation of ground nail wall construction, and oversight of field testing for rock bolts and ground nails. During construction, Lyman Henn also worked with CDOT and the US Forest Service to improve the visual appearance of the rock cuts by eliminating half-casts and using rock staining.