Tunnel 34 shown with visible deterioration in 2022 before project start.
Moon Pass Tunnels, Bridge and Rockslide Repair
Geotechnical and engineering geology services to stabilize slopes and rehabilitate aging tunnels in rural Idaho.
GeoEngineers is providing geotechnical and engineering geology services for the Moon Pass Road Tunnels and Bridges project, which will rehabilitate and repair eight 100-year-old tunnels deep in the mountains of North Idaho.
Originally built for the railroad in the early 1900s, these narrow tunnels were eventually repurposed as part of the US Forest Service Road System and are now maintained and operated by Shoshone County. In recent years, rockfalls and concrete deterioration have caused closures and safety concerns. The Idaho Transportation Department, LHTAC, and Shoshone County issued a joint RFP to address potential hazards inside the tunnels, improve rock slope stability at the tunnel portals and approaches, and repair the substructure of a bridge.
Approach
GeoEngineers is designing tunnel and roadway mitigation strategies that will include scaling, rock bolts and shotcrete, rockfall barriers, draped mesh, concrete liner rehabilitation and/or replacement, and monitoring protocols.
Results
Project design is expected to begin in spring 2024 and continue through fall 2026, with construction scheduled for summer 2027.
