The I-68 Sideling Hill rock cut is famous for its impressive geologic display, exposing layers of sedimentary rock folded in a broad syncline. It is also deep, steep, and eroding—posing hazards to both motorists on I-68 below and anyone attempting to climb its slopes to assess their stability. Schnabel was hired by the Maryland Department of Transportation State Highway Administration to conduct a rock slope hazard assessment and remediation concept development for this pair of 360-foot-high, 1,200-foot-long rock cut slopes, the largest in Maryland.
We developed a 3D computer model of the rock cut using a land-based LiDAR (laser). The model allowed us to evaluate the rock face more accurately and safely than would have been possible if we climbed it. The information the model produced served as the basis for our development of three primary rockfall mitigation options:
- The first option involved rock scaling, bench cleaning, and removal of vegetation to prevent roots from wedging farther into rock crevices
- The second option would install flexible rockfall barriers at the toes of the slopes
- The third option called for installation of draped wire rockfall mesh
We also presented additional design ideas for spot-treatment of isolated rockfall hazards, such as spot bolting, shotcrete surface protection with drainage, and anchored rockfall nets.