Landslides are common geologic hazards that often greatly impact transportation routes. The impacts may range from minor maintenance issues to long-term closure of the route. Effective mitigation of landslides requires the engineering geologist to recognize and adequately characterize landslide deposits and landslide-prone topography. The site characterization is necessary to construct an accurate conceptual model of the present and future geologic setting. The model should provide the engineering geologist and design engineer the information necessary to evaluate future stability or, if required, stabilization schemes.

A good conceptual model is based on a well designed investigation program and includes accurate data and interpretation of geomorphic history, water conditions, material properties, shear strength parameters of the soil/rock mass, topography, material thickness, and discontinuities. It also requires predictions of how these properties might change in the future. Observation of past and present processes at and surrounding a site along with an understanding of slope performance under similar conditions in the region is important. Monitoring of conditions and/or movement may be necessary over time. This presentation will discuss several case studies from the Rocky Mountain region that illustrate how a conceptual geologic model can be constructed that is useful in estimating risk and stability.