Design and performance monitoring of snow-supporting structures for the Milepost 151 Avalanche near Jackson, Wyoming

Mitigation of risk associated with snow avalanches in the United States has traditionally required intensive effort by winter maintenance crews during peak storm periods to forecast and subsequently release high-risk avalanche sites with explosives. Though the approach is common in Europe, a novel approach in the United States is to implement avalanche starting zone structures to hold the snowpack in place and prevent the release of an avalanche. This approach eliminates the need for active management of the avalanche and frees up resources during winter storms. The Wyoming Department of Transportation has embraced the use of this technology for the Milepost 151 Avalanche near Jackson, Wyoming. This paper describes the critical aspects of the design of snow-supporting structures (SSSs) and details a research project that is under way to monitor both snowpack conditions and the resulting quasistatic snowloads on one SSS by using field instrumentation. The instrumentation includes transducers to measure snow pressure, strain gauges to measure SSS axial strains, and snow depth gauges to track snowpack depth immediately uphill of the SSS. Preliminary results from winter season 2014-2015 are presented, and their impact on the design of SSSs is discussed.