PLANNED INSTRUMENTATION OF SNOW-SUPPORTING STRUCTURES IN JACKSON, WYOMING

United States (US) has limited experience and lacks approved design guidelines for the design and implementation of snow supporting structures (SSS). In terms of guidelines, the preemi- nent document on the implementation of SSS is the Defense Structures in Avalanche Starting Zones: Technical Guideline as an Aid to Enforcement, which is known as the Swiss guideline. The Swiss guideline is a fully mature and comprehensive design guideline and serves as an invaluable starting point for the development of the guidelines and specifications for the design of SSS in the US. In 2011, a series of 87 SSS were designed for deployment at the Milepost 151 avalanche site on US Route89/191 near Jackson, Wyoming (the MP151 site). To reduce the visual impact at the MP151 site, the configuration of the SSS was designed in a manner that mimics visual elements of the natural landscape. This is in contrast to the Swiss guideline, which suggests configurations that result in a relatively orderly and repeating pattern of snow bridges in landscapes. This organic configuration raises questions as to the applicability of the Swiss guideline as a basis for predicting the snow loads upon which these SSS were designed. To address this, two of the structures will be instrumented with a series of vibrating wire strain gauges, pressure plates, and thermistors, electrical strain gauges, and snow depth sensors with the objective of providing additional field data towards the drafting of a US guideline for the design of SSS. To date, the instrumentation has not been installed due to delays in the construction activities.