Author(s):
Mr. Blase Reardon - US Geological Survey
Daniel B. Fagre - U.S. Geological Survey
Abstract:
In January 2004, natural avalanches blocked U.S. Highway 2 and derailed a freight train in John F. Stevens Canyon, on the southern boundary of Glacier National Park. The railroad tracks were closed for 29 hours due to cleanup and lingering avalanche hazard, backing up 112km of trains and shutting down Amtrak’s passenger service. The incident was the latest in a 94-year history of avalanche accidents in the canyon; these have had local and regional economic effects and include three fatalities and the destruction of a major highway bridge. Despite that history, avalanche hazard mitigation in the canyon is limited to nine railroad snow sheds and limited highway engineering. The lack of explosive testing or control is one of several factors that have created a rare record of large magnitude natural avalanches over the past century. Others include protected lands, transportation infrastructure, Maritime and Continental climates, and large but shallow starting zones. This case study combines data from historic records, field measurements and observations, a Natural Resources Conservation Service (NRCS) SNOTEL station, and data collected since 2001 at a high-elevation weather station. It describes the physical characteristics of the avalanche paths in the canyon and the weather patterns that create natural avalanche cycles. It summarizes how recent incidents and changing economic factors have prompted a unique partnership of land management agencies, private corporations and non-profit organizations to develop an avalanche mitigation program for the transportation corridor. Lastly, it examines how natural avalanche activity has varied over the past 94 winters.
