摘要: |
As a consequence of the rapid urbanization of the greater Jackson, Wyoming area, the hazard, to motorists and WYDOT maintenance personnel, from an active avalanche path at milepost 151 on U.S. 89-191 has increased dramatically. U.S. 89/191 is a principal arterial in and out of Jackson with an annualized average daily traffic (AADT) of 11,000. Winter use, though considerably less, is still significant. The purpose of this project was to develop, design, and test of the feasibility of deploying on-site structures that would disrupt the flow of the southerly wind that carries snow into the milepost 151 avalanche starting zone. Snow sails are a form of passive avalanche starting zone defense, designed to use the inherent energy of the wind to disrupt the snowpack in an avalanche starting zone and inhibit the formation of coherent, continuous avalanche wind-slabs. A plot phrase deployment of four snow sails was initially installed in the 151 avalanche starting zone. The performance of these snow sails was evaluated in terms of their ability to disrupt the snowpack. These sails disrupted the snowpack depositional pattern sufficiently that a full deployment of 50 sails was subsequently installed. A snow sail performance assessment and evaluation was conducted. This assessment and evaluation lead to the following results: The snow sails have reduced the 151 avalanche hazard, but have not eliminated it. The 151 site continues to avalanche to the road, at a rate of 1.0 per year, versus 1.5 per year prior to snow sail installation. The following recommendations are made: When severe winter storms occur, the 151 site should be addressed with (artificial explosive) avalanche control measures. The snow sail project-an attempt to address the 151 avalanche hazard with a cost-effective solution has partially achieved its goals. However, investigations into novel and traditional avalanche hazard reduction technologies for implementation at the 151 site is warranted. |