Final report; Oct 2006

NTL-ENERGY AND ENVIRONMENT-Environment Impacts ; AGR-PUBLIC AND TRIBAL LANDS-PUBLIC AND TRIBAL LANDS ;

A modified version of the FAA’s Integrated Noise Model (INM) Version 6.2 was used to model the sound of over-snow vehicles (OSVs) (snowmobiles and snowcoaches) in Yellowstone and Grand Teton National Parks for ten modeling scenarios provided by the National Park Service (NPS). Version 6.2 was modified to incorporate ground-to-ground sound propagation models consistent with propagation over snow-covered terrain (40 cgs rayls) for OSVs. Sound level relationships were developed for OSVs relating maximum Aweighted sound level (LAmax) to vehicle speed and distance from observer. Audibility and LAmax contours were generated and rank ordered for the ten modeling scenarios according to percent of park covered by a particular contour. In general, the use of Best Available Technology (BAT) OSVs, the reduction in the number of active paths, and the reduction in number of operations all reduced audibility in the parks. These results are expected to help the NPS in refining their winter use plans for the Parks.

https://www.nps.gov/yell/learn/management/upload/finalsound%20_modelingreport.pdf

Volpe