John A. Volpe National Transportation Systems Center (U.S.)

Tech Report

Wyoming

Final report; Oct 2006

United States. National Park Service

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.

PDF

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

VX82-CM355

Volpe National Transportation Systems Center, Technical Reference Center