Projects - State / Other Sponsored
Modeling Sound Due to Over-Snow Vehicles in Yellowstone and Grand Teton National Parks
The National Park Service has been increasingly concerned about the winter use of Yellowstone and Grand Teton National Parks - particularly the increased use of snowmobiles in the parks and various legal actions brought by environmental, recreational, governmental, and commercial groups. Although snowmobiles and snow coaches, collectively referred to as over-snow vehicles (OSVs), can facilitate the enjoyment of these parks for many visitors, they can also undermine the experience for others and impair the condition of park resources; therefore care must be taken in determining acceptable over-snow vehicle use in the parks. In order to try to maintain a balance between the positive and negative effects of OSV use in the parks, Winter Use Plans have been developed which include various OSV restrictions. As an aid to the current judicial decision making process, Volpe Acoustics has conducted extensive modeling using a modified version of the Federal Aviation Administration’s Integrated Noise Model (INM) Version 6.2 , which was adapted for use with OSVs. This modeling allowed for the comparison of a wide-range of OSV management scenarios (different volumes, vehicle types, and travel routes).
Sponsors: NPS Yellowstone and Grand Teton National Parks
Exterior Sound Level Measurements of Over-Snow Vehicles at Yellowstone National Park
Sounds associated with Oversnow Vehicles (OSVs), such as snowmobiles and snowcoaches, are an important management concern at Yellowstone and Grand Teton National Parks. The Volpe Center is supporting the National Park Service (NPS) with implementation of the Winter Use Planning program. Volpe Acoustics recently performed sound level measurements of ten snowcoaches and six snowmobiles at Yellowstone National Park. These measurements were made with three primary objectives: 1) Help determine what sound testing protocols should be used to determine if snowcoaches meet the Best Available Technology (BAT) with respect to noise emissions, 2) Determine which snowcoaches currently operating in the parks met BAT standards with respect to noise emissions, and 3) Determine if there was a significant difference between snowmobile sound levels when tested using two different methodologies.
Sponsors: NPS Yellowstone and Grand Teton National Parks
ADOT PCC Surface Treatment and "Quiet" Asphalt Study, Ongoing
Supporting the Arizona Department of Transportation (ADOT), the Volpe Center Acoustics Facility first conducted a study to determine differences in tire/road noise levels for three Portland Cement Concrete (PCC) pavement surface treatments. It is common practice to apply surface treatments to increase the safety of highways paved with PCC, allowing for better friction than untreated surfaces. Although different surface treatments are somewhat interchangeable from the safety aspect, there can be large variations in the resulting highway noise levels. For this study, acoustical data were collected on the side of a closed highway, and a fleet of 30 vehicles drove through each section of pavement multiple times at varying speeds. Averages of the vehicles' maximum sound levels were used to determine the "loudest" and "quietest" surface treatments. In conjunction with results obtained from vehicle noise source measurements taken right at the tire (performed by ADOT and other organizations), the results provided by the Volpe Center Acoustics Facility allowed ADOT to change their standard practice for treating PCC pavement surfaces, ultimately resulting in lower noise levels in communities next to highways.
Following the PCC surface treatment study, ADOT started a Quiet Pavement Pilot Program (QPPP), a research program partnering FHWA and ADOT to study the noise reducing effects of rubberized asphalt. A rubberized asphalt overlay was applied to PCC highways throughout the Phoenix metro area. The Volpe Center is conducting field measurements at two research quality highway sites, measuring the sound levels of real, free-flowing traffic, before and after the overlay application, to quantify the noise reduction. These measurements are being conducted near the highway and at community sites, including a park and elementary school. The sound levels are being measured over time to determine the longevity of the noise reducing effect. Volpe Center results, along with results being generated by ADOT and other organizations, will help ADOT to define the use of rubberized asphalt for noise abatement, including changes in policy and noise prediction.
Sponsor: ADOT, Transportation Research Center
Caltrans "Quiet" AC Pavement Study, Ongoing
Supporting the California Department of Transportation (Caltrans), the Volpe Center Acoustics Facility is conducting a study to determine the noise reduction benefits of "quiet" Asphaltic Concrete (AC) pavements. Typically, noise barriers along highways are used to reduce traffic noise propagating into neighboring communities. By introducing "quiet" pavements into highway projects, tire/road noise can be reduced at the source, also benefiting nearby communities. In some cases, pavement may be the only feasible noise mitigation tool.
For the Caltrans "Quiet" AC Pavement Study, tire/road noise is measured on the side of an open highway. Twice a year for five years, simultaneous measurements are performed in five adjacent sections of the highway, each with a different AC pavement overlay. Among other parameters, the noise reduction benefit of each of the pavements is investigated in terms of pavement age, pavement composition, and vehicle type. Ultimately, this study will contribute to a choice of pavement to be used throughout the State of California and will help build new federal policy on the use of "quiet" pavements to reduce highway traffic noise.
Sponsor: Caltrans, Environmental Program
