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2009 Environmental Excellence Awards

For Excellence in Environmental Research: Development of Technology for Measurement of Tire/Pavement Noise Using the On-Board Sound Intensity Method

Agencies Awarded

California Department of Transportation (Caltrans)

Illingworth & Rodkin, Inc.

General Motors (GM)

Arizona Department of Transportation (ADOT)

Caltrans' Division of Environmental Analysis adapted a little-known GM measurement methodology to precisely quantify tire/pavement acoustics. The new methodology, On-Board Sound Intensity (OBSI), is based on acoustic work done on test tracks in the 1970s by GM. The dominant noise source on light vehicles operating at freeway speed is tire/pavement noise. The noise levels on different pavements can vary widely depending on material type and surface texture. It was this tire/pavement noise phenomenon that led Caltrans to develop OBSI. The Caltrans-modified approach uses one standard tire to evaluate many different pavements with traffic on active freeways in real time. The unique aspect of this procedure allows pavement noise to be separated from other noise generators on a moving vehicle. This work has demonstrated that lowering pavement noise levels also lowers community noise adjacent to highways. Development of quieter pavement is another potential tool that transportation departments may use to lower overall traffic noise levels in the community. A better understanding of tire/pavement acoustics will improve noise-modeling calculations and noise-mitigating design features. This Caltrans-/GM-developed process is now being adopted as a measurement standard by the American Association of State Highway and Transportation Officials (AASHTO), ASTM International (formerly the American Society for Testing and Materials), and SAE International (the Society of Automotive Engineers International).

Project Contributors:

Caltrans
Randell Iwasaki
G. Scott McGowen
Bill Farnbach
Bruce Rymer
James Andrews
Illingworth & Rodkin, Inc.
Dr. Paul R. Donavan
GM
Douglas B. Moore
ADOT
Larry Scofield

Photo of man using sound intensity device on a car tire. Second photo shows device connected to tire.

Updated: 12/03/2012
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