Investigations of Environmental Effects on Freeway Acoustics

The study reported here was designed to examine the impact of background meteorological conditions on the propagation of noise from urban freeways in the Phoenix area. The aim was to understand and predict how sound waves emanating from highways respond to the vertical profiles of atmospheric temperature gradients and velocity shear, so that sound measurements can be interpreted with regard to the environmental variability. Over the course of four days in late 2006 and two days in early 2007, field experiments were carried out at two freeway sites, where meteorological data and sound levels were measured and recorded from early morning until the middle of the day. Such periods span the stable, morning transitional and convective periods of the atmosphere. From the data collected, three test cases of varying atmospheric density stratification and wind shear are presented and discussed. These cases represent all measurement periods and were analyzed in detail. A parabolic equation model coupled to a Green’s function model close to the source field was developed and used to compute the refracted sound field for experimental cases up to half a mile from the freeway, permitting computations of noise exposure of residential areas nearby. The model demonstrates that atmospheric effects are able to raise sound levels by 10dB–20dB at significant distances from the highway, which at times led to exceeding acceptable limits imposed by Federal Highway Administration for residential areas. Mitigation strategies such as barriers and asphalt rubber friction course (ARFC) are also briefly discussed.

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• Record URL:
  • https://rosap.ntl.bts.gov/view/dot/23987
• Corporate Authors:

  Arizona State University, Tempe

  Office for Research & Sponsored Projects Administration
  P.O. Box 873503
  Tempe, AZ  United States  85287-3503

  Arizona Department of Transportation

  206 South 17th Avenue
  Phoenix, AZ  United States  85007

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Fernando, H J S
  • Ovenden, N C
  • Shaffer, S R
• Publication Date: 2010-3

Language

• English

Media Info

• Media Type: Digital/other
• Edition: Final Report
• Features: Bibliography; Figures; Maps; Photos; References;
• Pagination: 52p

Subject/Index Terms

• TRT Terms: Acoustic emission; Field studies; Freeways; Meteorological phenomena; Noise; Sound level
• Geographic Terms: Phoenix (Arizona)
• Subject Areas: Environment; Highways; I15: Environment;

Filing Info

• Accession Number: 01368818
• Record Type: Publication
• Report/Paper Numbers: FHWA-AZ-10-605(1)
• Contract Numbers: SPR-PL-1(69)ITEM 605
• Files: NTL, TRIS, USDOT, STATEDOT
• Created Date: Apr 30 2012 7:54AM