Mapping Heavy Vehicle Noise Source Heights for Highway Noise Analysis

This research seeks to determine the height distributions and spectral content for heavy trucks. With the use of acoustic beamforming technology, the noise source regions for 1,289 heavy trucks were mapped during vehicle pass-bys on public highways at 20 different measurement sites in two different states. These acoustical source maps indicated that tire/pavement noise at ground level was the predominant source, with engine-related noise being a secondary source. Tire/pavement noise typically split equally between the drive axle tires and the trailer tires. From the source maps, vertical profiles of noise versus height were calculated. The profiles were found to be essentially independent of vehicle speed, pavement, operating conditions, and region, even though the statistical isolated pass-by (SIP) levels were dependent on these parameters. The average of the vertical profiles was used to explore simpler source distributions that could be used in traffic noise modeling. The researchers found that a two-point source distribution could adequately represent the profile and yield similar barrier insertion loss values. One source needed to be located at ground level for all frequency bands, which is the same as that used in the FHWA Transportation Noise Model (TNM®). The upper source height of 12 ft used in TNM was not found to be viable in attempting to match the average heavy truck profile. To match the profile, the upper source height was 3.3ft at low frequency and 1ft at high frequency, with heights of 2.3 and 1.6ft used for frequency bands in between. Barrier insertion loss using the TNM distribution was also found to be less than that calculated for the average truck profile. This research also expands the database of heavy truck pass-by levels for use in future modeling. To accomplish this, the levels of each truck pass-by were captured at each site in addition to beamforming measurements for comparison with the FHWA Reference Energy Mean Emission Levels (REMELs) database from 1994. Above about 50 miles per hour (mph), the levels from this research determined a regression curve matched the REMELs quite well for both cruise and interrupted/grade conditions. Below 50 mph, the pass-by results were about 2 to 5 dB lower than the REMELs for interrupted/grade conditions. These results indicated that, although the levels for higher speeds are adequately represented by the current database, additional data for lower speed conditions is needed.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 94p
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 01628088
  • Record Type: Publication
  • ISBN: 9780309446181
  • Report/Paper Numbers: Project 25-45
  • Files: TRIS, TRB, ATRI
  • Created Date: Mar 7 2017 9:06AM