FIELD EVALUATION OF ACOUSTICAL PERFORMANCE OF PARALLEL HIGHWAY NOISE BARRIERS ALONG ROUTE 99 IN SACRAMENTO, CALIFORNIA. FINAL REPORT

The effects of multiple reflections between two parallel highway noise barriers on the acoustical performance of each of the barriers have been a subject of considerable controversy. Mathematical and scale modeling predict possible large reductions (degradations) in the effectiveness of noise barriers with smooth, hard surfaces (such as masonry or concrete) due to parallel configurations. However, noise measurements under conditions of actual highway traffic, typical barrier heights and separations have yet to confirm the large degradations. This report presents the methods and results of a parallel noise barrier research project performed by the California Department of Transportation (Caltrans). Field measurements of noise, traffic, and meteorology were made in three stages: before barrier construction, after construction of the near barrier, and after construction of the barrier on the opposite side of a highway. The selected site was typical of many parallel barrier configurations in California. More than 100 simultaneous, A-weighted, 15-minute energy-averaged noise levels were measured at 11 microphones located at heights ranging from 5 to 23 feet, and distances of 15 to 200 feet behind the near barrier. The noise data were matched by crosswind vector wind velocities and normalized for differences in traffic. Analysis results showed degradations of 0 to 1.9 dBA, independent of wind. Vector wind velocities of -3 to +11 mph caused variations in noise levels of up to 9 dBA, at 200 feet behind the near barrier.

• Corporate Authors:

  California Department of Transportation

  Transportation Laboratory
  5900 Folsom Boulevard
  Sacramento, CA  United States  95819

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Hendriks, R W
• Publication Date: 1991-1

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: v.p.

Subject/Index Terms

• TRT Terms: Acoustic properties; Before and after studies; Field tests; Noise barriers; Performance; Sound level; Velocity; Wind
• Uncontrolled Terms: Degradation; Field measurements
• Old TRIS Terms: Parallel configuration; Wind velocity
• Subject Areas: Design; Environment; Highways; Planning and Forecasting; I21: Planning of Transport Infrastructure;

Filing Info

• Accession Number: 00610153
• Record Type: Publication
• Report/Paper Numbers: FHWA/CA/TL-91/01, 65328-637370
• Contract Numbers: E89TL08
• Files: TRIS, USDOT, STATEDOT
• Created Date: Jun 30 1991 12:00AM