SELECTED ACOUSTICAL PARAMETERS OF HIGHWAY NOISE BARRIERS

A need existed (a) to determine the influence of selected barrier characteristics on barrier performance and (b) to develop procedures to incorporate these effects in the design process. Thus, the objective of this investigation was to examine the manner in which noise propagates over barriers of different cross-sectional shape (e.g., thin walls, sharp wedges, trapezoids, walls on trapezoids, and round-topped berm-like shapes). An additional objective was to investigate and describe the effect of the terrain cover behind a barrier and the effects of partially absorptive barrier coverings on the net effectiveness of noise abatement behind a barrier. The research aimed at accomplishing these objectives was theoretical in nature, being based on adaptations of previously developed theory and carried out with explicit assumptions about conditions of highway alinement, source characteristics, ground surface, and so on. The models thereby reasonably represent realistic highway noise situations. The project has been highly successful in accomplishing its objectives. As yet, however, and pending follow-on work, the results have only limited applicability in practice. As noted, the effects of the barrier parameters were explored in theoretical terms. A second phase of the project, started in 1978, is expected to validate these findings by scale-model testing and measurement. Even so, the current research results will be of interest in their own right to at least two audiences. For readers who are not acousticians, the report has been designed to communicate some feeling for the impacts of the selected barrier parameters on barrier attenuation and insertion loss. For acoustic specialists, the report seeks to provide tools for modifying design manuals. This latter group will find that the report appendices offer comprehensive details for their consideration. /Author/

Media Info

  • Features: Appendices; Figures;
  • Pagination: 8 p.
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00193479
  • Record Type: Publication
  • Report/Paper Numbers: NCHRP 326
  • Files: TRIS, TRB
  • Created Date: May 26 1979 12:00AM