The basic components of noise prediction methods are examined, areas of deficiency are noted and methods of improvement are considered. Equations representing the time-averaged overall sound pressure level developed in 1952 are presented, and later developments in 1968 (Johnson and Saunders) are outlined. Also reported in 1968 were Galloway's model which simulated a static array of vehicles distributed randomly along a roadway and summed their noise levels at specified points off the roadway. The National Cooperative Research Program (NCHRP) method 117 is the most widely used prediction method. The TSC method published in 1972 provides a computerized highway noise prediction method. Like the NCHRP 117, it calculates light-vehicle and heavy-vehicle noise levels separately and sums them to obtain the total noise. The TSC method also includes a third class of vehicles for which the octave band spectrum can be specified and the resultant noise added to the levels calcualted for light vehicles and heavy vehicles. Also in 1972, Delany published a model for calculating L10 levels from highway traffic noise. The NCHRP 117 (with subsequent revisions of NCHRP 144), TSC and Delany procedures include provisions for calculating the effects of barriers in the vicinity of the highways under study. The comparison of results using the NCHRP 117 and TSC procedures, indicate no logical pattern.

Media Info

  • Features: Figures; References;
  • Pagination: p. 9-13
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00131393
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: May 14 1976 12:00AM