Noise Level Reduction of “Depressed” Freeways

The paper describes a method of determining the sound level reduction afforded by “depressed” roadways, i.e., traffic lanes which are located below the general elevation of adjacent residential or industrial areas. It is based on the well-known optical case of light passing a knife edge and causing a diffraction pattern or a light shadow to exist below the edge. Various means are discussed to increase the sound level reduction, as by partially closing in the roadway, erecting a barrier near its edge, slanting the roadway banks to achieve a desirable deflection of the noise “rays,” or combinations of these means.

Print ISSN

0361-4573

Published

1960-02

Content type

Original Research

DOI

10.5594/J14421