Abstract
The results of research conducted by north central technical college and cosponsored by ohio's thomas edison program and empire-detroit steel division are reported. Laboratory and full-scale outdoor testing of both reflective and absorptive highway noise barriers are discussed. The phenomena of single-barrier insertion loss degradation caused by the addition of a second parallel barrier was confirmed.Further, absorptive barriers evidenced performance benefits over reflective barriers in parallel tests. Single-barrier insertion loss tests supported barrier attenuation theory for the configurations tested. This paper appears in transportation research record no. 1312, Energy and environmental issues 1991.