Urban light motor vehicle noise levels at close‐in distances for a worst case situation

Abstract

Effective motor vehicle noise enforcement in many urban areas can only be accomplished if measurements are made relatively close to the vehicle. To help define reasonable enforcement levels, in situ sound level measurements were recorded in four geographical locations for 8307 light weight motor vehicles accelerating from rest or near rest. To insure a “worst case” situation, the microphones were positioned at 3.81 m from the centerline of travel and 27 to 46 m from the initial point of acceleration. The data were partitioned into three “acceptable” vehicle classes and one class which included all vehicles judged to have had defective or modified exhaust systems, or had been unreasonably driven. Analysis of the data shows that the “unacceptable” vehicle distribution has a mean sound level at least 6 dBA greater than those obtained for all of the “acceptable” classes. Relations between the posted speed limits and the mean values of the observed sound levels were obtained.