The objectives of this study were to update individual vehicle noise data taken in previous years in Kentucky and to determine reference mean energy emission levels for Kentucky vehicles for use in the SNAP 1 noise prediction procedure.

Comparison of Kentucky and nationwide emission levels showed a close agreement for medium and heavy trucks; however, automobile noise levels in Kentucky were higher than nationwide levels. An analysis of emission levels of the various vehicle types showed that a fourth category, light trucks, may need to be added. The Kentucky emission levels were input into SNAP 1 in place of the nationwide levels, but the nationwide values gave closer overall results when compared to measured values. Therefore, it was recommended that the use of nationwide emission levels be continued in the SNAP 1 program until such time as results showing closer agreement between measured and predicted values using the nationwide levels can be explained. It was also recommended that the equations relating emission levels and speed for the four categories of vehicles (automobile, light trucks, medium trucks, heavy trucks) be adopted as representative of emission levels for vehicles in Kentucky.

Noise levels of automobiles and trucks were found to have decreased over the past several years.

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The contents of this report reflect the views of the author who is responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky nor of the Kentucky Department of Transportation. This report does not constitute a standard, specification, or regulation.