"This report will be of interest to state DOT pavement engineers, environmental specialists, and noise analysts. The relationship between pavement surface texture and highway traffic noise is discussed. Information for the synthesis was collected by surveying state transportation agencies and by conducting a literature search of both domestic and foreign publications."--Avant-propos.

Because of the potentially conflicting considerations for cost, durability, environment and safety the design engineer must have information on each such subject on which to base his decisions. The great variety of pavement textures for affecting the noise levels generated by traffic on the highway, made the need for information on the effect of pavement texture on tire road noise obvious. Noise measurements were made at 19 sites, including both bituminous (I-2, S-5, S-8 surface treatment) and portland cement concrete (aggregate exposed and grooved) pavements that had a wide variety of textures. A 1971 Plymouth 4-door sedan was used as the test vehicle. Both rib treads and snow treads were used in the tests. The data were analyzed in the linear (dB) and A-weighted (dBA) modes. Frequency analyses were made on ten recordings that were representative of most of the data. It was determined that pavement parameters such as density, type of aggregate, and the flat-mosaic aspect had very little effect on the intensity of the noise generated. The parameter that had the greatest effect was the degree of protuberance. From the analyses of the frequency content of the noise it was determined that the 3/4 inch (1.9 cm) transverse grooved and the dimpled textures generated relatively pure tones in the high frequency range most easily sensed by humans. Recommendations are made concerning the use of the various pavement surfaces tested.

Traffic noise mitigation strategies are developed by considering the source, path, and receiver of the noise. Within the United States, strategies involving the path of traffic noise have dominated noise abatement efforts on Federal and State levels. As a result, many miles of barriers have been constructed to shield affected receivers from traffic noise. Strategies aimed at reducing the source of traffic noise are appealing in light of the potential for reducing these abatement costs. Vehicle noise has been divided into six noise-producing components: engine, fan, intake, exhaust, drive train, and tires. Due to market forces, vehicle manufacturers have been motivated in recent years to reduce the noise generated by these components. As progress has been made by manufacturers to reduce the noise emitted by the various sub-sources within motor vehicles, tire/road noise has emerged as the dominant component of traffic noise for speeds greater than 35-40 mph. Recent European studies have concluded that tire/road noise levels vary substantially according to pavement type [Herman and Bowlby 1993].

This report contains guidelines and recommendations for managing and designing for friction on highway pavements. The contents of this report will be of interest to highway materials, construction, pavement management, safety, design, and research engineers, as well as others concerned with the friction and related surface characteristics of highway pavements.