This paper summarizes the state of the art of research on pavement texture, which has intensified during the last few years. The importance of texture for increased safety on wet roads has been established. The distinct contributions of microtexture and macrotexture to friction between tire and pavement are shown, and methods being developed for providing and maintaining adequate texture are discussed. Research now in progress both on improving methods of texture measurement and on developing models for predicting skid resistance and gradients of skid resistance and speed from texture measurements is described.

Effective pavement texture is essential for safer wet-weather highway travel. The fine features (microtexture) furnish a gritty surface to penetrate the thin water films and produce skid resistance through good adhesion between the tire and pavement surfaces. The coarse features (macrotexture) provide drainage channels for water expulsion between the tire and the roadway. This allows better tire contact with the pavement to improve skid resistance and mitigate hydroplaning (l, l>· It yields a flatter gradient of wet-pavement skid resistance and speed that helps sustain good friction for high-speed traffic, because the water can escape faster through a coarser texture. A knobby or coarse-textured surface also causes larger rubber deformations, which result in hysteresis losses in the tire. These increase the tire friction characteristics. Furthermore, it has been shown that the wet-pavement accident rate decreases as skid resistance increases (1). Thus, effective pavement texture is an important factor _in traffic safety.