Pavement Friction and Texture Performance Modeling

Abstract: When a tire rolls over a pavement there will be different interaction components depending on the amount of deformation and the properties of the contact interface. In the literature it is reported that the skid resistance available in the tire-pavement interface depends on two main mechanisms, adhesion and hysteresis. The first is related to the aggregate mineralogy and shape, whereas the second is proportional to the energy loss resulting from the tire deformation caused by the texture profile. There is evidence that there is often an increase in the wet crash rates after placement of new asphalt wearing courses. An initial decrease in friction and texture after placement of the new surface has been reported as one contributing factor to observed increases in wet crash rates. Therefore, it is of interest to derive a set of expressions that can be used to predict the available long-term friction and texture performance. To this end, this research used more than 200 different pavements, with different ages, traffic levels, and climatic conditions to propose a general functional form for the friction and texture performance models. These models were calibrated using continuous friction measurements and high-speed texture observations. To account for the random pavement performance variation, a random effect model structure was selected. The calibrated expressions indicated that to get accurate predictions of friction and texture performance it is necessary to include random effects in the performance curve. Texture performance models had higher accuracy than the friction models, because overall the mean profile depth (MPD) have a more stable variation between measurements, whereas friction is more susceptible to higher source of variations like temperature changes and amount of precipitation. The model validation showed the proposed performance models can capture individual performance variation trends. The random effect in the intercept seems to capture a big portion of the pavement performance variation trend at each pavement; but the validation procedure showed that the friction and texture rate of change for some pavements deviate from that of the family. In the long-term, friction seems to be reducing based on the cumulative effect of traffic repetitions that cause aggregate polishing. However, as observed in some sites, friction might increase in presence of moderate to severe raveling process, typical of old surfaces.