The contribution of micro- and macro-texture to the skid resistance of flexible pavement.

Skid resistance is an important characteristic of the pavement surface to reduce the number of road accidents. The mechanisms involved in the activation of the frictional force required for a safe braking of the vehicle depend on both the macro- and the micro-texture of the pavement surface. The state-of-the-practice methodologies commonly used for measuring pavement texture at highway speeds only account for the macro-texture, which alone might not be sufficient to effectively characterize skid resistance. This study explored different ways to characterize the micro-texture of pavement surfaces with the main objective of quantifying the effect of accounting for both the micro and the macro components of the texture, rather than just the macro-texture, on the prediction of skid resistance. The friction and texture data analyzed in this study were collected from an experiment conducted on in-service flexible pavement surfaces. Surface friction was measured using a British Pendulum Tester whereas texture data was collected using a Circular Track Meter and a Laser Texture Scanner. The surface micro-texture was characterized by different texture parameters calculated in both the spectral and the spatial domain. The impact of incorporating the micro-texture on the prediction of skid resistance was evaluated by analyzing a series of models specified by each of the proposed parameters. The results of the analyses show a significant improvement in predicting the surface friction when accounting for both components of the surface texture, as opposed to only the macro-texture. Furthermore, the parameters calculated on the frequency domain led to a better prediction power.