Lateral And Longitudinal Grip Variation

Longitudinal measurement of wet skid resistance is used in many countries to manage the safety of its highway asset. The effect of aggregate type/size, asphalt type / age, degree of trafficking, climate, corners, braking etc. can all be seen in the measured data. However, longitudinal measurement does not show differences in grip across the lane being measured. This paper first considers typical longitudinal variation and then looks at the effect of lateral variation. Simple examples are given for each. The combination of longitudinal and lateral variation is considered in the context of racing circuits. Three case studies explore how GPS based grip data can be plotted using GIS software. The case studies show how the vehicle/tyre interacts with the asphalt surface trying to seek equilibrium conditions.