Identifying Friction Variations with the Standard Smooth Tire for Network Pavement Inventory Friction Testing

Abstract

Because of the evident advantages associated with the smooth tire for the measurement of pavement friction, many highway agencies have become interested in the smooth tire. Pavement friction is the result of tire–pavement interaction. Because of the differences between ribbed and smooth tires, experiences with the ribbed tire may not apply to the smooth tire. Therefore, it is of great importance to evaluate those issues associated with the use of the smooth tire in network pavement inventory friction testing, such as variations in the friction testing system, seasonal friction variations, spatial friction variations, and temporal friction variations. The Indiana Department of Transportation (InDOT) has been using the smooth tire in the network pavement inventory friction test program since 1996. Large amounts of friction data have been obtained in the InDOT friction test track and network pavements. This paper presents the variations in the friction measurements obtained with the smooth tire because of testing system errors and seasonal and temperature effects. The paper also presents the spatial and temporal variations in the friction measurements. It was thought that the results provided in this paper would be useful for highway agencies for determination of test cycle, test spacing, and friction corrections for their network pavement inventory friction testing programs.