Incorporating Pavement Skid Resistance and Hydroplaning Risk Considerations in Asphalt Mix Design

An analytical framework and procedure is proposed in this paper to incorporate pavement skid resistance requirements in asphalt mix design, as part of the overall asphalt pavement design process. The concept is introduced with the aim to overcome the inadequacy of current pavement design procedures, asphalt mix design in particular, in addressing pavement-related highway functional safety requirements. Central to the concept is the use of a theoretically derived finite-element simulation model to generate the skid resistance performance curve (i.e.,skid resistance-speed relationship for a given water film thickness) of a pavement surface mix design, based on the input of two skid resistance values measured at different test speeds. Three highway functional safety requirements are addressed, namely the minimum safe terminal skid resistance, the maximum braking distance allowed, and the minimum hydroplaning speed. The proposed framework comprises three main components: (1)a laboratory-accelerated wear and polishing testing of a trial asphalt mix design; (2)estimation of in-service pavement skid resistance from laboratory friction measurements in the component from Step 1; and (3)an analytical simulation component that uses the finite-element model to derive the skid resistance and hydroplaning performance of the mix design, and checks for compliance with the three functional safety requirements. A numerical example is presented to demonstrate the steps involved and data required in the application of the proposed procedure. It is believed that the work presented offers a useful step forward toward bridging the gap between pavement design and functional requirements of highways.