Hydroplaning speed and infrastructure characteristics

This article exposes some results of a study, which aims at modelling the hydroplaning phenomenon taking into account the infrastructural characteristics, the water-depth on the road, the load transfer between the rear and the front wheels, and the skid resistance before total hydroplaning. First, a short bibliographical study determined the most relevant parameters that should be included in a global hydroplaning model such as the tyres' characteristics (pressure, contact area, and tread depth), the load, the water-depth, the road profile, and macrotexture. Among them, the water-depth is the most difficult to evaluate, because it deeply depends on the pavement irregularities (roughness and texture), the road geometry, and the weather (rainfall intensity). Thus, a model calculating the water-film thickness by using road characteristics measurements is proposed. This initial water-depth is included in a linear model with 2 degrees of freedom, which describes the longitudinal dynamics phenomenon. The load transfer between the front and the rear axles is calculated in a straight line. Moreover, the water-depth in front of the rear tyre is calculated by considering the water displacement generated by the front tyres. Then, the increase of the water thickness just in front of the tyre due to the flow in the tyre treads and the pavement macrotexture is modelled. Finally, this model provides a hydroplaning speed, which is used for warning the drivers.