Water accumulation and anti-sliding decay characteristics of freeway pavement at superelevation transitions

To evaluate the water accumulation status at superelevation transitions of the freeway and establish a correlation with wet friction, laboratory tests and theoretical calculation approaches were carried out during water-film formation and sheet flow stages. The influencing factors on water depth and the water depth dependency of friction were analyzed using the self-developed multi-directional adjustment tester. The results indicate that the ponding is severe at flat road sections, adjusting alignment and improving drainage capacity are the key remedies. There is a good correlation between decay characteristics of dynamic friction and the water depth. The wet grip can be explained by the tribology principle and lubrication regimes, which is decomposed into the distinct contributions of tire, pavement, and water. Besides, the water depth threshold was determined. Finally, a prediction model of water depth at superelevation transitions was established based on the hydromechanics analysis. It shows significant correlations with the Gallaway model.