Rutting is a major form of pavement distress in asphalt pavements. The main concern with rutting has been related to driving safety. Many highway agencies and researchers suggested that pavement rutting could lead to vehicle hydroplaning and loss of skid resistance in wet weather. However, to date no theoretical basis has been established for an analytical assessment of the severity of rutting for the purpose of pavement maintenance and rehabilitation. Most highway agencies classify rut severity on the basis of engineering judgment or field experience. This paper presents an analytical procedure to assess the severity of rutting based on vehicle skidding and hydroplaning analysis. It considers the worst-case scenario where a rut is filled with water and analyzes (1) if a car will hydroplane at a given speed; and (2) the length of braking distance required for the car traveling at the given speed. A finite-element simulation model is adopted to perform the analysis. For a given rut depth filled with water, the computer model computes the hydroplaning speed for a typical passenger car, and the required braking distance for the car traveling at a known speed. It was found that depending on the rut depth and the surface frictional property of a pavement, the severity classification of a rut may be governed by either hydroplaning risk or safety requirement of braking distance. The traditional method of using the same set of critical rut depths for all pavement sections in a road network is not ideal for effective handling of rutting maintenance.

The risk of hydroplaning and reduction of skid resistance are two major safety concerns in wet weathering traffic operations on highways and runways. The writers earlier developed an analytical computer model to simulate the phenomenon of hydroplaning. The simulation of wet-pavement skid resistance is analytically a more complex problem to handle than hydroplaning simulation. The present paper adopts a more elaborate theoretical approach and proposes an improved analytical computer model to simulate hydroplaning as well as the reduction of wet-pavement skid resistance as the sliding wheel speed increases. The theoretical formulation and development of a three-dimensional finite-element model based on solid mechanics and fluid dynamics is presented. The computed hydroplaning speeds by the proposed model were analyzed and verified against the well-known experimentally derived NASA hydroplaning-speed equation. The analysis confirmed that the NASA equation is a special case of a general solution, and that it ...

This paper presents a numerical simulation of the wet-pavement skid resistance reduction process as the sliding speed of a locked wheel increases. The development of the three-dimensional finite-element model used for the simulation is presented in a companion paper. The proposed model is able to simulate tire-fluid-pavement interaction of a sliding locked wheel on a wet pavement for hydroplaning and skid resistance analysis. The verification of its ability to predict hydroplaning speed is found in the companion paper. In this paper, the validation of the predicted wet pavement skid resistance at different sliding wheel speeds is made by comparing it with measured values from six different experiments conducted by past researchers. A very good match is found between the computed values by the proposed numerical model and the measured data. The analytical model offers a useful tool to predict the magnitude of wet-pavement skid resistance at any given locked-wheel sliding speed. As an analytical model, it a...