Modeling Free-Flow Speed Considering Water Depth under Ponding Conditions: A Dynamic Method from the Viewpoint of Hydroplaning

This paper proposes a method for evaluating free flow speed from the viewpoint of hydroplaning using dynamics method. First, the reduction of tire-road friction coefficient caused by speed and water depth is physically calculated by analyzing the reduction of the wheel load. The next step is to analyze the resistances under the accumulated water environment and the condition of sliding under these circumstances in order to calculate the bounded velocity at which slippage occurs. The observations data obtained in Japan, 2009 are compared with the physical computing slippage occurrence velocity and yield the conclusion that tractive force equivalent to the measured desired speed is 20.7%, equivalent to the slippage occurrence speed. Moreover, an adequate replication of free flow speed according to different water depth is yielded.