Analysis of skidding potential and safe vehicle speeds on wet horizontal pavement curves

Abstract

Skidding on wet horizontal pavement curves is a major traffic safety concern. Themaximum safe driving speed against skidding is an important threshold for safe driving. However, because of the complex tire-pavement-fluid interaction mechanism and the large number of variables involved (including curve geometric parameters, pavement surface properties, properties of tire in motion, and water film thickness), currently there is no practical working procedure that allows pavement engineers to determine the maximum safe driving speed on a horizontal curve under a given wet weather condition. This paper presents a finite element model to predict the maximum safe driving speed on a wet curved roadway section based on solid mechanics and hydrodynamics. The numerical simulation model was developed and validated against experimental skid resistance values on slip angles from 0° to 90°. Based on skidding analysis, the maximum safe driving speed on a horizontal curve is derived by comparing the available tire-pavement frictional resistance and the required friction to prevent skidding caused by the centrifugal force of the vehicle concerned. An illustrative case study is presented to compare the calculated maximum safe vehicle speed with AASHTO design speed. The analysis presented suggested that the proposed approach offers a useful tool to calculate maximum safe speeds on in-service pavement curves for safe driving.