Reliability-Based Risk Analysis of Roadway Horizontal Curves

Abstract

Reliability-based analysis of road geometric design has been reported in literatures as a trend in transportation safety study. In the reliability analysis of a horizontal curve, the performance function is usually formulated as a function of the failure mode of vehicle skidding only. This paper takes into account the failure modes of vehicle skidding and rollover in formulating the performance functions of cars and trucks, respectively. A comparative study of three different performance functions for calculating the probability of vehicle failure modes is conducted. The results qualitatively show that trucks are more vulnerable to skid than cars, and are more likely to rollover than to skid on dry pavement. A vehicle's is greatly influenced by vehicle suspension and roll motion. A sensitivity analysis investigating the influences of vehicle parameters and superelevation on vehicle skidding and rollover follows. In order to make the paper practically useful, the probability of failure for the minimum radius recommended by AASHTO at various superelevations and design speeds was computed to investigate the reliability of the recommended minimum radius.