Required Passing Sight Distance for Rural Roads: A Risk Analysis

This paper reports on the development of a model that describes the kinematics of vehicle trajectories during the passing (overtaking) maneuver on two-lane, two-way rural roads and highways. The authors used the model to determine the total required sight distance. They used a Monte Carlo computer simulation to conduct a risk assessment analysis. Results showed that the acceleration characteristics of the passing vehicle may not have a significant effect on required passing sight distance. The authors conclude that further research into the actual behavior of drivers performing passing maneuvers is required in order to develop appropriate required passing sight distance standards. They caution that the current methods used by many roading authorities worldwide (safe passing distances are determined by simplistic kinematic formulation) may be inadequate.