California Partners for Advanced Transportation Technology

This paper develops a probabilistic model and a software tool for analyzing longitudinal collision/safety between two automated vehicles. The input parameters are the length of the gap between the two vehicles, the common speed prior to failure, the reaction delay of the following vehicle and a bivariate joint distribution of the deceleration rates of the two vehicles. The output includes the probability of a collision and also the probability distribution of the relative speed at collision time. The model is used to compare the safety consequences associated with the platooning and "free-agent" vehicle-following rules. Additionally, it is demonstrated that the free-agent vehicle-following rule implemented with a potential technology of fast and accurate emergency deceleration, under some reasonable conditions, can virtually avoid collisions while offering a high freeway capacity previously through possible only under the platooning rule.