Document Type


Publication Date

June 1993

Publication Title

PATH Working Paper


AVCS, Collision Speed Distribution, Platooning, Free-Agent


Industrial Engineering | Operations Research, Systems Engineering and Industrial Engineering | Systems Engineering


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 the failure, the reaction delay of the following vehicle and a bivariate pint 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.We will use this model to compare the safety consequences associated with the platooning and "free-agent" vehicle-following rules. We will also demonstrate 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 thought possible only under the platooning rule.


This work was performed as part of the California PATH Program of the University of California, in cooperation with the State of California Business, Transportation, and Housing Agency, Department of Transportation; and the United States Department Transportation, Federal Highway Administration.The contents of this report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the State of California. This report does not constitute a standard, specification, or regulation.This report is also available at this link.