California Partners for Advanced Transportation Technology

In Automated Highway Systems (AHS), vehicles are equipped with automatic control systems to govern the accelerating, steering and braking functions in order to maintain an appropriate speed and spacing with respect to the surrounding vehicles. One concept of AHS suggests the implementation of vehicle platoons with small spacing between vehicles. With vehicles moving closely together in platoons, the hazards of "chain-reaction" collisions become a concern. The benefits of small delta-V need to be weighed against the number of collisions in such feared "chain-collision" scenarios. This report discusses the effects of collisions in vehicle-following operations, especially for short-spacing scenarios. In this study, the collision analysis is conducted with a two-dimensional simulation program by which the translational and rotational movements of vehicles can be fully represented. For example, a greater delta-V of the initial collisions or a larger lateral offset between the vehicles can cause the greatest deviations from the specified path. Also presented in this report are simulation scenarios where control actions are taken in post- impact conditions. Vehicle maneuvers in these simulations include steering and braking inputs to perform lane-following and lane changing. The potential implications and the effects of these maneuvers on the vehicle trajectories are discussed. The studies of these post-impact maneuvers offer a perspective on the possible actions for vehicles in automated modes. The current and future work of this study should provide insights for the evaluation of the safety hazards and control strategies in AHS. KEY WORDS Automated Highway Systems (AHS), Advanced Vehicle Control Systems (AVCS), Vehicle Collision, Simulation.