Adaptive Cruise Control Systems and Their Influence on Traffic Flow

Adaptive cruise control (ACC) systems are currently being developed by automotive manufacturers for highway vehicle automation [3],[4]. An ACC system enhances regular cruise control by using an on-board radar to maintain a desired spacing from a preceding vehicle that has been detected in the same lane on the highway. The firstgeneration ACC systems are currently available in Japan and Europe and are about to be introduced in the North American market. As this report points out, existing ACC systems have been primarily designed from the perspective of driver comfort. They suffer from several shortcomings when issues of safety and traffic flow are considered. The present project analyzes ACC systems and shows how the development of intelligent algorithms can lead to significant increases in highway capacity and safety, as ACC systems are expected to become standard automotive equipment in the future. The project concentrated on the following specific areas of research : 1) Development of a unified evaluation framework for the evaluation of ACC algorithms, taking into account safety, comfort and time-to-destination of individual vehicles as well as highway utilization and stability of traffic flow. 2) Analysis of existing ACC control systems from the point of view of the above evaluation framework. 3) Development of new vehicle following algorithms that overcome the shortcomings of existing adaptive cruise control algorithms and naturally score highly in the new evaluation framework. 4) Study of the impact of ACC vehicles on highway traffic as a function of their percentage compared to the percentage of manually driven vehicles. Theoretical analysis and micro-simulation traffic tools were both used extensively in the analysis. The Extended Summary in the following pages summarizes the major technical results obtained in the project. Complete details are provided in the attached chapters.