California Partners for Advanced Transportation Technology

Cooperative Adaptive Cruise Control (CACC) is a term that has been used rather loosely in recent years, such that different people visualize different functions and capabilities when discussing CACC systems. Thus, there are now multiple system concepts that have been described under the CACC label, and the functionalities included in these varied concepts can be quite different from each other. At the heart of each CACC concept is the merging of Adaptive Cruise Control (ACC), a subset of the broader class of automated speed control systems, with acooperative element, such a Vehicle-to-Vehicle (V2V) or Infrastructure-to-Vehicle (I2V) communication. The V2V communication could provide information about the vehicle or vehicles directly in front of you, and the I2V communication could provide information about traffic further ahead or about current speed restrictions as part of an active traffic management approach.There are two primary transportation system motivations for the development of CACC. The first motivation is to reduce traffic congestion and the second is to improve fuel efficiency. It may also improve safety, although it is not primarily a safety system. At the individual driver level, CACC can make ACC more attractive and convenient to drivers by providing behavior that is more responsive to preceding vehicle speed changes, that gives an enhanced sense of safety because of its quicker response, and that deters cut-ins at shorter gaps.