Adaptive cruise control - what can the network operator expect?

Mercedes launched the first European Adaptive Cruise Control (ACC) system in the new S-Class model at the end of 1998. Since the PROMETHEUS program of research there have been a number of studies in Europe investigating the potential impact of ACC on network efficiency, safety, the environment and driver behaviour. The studies have involved field trials, microscopic traffic simulation and simulator studies. This paper draws together the results from these studies and presents a new approach to examining ACC. The study shows that ACC has limited operating capabilities in peak traffic but will provide substantial environmental improvements outside of these periods. The paper begins with a state-of-art review of the current understanding of ACC from studies in Europe, USA and Japan. A description of a data collection exercise using an Instrumented Vehicle measuring real driver following behaviour at four sites across Europe is then presented. Microscopic simulation is used to determine the change in following behaviour that would ensue if the following vehicle had been equipped with an ACC system. A discussion follows on the traffic conditions that will provide the operating boundaries for ACC and the potential for ACC to modify current network capacity. The paper concludes by examining the potential interactions between ACC equipped vehicles and current fixed infrastructure telematics applications such as variable speed limits.The paper is based on work carried out within the 'Deployment of Inter-Urban ATT Test Scenarios' (DIATS) DGVII funded Fourth Framework projec