Drivers´ Adaptation to Adaptive Cruise Control: Examination of Automatic and Manual Braking

Drivers may adapt to the automatic braking control feature available on adaptive cruise control (ACC) in ways unintended by designers. This study examines drivers´ adaptation using a conceptual model of adaptive behavior developed and examined quantitatively using logistic regression techniques. Data for this model come from a field operational test on the use of an advanced collision avoidance system, which integrated forward collision warning and ACC functions. A sample of “closing” events was extracted from a subset of these ACC data. The logistic regression model predicted the drivers´ likelihood to intervene (i.e., manually brake) whenever ACC began braking or slowing down the vehicle. The results indicate that several factors influence drivers´ response, including the environment, selected gap setting, speed, and drivers´ age. Safety consequences and the design of future ACC systems based on drivers´ adaptation to these factors are discussed.