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.