Adaptive cruise control (ACC) systems incorporate a distance-keeping function in addition to the speed regulation provided by conventional cruise control. This is achieved by calculating an appropriate time headway to a leading vehicle and using this to over-ride a chosen speed setting if the relative speeds of the two vehicles are such that the following vehicle is too close to the leading vehicle. Responsibility for headway maintenance remains with the driver. The stop and start driving pattern of urban traffic was simulated with light and heavy traffic densities and the use of the ACC system tested with young and old drivers. An emergency reaction test was incorporated into the study on the driving simulator. Mean speeds were higher but more variable when driving in light traffic and ACC increased the variability. Participants drove closer to the lead vehicle when driving with ACC in comparison with normal driving. Significantly more instances where the driver took control of the ACC by braking were observed in heavy than in light traffic. These instances occurred even though the drivers had been told ACC would not fail. Driver reaction times did not differ with age or traffic density. ACC reduced mental workload. Participants found the ACC easy to use but considered it reduced the pleasure of driving. 31% of test users were not prepared to buy the system while nearly 25% were prepared to pay £60-£310. Both young and old drivers adapted to the ACC system but older drivers were less comfortable with the system. For the covering abstract see ITRD E118297.
Abstract