Abstract
The aim of this stydy was to investigate driver behavior when resuming control from a lower level of automated driving system. Fourteen drivers participated in a driving simulator experiment to investigate the aim. The driver’s vehicle could automatically adjust a headway distance to a lead vehicle and keep its lateral position in a lane. After automated driving for about twenty-five minutes, the lead vehicle unexpectedly slowed down and the driver’s vehicle could not adjust the headway distance automatically. Drivers had to step on the brake pedal to avoid collision with the lead vehicle. Both visual display and auditory tone were given to drivers to signal limited automated driving. The results of the driving simulator experiment showed that many drivers were unable to react to the limited automated driving appropriately, and the risk of the collision with the lead vehicle increased because it was difficult for drivers to notice both visual and auditory displays. the findings suggest that it is important to design both visual and auditory displays so that drivers could notice the limited automated driving.
