The Effect of Automated Driving Levels and Road Type on Driver’s Performances in Secondary Tasks and Situation Awareness

In this driving simulation study, the effect of different levels of vehicle control requirement manipulated by three levels of automated (fully automated driving condition where no vehicle control is required, partially automated driving condition requiring only lateral control of the vehicle, and fully manual driving condition requiring both longitudinal and lateral control) and the road type (straight road, curved road) on the performances of secondary tasks (arrow direction detection task, working memory search task) and situation awareness task were investigated. The main results of this study are summarized as follows. First, the detection time for the arrow stimulus direction, the search time for information retained in working memory, the response accuracy in the search, and the situation awareness all showed relatively better performance as the level of automated driving increased and under the straight road condition rather than under the curved road condition. Second, in the fully automated driving condition, the arrow direction detection time and situation awareness scores did not show significant differences between the road type condition. The results of this study suggest that as the level of automated driving increases, and thus the level of load for vehicle control decreases, the driver's workload may decrease while situation awareness may increase.