Understanding Driver's Situation Awareness in Highly Automated Driving

This study investigated the influence of road complexity and lead time on driver's situation awareness with three consecutive experiments. 7 participants were asked to watch simulated and real-world driving videos and answer their situation awareness level by SAGAT, SART, and subjective measures. In the first experiment, the effects of road complexity and lead time on the situation awareness level was tested. We found that driver's situation awareness is influenced by road complexity, but lead time had minimal effects. In the second and third experiment, we investigate the effects of traffic density and road type based on the simulated and real-world stimuli. The traffic density affects driver's situation awareness, while the road type did not. This effect was also reproduced in real-world stimuli. In addition, we could find an interesting trend in which people seem to adjust their desired situation awareness level according to the driving contexts.