Switching from manual to automated driving and reverse: Are drivers behaving more risky after highly automated driving?

Enabling highly automated driving is a long lasting endeavor in traffic research. Whereas technical solutions have been tested for more than 20 years, psychological effects of highly automated driving became subject to debate in the last decade. Recent studies revealed that switching from highly automated to manual driving mode produces some difficulties for drivers. Therefore, the present driving simulator study investigates drivers´ performance before (pre-automation) and after (post-automation) highly automated convoy driving (platooning). Hence it represents a more fine granulated analysis of a simulator experiment from Skottke et al. [1]. The pre-/post-comparison of driver performance shows whether driving behavior is more risky after 33km (20 min.) of highly automated driving in a platoon with a time headway of 0.3 sec.. Results showed that drivers significantly decreased their distance to the lead vehicle in the post-automation driving period compared to their pre-automation duration. Moreover, lateral vehicle control and driving speed differed between pre- and post-automation periods as well. Based on these findings, it can be concluded that highly automated driving critically affects drivers´ post-automation behavior. Consequences for subsequent empirical research and technological developments are discussed.