The progress in developing highly automated driving applications and the corresponding opportunities for the driver to take himself out of the loop have raised a couple of questions regarding the effects of highly automated driving on the driver's state. Within this framework a simulator study was conducted at the Wuerzburg Institute for Traffic Sciences (WIVW GmbH) in collaboration with Volkswagen Group Research with 16 test drivers. The drivers took part in three sessions each requiring him/her to drive on a highway with a speed limit of 120 km/h. Drowsiness was assessed continuously during the drive by eye lid closure measurements and was classified into 4 different levels. Whenever a driver reached a certain drowsiness level during the manual drive, a test phase of 15 minutes was initiated ending with a take-over scenario. Depending on the experimental condition, the test phase was 1) driving with a highly automated system (lateral and longitudinal control was performed by the automated system allowing hands-off driving), 2) driving with the system and additionally performing a quiz task or 3) driving manually during the test phase. The results show that especially in the manual and the highly automated condition without secondary task engagement the drowsiness level clearly increased during the 15 minutes test phases. During the phases with highly automated system active and the additional quiz task, drowsiness stayed on a low level and remained constant during the test phase. This implicates that an interesting and motivating secondary task has the potential to raise driver's alertness significantly, especially during highly automated driving.
Schömig, N., Hargutt, V., Neukum, A., Petermann-Stock, I., & Othersen, I. (2015). The Interaction Between Highly Automated Driving and the Development of Drowsiness. Procedia Manufacturing, 3, 6652–6659. https://doi.org/10.1016/j.promfg.2015.11.005