Evaluation of driving performance after a transition from automated to manual control: a driving simulator study

Nowadays, automated driving is one of the most discussed topic in transportation research community and media. Although several studies demonstrated how automated driving could improve road safety and operations, other evidences underscore the emerging nature of this technology and suggest that still much more research is needed before widespread benefits can be realized. One concern is surely related to the understanding if an automation period can reduce fatigue and/or distract drivers, especially when they have been inattentive and involved in a secondary task during highly automated driving. The aim of this study is to assess the driver behaviour after resuming control from a highly automated vehicle. A driving simulator study was designed and forty-three participants drove twice a highway scenario. One drive was without automation, just manual control of the vehicle (FM). In the other drive, the automation was activated in the first half of the scenario and the drivers were asked to watch a movie inside the vehicle; then they resumed control from the automation and drove manually the second half of the scenario (AM). In both the manual control drives, several expected (car following and passing) and unexpected (sudden brake of leading vehicle) events occurred. Several driving performance were collected, analysed and compared between the two scenarios for each event. Moreover, subjective measures were also collected by means of NASA-TLX questionnaire to evaluate the workload perceived while driving. The results show not significant after-effects of the automation on driving performance although a more dangerous behaviour of drivers who previously had a driving automation period was noted in some cases.