Investigation of Driver Behavior During Minimal Risk Maneuvers of Automated Vehicles

Minimal Risk Maneuvers (MRMs) are introduced to reduce the risk of an accident during the transition from automated to manual driving. In this paper, we present the results of a dynamic driving simulator study with 56 participants with the control authority as the independent variable, i.e. allowing and blocking driver input during the MRM. In order to not communicate wrong information, input blocking was established by disabling the brake and gas pedal but not the steering wheel. The latter turned according to the performed MRM and participants had to overcome high counterforces to change the vehicle’s direction. Two scenarios on a highway were investigated with the ego vehicle located in the right lane and only differing in the implemented MRM, i.e. stopping in the own lane or maneuvering to the shoulder lane combined with a standstill. Our results show a high intervention rate in both groups. Participants intervened mainly by maneuvering into the middle lane and after the Human-Machine-Interface announced the upcoming maneuver. In total, four accidents and five dangerous situations occurred due to interventions in both groups. Trajectories during re-entering into traffic showed that participants favored the middle lane over the shoulder lane here as well. To conclude, allowing or blocking driver intervention did not reduce the risk of an accident and more countermeasures need to be taken.