I Care Who and Where You Are – Influence of Type, Position and Quantity of Oncoming Vehicles on Perceived Safety During Automated Driving on Rural Roads

There is not yet sufficient knowledge on how people want to be driven in a highly automated vehicle. Currently, trajectory behaviour as one part of the driving style is mostly implemented as a lane-centric position of the vehicle in the lane, but drivers show quite different preferences, especially with oncoming traffic. A driving simulator study was conducted to investigate seemingly natural reactive driving trajectories on rural roads in an oncoming traffic scenario to better understand people’s preferences regarding driving styles. 30 subjects experienced a static and a reactive (based on manual driving) trajectory behaviour on the most common lane widths in Germany: 2.75 m and 3.00 m. There were twelve oncoming traffic scenarios with vehicle variations in type (trucks or cars), quantity (one or two in a row) and position (with or without lateral offset to the road centre) in balanced order. Results show that reactive trajectory behaviour and wider lane widths lead to significantly higher perceived safety. We also identified quantity, type and position of oncoming vehicles as factors that influence perceived safety during automated driving. Trucks and vehicles with lateral offset to the road centre lead to significantly lower perceived safety. We recommend an adaptive driving trajectory, which modifies trajectory behaviour on different lane widths and adjusts its behaviour on type and position of oncoming vehicles. The results of the study help to design an accepted, preferred and trustfully trajectory behaviour for highly automated vehicles.