Driver Trust in Automated Driving Systems: The Case of Overtaking and Passing

It is important to learn about the factors that affect a driver's willingness to rely on an automated driving system in order to maintain appropriate trust in the system. The purpose of this study was to investigate the relationships between the system behavior and a driver's trust by considering overtaking a scooter and passing a bicycle automatically. Using a driving simulator, we first investigated the peak driving speed, the peak lateral distance between the object and the test vehicle, and the first steering input timing of human drivers while overtaking or passing. Next, the obtained data were applied to the parameters to design an automated driving system. Finally, we investigated the effects of differences in system behavior on drivers' trust by varying the system parameters. The results demonstrated that drivers' trust varied according to these three parameters. Moreover, the analysis indicated that an automated driving system should maintain longer peak lateral distances and engage in steering manoeuvres earlier than human drivers would in order to maintain a subjectively appropriate lateral distance and steering manoeuvre start time, respectively. Furthermore, the peak driving speeds for overtaking or passing should be kept almost equal to the manual speeds of human drivers to maintain subjectively appropriate driving speeds.