Influence of Surrounding Traffic and System Behaviors on Driver-Initiated Automation Disengagements in Urban Overtaking Scenarios

ObjectiveThis study investigates the factors influencing drivers' decisions to intervene in conditional driving automation (SAE Level 3) without system alerts or failures.BackgroundIn complex traffic environments, mismatches between drivers' perception of traffic situations and the response of automation can lead to driver-initiated disengagements, even when the system can safely manage events. While such interventions may be safety conservative, they can also disrupt system operations, compromise safety, and reduce user trust.MethodA driving simulation with 23 participants was conducted in which a conditionally automated vehicle encountered a stopped vehicle blocking its lane, with oncoming traffic present in the adjacent lane. The system was programmed to safely overtake using the opposing lane considering the distance to the oncoming traffic. Participants could either remain in automated mode or override the system.ResultsDrivers intervened in more than 20% of events, most often by pressing the brake pedal while approaching the stopped vehicle when the gap to the oncoming traffic was perceived as insufficient. In challenging overtaking gaps, discrepancies between the behavior of a leading human-driven vehicle and the system further increased intervention likelihood, with some drivers misunderstanding the system's ability to detect oncoming vehicles. Although drivers who intervened completed overtaking faster than the system, their maneuvers were marked by abrupt steering and acceleration, raising concerns about encroaching into opposing traffic.ConclusionEnhancing system feedback and better aligning automation behavior with driver expectations may reduce unnecessary disengagements.ApplicationThe findings provide guidance for designing more intuitive automated driving systems that enhance user trust and safety.