Different Types, Different Speeds – The Effect of Interaction Partners and Encountering Speeds at Intersections on Drivers’ Gap Acceptance as an Implicit Communication Signal in Automated Driving

Abstract

AbstractTo exploit the benefits of automated vehicles (AVs), the systems’ functions need to be accepted by the driver and other traffic participants. Thus, the human-machine interaction should be considered as a key issue. Manual driving is often coordinated by implicit communication cues. Therefore, specific parameters such as drivers’ gap acceptance (GA) should be investigated to be prospectively implemented in AVs. The current study aimed at identifying the effects of different interaction partners, encountering speeds and participants’ age and gender on GA. The video material displayed a left-turn scenario from the drivers’ perspective including encountering interaction partners from the left. The study investigated four different interaction partners (passenger car, motorcycle, e-scooter, bicycle), all approaching at four different speeds (10/15/20/25 km/h). In sum, 121 participants contributed to the online study. The results revealed main effects for interaction partner, encountering speeds and participants’ age on GA. Participants selected the smallest comfortable time gaps for the bicycle and the largest gaps for the passenger car, indicating that participants anticipated the potential threat of the interaction partner when selecting comfortable gaps. In accordance with previous studies, smaller gaps were accepted at higher speeds resulting in riskier decisions. Younger participants accepted smaller gaps than older participants did. Hence, AVs should consider the types and the speeds of the encountering interaction partners when selecting a comfortable gap as a form of implicit communication. Moreover, drivers’ characteristics should also be considered when implemented driving styles in AVs, e.g., by selectable driving style profiles.KeywordsImplicit communicationGap acceptanceAutomated driving