Express What I Think: The Impact of External Human-Machine Interfaces on the Performance of Lane Change Maneuvers

Lane change is a complex behaviour involving subtle interactions among road users. Providing external human-machine interfaces (eHMIs) may improve the safety of lane-changing events. However, previous studies on eHMI mostly focused on the interaction between autonomous vehicles and pedestrians. As a first attempt, we investigated the yielding behaviour of drivers in lane-changing scenarios when different kinds of eHMIs regarding the intentions of the cutting-in vehicles (i.e., command, polite and explanatory) are provided. In a driving simulation experiment with 32 participants, we found that all three eHMIs increased yielding rates and minimum time to collision (minTTC) compared to the baseline condition without eHMI, with the polite eHMI yielding the best results. Regarding subjective evaluation, polite eHMIs were also perceived as having the highest usability. This study underscores the effectiveness of explicitly expressing lane-changing intentions through eHMIs and demonstrates that the eHMI design can influence driver behaviour, usability perception, and traffic safety.