Unsafe and inefficient communication between automated buses and road users on public roads in Japan

For an appropriate communication design between an automated vehicle and road users, we need to understand unsafe and inefficient communications in public road environments. This study investigated unsafe and inefficient communications between automated buses and road users and analyzed the underlying factors. We collected video data from a camera attached to a bus for 233 days in a field operation test (FOT) at seven locations in Japan and observed 22,199 communications between the automated bus and road users. Consequently, we observed several types of unsafe and inefficient communications. We found that specific automated bus characteristics, such as absence of driver's action, unfamiliar appearance, and fixed trajectory, caused these unsafe and inefficient communications in crossing and overtaking scenarios. Our study indicates the necessity of some improvements for implicit/explicit cues from an automated bus, along with the education of residents and visitors.