Safety Implications of Automated Vehicle Providing External Communication to Pedestrians

Research Team: Ching-Yao Chan (lead), Peggy Wang, Sanaz Motamedi, Teresa Canas Bajo, Xiao Zhou, Shouming Qi, Tingting Zhang, and David Whitney

UC Campus(es): UC Berkeley

Problem Statement: The interaction between automated vehicles (AVs) and vulnerable road users such as pedestrians and cyclists has been recognized as an area of importance. As of May 2018, the California Department of Motor Vehicles (DMV) has issued Autonomous Vehicle Testing Permits to 53 entities, with safety drivers inside of the vehicle. In April 2018, the revised regulations governing the safe deployment of autonomous vehicles took effect, and this opens the door to entities who want to test vehicles without safety drivers on California’s public roads. A relatively less explored area is vehicle-pedestrian interaction from the human-factors perceptive.

Project Description: This project conducted experimental tests comparing different types of external communication interfaces for autonomous vehicles (AVs) in order to investigate pedestrians’ behavior while interacting with AVs. Participants simulated crossing an un-signaled street intersection with an oncoming vehicle. Three types of external communication interfaces were tested: text displaying status of vehicle (vehicle “moving,” “stopping,” “starting”); cross / don’t cross symbols (open hand, man walking) advising pedestrians on what action to take; animated eye (closed eyes, open eyes) letting pedestrians know if the vehicle was aware of the pedestrian or not. For comparison, tests were also run with AVs without an external interface and with human driven vehicles. Test subjects’ eye movements were monitored to see what visual cues they used to judge whether it was safe to cross. The project found little change to a pedestrians’ behavior when interacting with automated vehicles relative to conventional vehicles. Pedestrians mostly rely on vehicle movement pattern (e.g., slowing down) when deciding to cross a street. However, pedestrians also pay attention to an AV’s external communication interface when deciding when it is safe to cross. External interfaces have a positive effect on pedestrians’ trust and perceived safety of AVs and will be valuable in encouraging public acceptance of AVs.

Status: Completed

Budget: $80,000

Project Partner(s): Caltrans

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