To Cross or Not to Cross: Urgency-Based External Warning Displays on Autonomous Vehicles to Improve Pedestrian Crossing Safety

Autonomous vehicles (AV) may be able to show visual displays on their external surface to support pedestrian communication with the AV. Pedestrian crossing at uncontrolled locations is safety-critical and clear communication between the pedestrian and the AV is important in this situation. However, research to date has not been clear on how the AV should communicate with pedestrians. We designed two sets of warnings on AVs based on the perception of warning urgency. Each set consisted of three warnings that differed in color and flashing pattern and indicated distinct safety-related information. A survey was conducted to investigate how people make decisions, warnings within and outside of the driving context, and perceived warning compliance. Results showed that people were risk averse in crossing and cars with warning displays were perceived as more urgent. This paper contributes uniquely in exploring research-based approaches on designing warnings to improve pedestrian crossing safety.