Pedestrian decision-making responses to external human-machine interface designs for autonomous vehicles

As part of a large UK-funded autonomous vehicle project (UK Autodrive), we examined pedestrian attitudes and road-crossing intentions using a real autonomous vehicle (AV) in an indoor arena. Two conceptual external human-machine interfaces (HMIs) were presented to display the vehicle's manoeuvring intentions. Participants experienced a simulated road-crossing task to assess their interactions with the AV. Although neither HMI concept was entirely free of criticism, there were objective performance differences for a projection-based HMI concept, as well as critical subjective opinions in pedestrian responses to specific manoeuvring contexts. These provided insight into pedestrians' safety concerns towards a vehicle where bi-directional communication with a driver is no longer possible, with suggestions for future vehicle HMI concepts