Overcoming critical interface design challenges for Automated Vehicle-cyclist interaction

Abstract

Cyclists are vulnerable road users who must share the road with motorised vehicles [66]. They rely on social interactions with drivers to resolve space-sharing conflicts safely and without ambiguity [82]. The advent of automated vehicles (AVs) will remove these social interactions, compromising the safety of cyclists [97]. AV-cyclist interfaces are promising solutions; these devices facilitate clear communication by allowing AVs to communicate explicit signals [37]. For example, displaying the AV’s intentions via LED lights on the AV or augmented reality glasses worn by cyclists [67]. However, AV-cyclist interfaces must overcome four key design challenges to be usable on real roads: acceptability to match the needs and requirements of cyclists [41, 49]; versatility to operate across various traffic scenarios, such as intersections or roundabouts [12]; cultural inclusivity between countries with different cultural norms and traffic infrastructure [108], and scalablity for many-to-many AV-cyclist interaction [123]. This thesis describes 10 studies conducted to overcome these challenges. These established requirements for AV-cyclist interfaces through observations and eye-tracking studies conducted in real traffic. The requirements were used to design interfaces through participatory design and test them in outdoor and simulator-based user studies. Findings for acceptability showed that interfaces should be placed on the surrounding environment or the AV itself to avoid compelling cyclists to carry devices on every trip. However, optional wearable devices can be used for added support. Results for versatility showed that AV-cyclist interfaces must be viewable from anywhere around the vehicle, and the AV’s intentions should be communicated in a simple, binary manner (i.e., AV-yielding or not yielding) to work consistently between traffic scenarios. Investigating cultural inclusivity showed that interfaces were needed to facilitate interaction regardless of the cultural setting. Cyclists accustomed to riding in mixed traffic found interface messages on AV intentions sufficient. However, those accustomed to greater segregation from vehicles needed to verify these messages with AV driving behaviours. For scalability, results showed that incorporating additional wearable devices was useful to avoid ambiguity in multi-cyclist situations and centralise information from multiple AVs. Multi-AV information should be communicated using visual and auditory signals without diverting cyclist attention from the road ahead, e.g. by integrating visual displays into the environment. The thesis contributes novel design guidelines for each design challenge. This is critical for supporting the large scale, global deployment of AVs and ensuring safe cycling experiences