Rules Versus Risk: Why Perceptions of Pedestrian Comfort and Safety Differ for Interactions with Self-Driving versus Human-Driven Vehicles

This study aims to inform the development of pedestrian-friendly self-driving vehicle (SDV) policies by investigating how perceptions of pedestrian comfort and safety are affected by SDV technology. We use structural topic modeling to investigate themes in open response survey comments from participants who viewed and rated short video clips of pedestrian interactions with motor vehicles. Although they were all human-driven vehicles (HDVs), participants were told that half of the interactions (randomly for each individual) involved SDVs. This deception-based survey design enabled isolation of the intrinsic effect of automated driving on comfort and safety perceptions across a broad sample of the population. Model results identified latent topics significantly more likely to be discussed for SDV versus HDV interactions, ceteris paribus. There is a greater focus on pedestrian responsibility to be cautious, aware, and predictable in interactions with SDVs than HDVs. Topics more associated with SDVs tend to focus on strict rule compliance (obligation fulfillment), whereas topics more associated with HDVs tend to focus on risk mitigation (with less focus on rules). Recommendations to mitigate potential negative impacts of introducing SDVs on the attractiveness of walking include requirements for conservative SDV operation in city streets, limiting potential interactions that require negotiated priority with SDVs (through physical separation and clear traffic controls), and enhancing external communication from SDVs.