Perceived Time To Collision as Public Space Users' Discomfort Metric

TL;DR

This paper proposes perceived Time To Collision (TTC) as a new metric to quantify discomfort among public space users, validated through experiments with e-scooters and pedestrians, and applicable to advanced driver assistance systems.

Contribution

Introduces perceived TTC as a novel, quantifiable discomfort metric for shared public spaces, validated through controlled experiments and applicable to vehicle assistance systems.

Findings

Strong correlation between perceived TTC and reported discomfort

TTC only requires relative velocity and position data

Potential for TTC to be used in advanced driver assistance systems

Abstract

Micro-mobility transport vehicles such as e-scooters are joining current sidewalk users and affect the safety and comfort of pedestrians as primary sidewalk users. The lack of agreed-upon metrics to quantify people's discomfort hinders shared public space safety research. We introduce perceived Time To Collision (TTC) as a potential metric of user discomfort performing controlled experiments using an e-scooter and a pedestrian moving in a hallway. The results strongly correlate the participant's reported discomfort and the perceived TTC. Therefore, TTC is a potential metric for public space users' discomfort. Since the metric only uses relative velocity and position information, it is a viable candidate for neighboring people's discomfort estimation in advanced driver assistance systems for e-scooters and PMVs. Our ongoing research extends the results to mobile robots.