Impact of eHMI on Pedestrians' Interactions with Level-5 Automated Driving Systems

TL;DR

This study shows that external human-machine interfaces (eHMIs) on Level-5 automated vehicles improve pedestrian understanding, safety perceptions, and trust, leading to more confident and earlier crossing decisions in simulated scenarios.

Contribution

It provides empirical evidence that eHMIs enhance pedestrian-ADS communication, with visual cues being more necessary, thereby advancing design guidelines for safer autonomous vehicle interactions.

Findings

Pedestrians crossed earlier with eHMIs

Perceived safety and trust increased significantly

Visual eHMI features preferred over auditory cues

Abstract

Each year, over half of global traffic fatalities involve vulnerable road users (e.g. pedestrians), often due to human error. Level-5 automated driving systems (ADSs) could reduce driver errors contributing to pedestrian accidents, though effectiveness depends on clarity and understandability for other road users. External human-machine interfaces (eHMIs) have been proposed to facilitate pedestrian-ADS communication, though consensus on optimal eHMI features remains unclear. In an online survey, 153 participants responded to road-crossing scenarios involving level-5 ADSs, with and without eHMIs. With eHMIs, pedestrians crossed earlier and more confidently, and reported significantly increased perceptions of safety, trust, and understanding when interacting with level-5 ADSs. Visual eHMI features (including a text display and external speedometer) were ranked more necessary than auditory ones, though auditory cues received positive feedback. This study demonstrates that eHMIs can significantly improve pedestrians' understanding of level-5 ADS intent and enhance perceived safety and trust, facilitating more intuitive pedestrian-ADS interactions.