Blinded windows and empty driver seats: The effects of automated vehicle characteristics on cyclists’ decision‐making

Abstract

Automated vehicles (AVs) may feature blinded (i.e. blacked-out) windows and external human-machine interfaces (eHMIs), and the driver may be inattentive or absent, but how these features affect cyclists is unknown. In a crowdsourcing study, participants viewed images of approaching vehicles from a cyclist's perspective and decided whether to brake. The images depicted different combinations of traditional vehicles versus AVs, eHMI presence, vehicle approach direction, driver visibility/window-blinding, visual complexity of the surroundings, and distance to the cyclist (urgency). The results showed that the eHMI and urgency level had a strong impact on crossing decisions, whereas visual complexity had no significant influence. Blinded windows caused participants to brake for the traditional vehicle. A second crowdsourcing experiment aimed to clarify the findings of Experiment 1 by also requiring participants to detect the vehicle features. It was found that the eHMI 'GO' and blinded windows yielded high detection rates and that driver eye contact caused participants to continue pedalling. To conclude, blinded windows increase the probability that cyclists brake, and driver eye contact stimulates cyclists to continue cycling. Our findings, which were obtained with large international samples, may help elucidate how AVs (in which the driver may not be visible) affect cyclists' behaviour.

Crossing the street in front of an autonomous vehicle: An investigation of eye contact between drivengers and vulnerable road users

“…Thus, it has been argued that such a kind of eHMI could help pedestrian participants to ignore the state of the driver if they realized they were facing an AV ( Faas et al, 2021 ). Consistently, in their scenario-based immersion experiment, Bazilinskyy et al (2022) showed that when cyclists were about to cross in front of an AV with a inattentive driver who was texting inside, they were likely to want to keep pedaling if the AV was exhibiting a “GO” message on a screen eHMI in contrast to no eHMI device. A similar pattern of results was observed in the authors’ study ( Bazilinskyy et al, 2022 ) when the AV had tinted windows, i.e., when the drivenger was no longer visible.…”

“…Consistently, in their scenario-based immersion experiment, Bazilinskyy et al (2022) showed that when cyclists were about to cross in front of an AV with a inattentive driver who was texting inside, they were likely to want to keep pedaling if the AV was exhibiting a “GO” message on a screen eHMI in contrast to no eHMI device. A similar pattern of results was observed in the authors’ study ( Bazilinskyy et al, 2022 ) when the AV had tinted windows, i.e., when the drivenger was no longer visible. Hence, these results suggested removal of uncertainty among cyclists, driven by the text message crossing advice exhibited by the AV.…”

“…Moreover, one could surmise that the effect of the state of the human driver on eye contact communication would be modulated by the presence of the eHMI (H3), as suggested by previous work ( Faas et al, 2021 ; Bazilinskyy et al, 2022 ). Hence, we predicted an interaction effect between these two variables with eye communication being lessened in the presence of an attentive drivenger when the approaching car exhibited an eHMI signal (Experiments A–C).…”

“…Indeed, it has been highlighted that road users are likely to use informal non-verbal communication cues in order to express and attribute intentions, in particular during complex and confusing situations ( Rasouli et al, 2017 ; Sucha et al, 2017 ; Liu Y. et al, 2020 ; Bazilinskyy et al, 2022 ). For example, by analyzing 650 video clips of real traffic scenes in different countries, Rasouli et al (2017) found that gaze was the most prominent form of non-verbal communication cue used by pedestrians in order to transmit a crossing intention to an upcoming car driver.…”

“…Consistently, based on focus group interviews, Liu Y. et al (2020) reported that pedestrians sought communication with vehicle drivers, especially on unsignalized roads, or when vehicles are on standby, turning or reversing, or when priority rules are not clear. With regard to cyclists, Bazilinskyy et al (2022) revealed through a scenario-based immersion experiment that blinded windows of an approaching car at an intersection increased the cyclists’ willingness to brake when crossing, while detectable driver eye contact caused them to want to continue pedaling. There is therefore a body of evidence suggesting that road users feel the need to make eye contact with drivers before making their crossing decisions, most likely to remove the ambiguity about who has the right of way and make safer crossing decisions.…”