What externally presented information do VRUs require when interacting with fully Automated Road Transport Systems in shared space?

Abstract

As the desire for deploying automated ("driverless") vehicles increases, there is a need to understand how they might communicate with other road users in a mixed traffic, urban, setting. In the absence of an active and responsible human controller in the driving seat, who might currently communicate with other road users in uncertain/conflicting situations, in the future, understanding a driverless car's behaviour and intentions will need to be relayed via easily comprehensible, intuitive and universally intelligible means, perhaps presented externally via new vehicle interfaces. This paper reports on the results of a questionnaire-based study, delivered to 664 participants, recruited during live demonstrations of an Automated Road Transport Systems (ARTS; SAE Level 4), in three European cities. The questionnaire sought the views of pedestrians and cyclists, focussing on whether respondents felt safe interacting with ARTS in shared space, and also what externally presented travel behaviour information from the ARTS was important to them. Results showed that most pedestrians felt safer when the ARTS were travelling in designated lanes, rather than in shared space, and the majority believed they had priority over the ARTS, in the absence of such infrastructure. Regardless of lane demarcations, all respondents highlighted the importance of receiving some communication information about the behaviour of the ARTS, with acknowledgement of their detection by the vehicle being the most important message. There were no clear patterns across the respondents, regarding preference of modality for these external messages, with cultural and infrastructural differences thought to govern responses. Generally, however, conventional signals (lights and beeps) were preferred to text-based messages and spoken words. The results suggest that until these driverless vehicles are able to provide universally comprehensible externally presented information or messages during interaction with other road users, they are likely to contribute to confusing and conflicting interactions between these actors, especially in a shared space setting, which may, therefore, reduce efficient traffic flow.

Pedestrian Trust in Automated Vehicles: Role of Traffic Signal and AV Driving Behavior

“…This is often done to communicate the drivers' intent when negotiating the right-of-way with pedestrians (Sucha et al, 2017). In the absence of a human driver, it is not surprising that pedestrians have expressed concerns over not knowing or understanding the AV's intention (Merat et al, 2018;Reig et al, 2018). A clear understanding of the AV's intention is thus expected to foster trust in the AV and ultimately AV acceptance (Saleh et al, 2017;Liu et al, 2018).…”

Prioritizing Safety or Traffic Flow? Qualitative Study on Highly Automated Vehicles’ Potential to Prevent Pedestrian Crashes with Two Different Ambitions

“…Lundgren et al [12] argued that eye-contact should be replaced in one way or another to ensure safe interaction with HAVs. Especially in shared space areas, conflicting interactions between HAVs and pedestrians are likely without understandable communication [2].…”

“…Although these hypothetical procedures could ensure pedestrian safety, some other negative effects could be realized involving, for example, flow of traffic, travel times, and risk of rear-end crashes, when there are also conventional, driver-managed vehicles in traffic. It seems clear that a strategy or regulation should be implemented for the encounters in traffic between HAVs and other road users [2].…”

“…The conversation about the safety benefits of HAVs has mostly focused on the elimination of driver errors, which may be the key factor to consider in collisions between motor vehicles. However, in the encounters between HAVs and other road users (e.g., pedestrians and cyclists), interaction between vehicle automation and humans is an important factor from the perspective of safety [2]. The elimination of driver error is also an important factor for improved safety in these encounters, but changes in interaction and behavior cause potentially new safety problems [3].…”

Pedestrian Decision-Making Responses to External Human-Machine Interface Designs for Autonomous Vehicles

“…The IEEE community has demonstrated growing interest in the interaction between autonomous vehicles and vulnerable road users (VRUs) such as pedestrians and cyclists [1], usually focusing on the technology to detect pedestrians and their intention to cross [2]. Research has attempted to understand how vehicles should communicate their manoeuvring intention(s) to pedestrians and cyclists via external humanmachine interaction (HMI) [3]. These interactions are particularly problematic when VRUs have to share the same environments with autonomous vehicles, for example, in semipedestrianised areas.…”