Gap acceptance study of pedestrians crossing between platooning autonomous vehicles in a virtual environment

• Published in: Transportation research. Part F, Traffic psychology and behaviour Traffic psychology and behaviour, 2019-11, Vol.67, p.1-14
• Main Authors: Woodman, Roger, Lu, Ke, Higgins, Matthew D., Brewerton, Simon, Jennings, Paul A., Birrell, Stewart
• Format: Article
• Language: English
• Subjects: Autonomous vehicles; Electric vehicles; Gap acceptance; Human factors; Pedestrian crossings; Pedestrian gap acceptance; Pedestrians; Platooning; Separation; Strategy; Traffic safety; Traffic speed; Travel; Urban environments; Vehicles; Virtual environments; Virtual reality
• ISSN: 1369-8478; 1873-5517
• DOI: 10.1016/j.trf.2019.09.017

•The paper presents the first study of pedestrian gap acceptance for platoons of low-speed AVs.•A protocol is presented for virtual reality (VR) based gap acceptance testing for AVs.•It was found that ground markings for use as a visual separation between pedestrian and AVs lowers gap acceptance.•People’s perception of safety was less in a shared space compared to the road environment. Autonomous vehicles (AVs) operating in shared urban environments, often referred to as “pods”, will constantly have to interact with pedestrians. As a result, an effective strategy will be required for pods to continue operating, while in close proximity to people. This strategy could be in terms of active negotiation, where a pod identifies a person and gives way; or a more passive strategy, such as requiring pods to travel close together in platoons, in order to reduce the number of individual vehicle encounters. For this latter example, it is critical to understand how the spaces between pods and AVs in general are perceived by pedestrians, and what factors will persuade and dissuade crossing. Therefore, this paper seeks to understand this relationship, and presents results from a pedestrian gap acceptance study for platoons. To ensure the safety of participants, a virtual environment was used instead of real vehicles. The goal of the experiment described in this paper, is to understand the gap acceptance behaviour of participants, when presented with a platoon of pods in different environments. The experiment evaluated four vehicle speeds, from 1 km/h to 16 km/h, four temporal gaps, from 2 s to 5 s, and two environments. These environments were a typical road layout, with footpath and line markings, and a shared space, where all markings and separation between pod and pedestrian were removed. For each scenario, participants were asked if they would cross between the pods and how safe they felt about the situation, recorded as a Likert score. The results suggest that people are more likely to attempt to cross between a platoon of pods when they are travelling closer together in a shared space (no line markings or separation between vehicles and pedestrian), compared to a road environment (separated by raised pavement and road markings). However, it was also found that people’s subjective rating of safeness was higher in the road environment, when presented with a platoon of pods, compared to the shared space.