The aim of this research is to objectively and subjectively validate the virtual reality Bicycle Simulator (BS) developed using off-the-shelf components at the University of Győr, Hungary. To this end, this research compares the performance of 32 participants in two real-world environments (Site 1: separated bicycle-pedestrian path and Site 2: advisory bicycle lane) and in their replication in virtual reality (VR). The objective measures collected for the comparison include speed and Cumulative Lateral Position (CLP), whereas subjective measures include the Perceived Level of Realism (PLR) based on participants’ self-reported perceptions in a post-experiment questionnaire. PLR is a new indicator that we propose using subjects' perceptions of speed, BS control, and VR representation. The combination of these subjective and objective measures is proposed as the Degree of Realism (DR) to standardise the classification of the realism level of a bicycle simulator. Subjectively, the results indicate that the BS provides a high level of safety and comfort for conducting such research. Subject characteristics have no significant influence on VR sickness scores or Perceived Level of Realism. Objectively, for both speed and CLP, we found no significant difference between on-site and the simulation measurements in the case of Site 1, but otherwise for Site 2. However, subjects were not able to accurately perceive either the actual or the relative differences. In conclusion, our bicycle simulator is a safe and comfortable traffic safety research tool that needs further improvement. The proposed preliminary concept of the degree of realism requires further investigation.

The aim of this paper is to investigate the safety of cyclists while interacting with autonomous vehicles (AVs) in an uncontrolled T-intersection using PTV Vissim microsimulation combined with the Surrogate Safety Assessment Model (SSAM). For the microsimulation, three cycling behaviours were constructed (cautious, normal, and aggressive), and two AV behaviours (cautious and normal) were adopted. 87 h of microsimulation resulted in 230 conflicts. The type and nature of these conflicts, as well as two temporal indicators and four speed-related indicators were analysed. Nearly 96% of the conflicts were rear-end collisions, and almost 70% were conflicts where the cyclist was the first to arrive at the conflict point. Interestingly, the least involved cycling behaviour in conflicts was aggressive and the most involved was cautious. A significant relationship was found between severity clusters of temporal indicators and cycling behaviour. It is also concluded that an important future research direction would be the construction of a two-dimensional conflict diagram with severity thresholds specifically for bicycle-vehicle interactions.

The introduction of autonomous vehicles (AVs) in urban environments where cycling activity is present has raised the need to investigate potential modifications to urban roads, not only from the perspective of AVs but also from the perspective of cyclists. This study aims to investigate the effect of different road design characteristics and varying traffic penetration rates of AVs, using a bicycle simulator study. 50 participants assessed their perceived level of safety, comfort and stress in 11 randomized scenarios. The scenarios involve a design with sharrows and four designs with separated cycling lanes (with two different cycling lane width and two pavement painting options), with 3 AV traffic penetration rates (TPR): 0 %, 50 %, and 100 %. A series of cumulative link mixed models (CLMM) was estimated to analyze the impact of design characteristics and TPRs on cyclist perceptions. The results revealed that the implementation of AVs in shared road scenarios did not improve cyclist safety. On the contrary, it has significantly reduced the perceived level of comfort and has significantly increased the perceived level of stress. However, in separated cycling lane designs, the presence of AVs was found to positively affect cyclist perceptions, although this impact was not significant. Furthermore, the study revealed that the most important factor that affects perceptions of safety, comfort, and stress is the separation between traffic and cycling lanes.