Characterizing Bicyclists Behavior in Overtaking Scenarios Over Different Road Infrastructures

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Virginia Tech


Fatal vehicle-bicycle crashes have increased in the United States while cyclist crashes often go unreported. The underreporting of all cyclist crashes results in the overall pre-crash behavior of the cyclists being unknown. What is known is that the most fatal bicycle crash scenario occurs when a vehicle performs an overtaking maneuver. It is crucial to find effective strategies to mitigate these crashes. Vision Zero aims to eliminate all traffic fatalities and disabling injuries by the year 2050 through the implementation of the safe system approach. One of their approaches is using active safety systems like bicycle detecting automatic emergency braking. The purpose of this study was to characterize bicyclist behavior to enhance the crash avoidance potential of advanced driver assistance systems and improve safety for cyclists. An analysis on fatal crashes involving bicyclists was conducted to determine scenarios for testing bicyclist-vehicle interactions on roadways using virtual reality (VR). VR testing was conducted to capture and analyze bicyclist dynamics. Most fatal bicycle crashes occurred when motorists overtook cyclists, especially when cyclists are travelling in a travel lane in the same direction as traffic. These crashes often happen in densely populated areas with favorable weather conditions. This information was used to construct scenarios representing common fatal bicycle crash scenarios. From the analysis, four scenarios were developed. The first scenario was an overtaking scenario with the cyclist traveling in the same direction as traffic, in a travel lane without a bicycle lane or shoulder. The second, third and fourth scenarios were variations of the first to include a bike lane, shoulder, and both a bike lane and a shoulder to analyze the behavior difference due to the inclusion of each. Participants were immersed in a VR simulator that used the combination of a VR headset and a custom-built stationary bicycle. Eighteen individuals were recruited with an average age of 22.7 years. Participants experienced all four scenarios, and their speed, glance, lane position, and standard deviation of lane position were collected and analyzed. The speed for each road type and overtaking phase did not vary significantly, with an average of 4.9 m/s. In the case where there was neither a bike lane or a shoulder, the cyclists looked towards the vehicle more than the other scenarios. As for the lane position, the scenario where the cyclist had neither a shoulder or a bike lane, led to a closer vehicle-bicycle relative position than the other three scenarios. As for standard deviation of lane position, the road with neither a shoulder or bike lane had the largest interquartile range (IQR) and average and the road with both a shoulder and bike lane had the smallest IQR. This implies a lower predictability of the cyclist's movements when they are riding on a roadway with no support lane. Following the testing, participants rated the perceived realism and interactiveness of the VR world and their comfort in each road design. Most of the participants mentioned that having some allocated space felt more comfortable and lowered their sense of danger. To enhance cyclist safety, adopting Euro NCAP testing for AEB systems in the US is recommended. This form of testing could lead to improvements in AEB systems, reducing crashes with cyclists and injury severity. In terms of road infrastructure improvements increasing the number of bike lanes, adding wider shoulders, or widening lanes could also enhance cyclist safety on roadways.



Overtaking, Virtual Reality, Bicyclist, Behavior, Infrastructure, ADAS, AEB