In Search of Severity Dimensions of Traffic Conflicts for Different Simulated Mixed Fleets Involving Connected and Autonomous Vehicles

Abstract

-is study aims to estimate the severity of con3icts that may arise from the introduction of connected and automated vehicles (CAVs) by examining the vehicle paths generated by microsimulations of mixed 3eets of human-driven vehicles and CAVs with di9erent levels of automation (L1-L4 vehicles). -e study assesses the severity of con3icts using a holistic approach that considers three dimensions: (1) proximity to collision, via the time-to-collision (TTC) indicator; (2) potential consequences of a con3ict, via single surrogate safety measures such as maximum speed (MaxS) and vehicle speed di9erence (DeltaS); and (3) a combination of both dimensions to assign severity scores, via TTC and velocity vectors. -e study’s >ndings suggest that moderate penetration rates of L3 and L4 vehicles (35–55%) show signi>cant di9erences in the number of traAc con3icts with varying TTC values. Additionally, high penetration rates of L3 and L4 vehicles (above 55%) result in lower values of con3ict consequences measures such as MaxS and DeltaS. Furthermore, the study shows that con3ict consequences decrease if the follower is a L3 or L4 vehicle. -e study’s >ndings also reveal that there is a considerable reduction in high severity con3icts when the penetration rate of CAV levels reaches 50%, and the full operation of L4 vehicles results in a 75.5% reduction in high severity con3icts. -erefore, this study provides valuable insight into the potential severe con3icts during the transition period from manual vehicle operation to full CAV operation. Overall, the study’s >ndings highlight the importance of assessing the severity of potential con3icts arising from the introduction of CAVs. By considering the proximity to collision and the potential consequences of con3icts, the study provides a comprehensive assessment of the severity of con3icts. -is information can inform the development of policies and strategies to ensure the safe and responsible introduction of CAVs into our transportation systems.