Optimizing lane configurations for efficient platoon control during lane closures

In the era of Connected and Autonomous Vehicles (CAVs), optimizing transportation infrastructure is crucial to unlock the full potential of Connected and Autonomous Technology (CAT), particularly in the context of advanced operations like platooning. While numerous studies have highlighted the operational advantages of platooning, it is not without its challenges, including potential inconveniences to other road users during lane changes, and these issues become more pronounced when vehicles encounter lane merges due to closures, raising concerns about traffic safety. In response to these challenges, this study focused on infrastructure modifications, with a specific focus on low-automation CAVs. The study employed microsimulation software developed by PTV VISSIM to model a variety of scenarios on a freeway segment, considering six distinct lane configuration scenarios, varying Market Penetration Rates (MPRs), and factors such as platoon allowance/restriction within a one-mile buffer upstream of lane closures, as well as open or closed lane conditions (dedicated lanes). Operational performance results were obtained from VISSIM output files, while traffic safety was assessed using Surrogate Safety Assessment Tool (SSAM) developed by Federal Highway Administration (FHWA). The findings revealed that, for a two-lane segment, restricting platoons to open lanes and allowing them on upstream one-mile resulted in a 28% reduction in the total number of conflicts, with Time-To-Collision (TTC) serving as the conflict indicator. Additionally, speeds and delays improved when compared to the base condition without platoons. However, in closed lane conditions, allowing platoons upstream led to more conflicts compared to the alternative case. The worst-case scenario involves allowing platoons without any lane restrictions, leading to a substantial increase in conflicts at higher MPRs. The insights gained from this study can be instrumental for Traffic agencies in formulating effective strategies during the initial stages of platoon deployment on freeways, with the aim of enhancing both safety and operational efficiency.