Adaptive cruise control (ACC) vehicles are proving to be the first generation of automated vehicles to enter our roadways in large numbers. Although many theoretical studies find that ACC vehicles have positive impacts in terms of traffic quantities such as throughput and stability, recent studies reveal that commercially-available ACC vehicles may actually be string unstable, which could negatively influence the highway traffic flow. However, it is still unclear what impacts these vehicles will actually have on traffic flow. In this presentation, we address the question of how commercially available ACC vehicles may influence traffic throughput and stability. This question is particularly relevant at highway bottlenecks where, locally, traffic oscillations are triggered by an increase in lane changes during congested periods. With this in mind, the objective of this study is two-fold: (i) investigating the impacts of theoretical ACC vehicles and commercially-available ACC vehicles mixed with human-driven vehicles at different market penetration rates on highway throughput; (ii) exploring the potential relationship between string stability and highway throughput. Specifically, we simulate vehicle dynamics via the intelligent driver model (IDM) with parameter values calibrated to match the performance of a real, commercially-available ACC vehicle and compare the simulation to the behavior of a theoretical AC vehicle that has been shown to improve traffic conditions. Utilizing SUMO, the highway throughput is simulated in scenarios with different ACC vehicle market penetration rates ranging from 0% (baseline) to 100% ACC vehicles.
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