Empirical Analysis of a Freeway Bundled Connected-and-Automated Vehicle Application Using Experimental Data

Connected-and-automated vehicles (CAV) hold the potential for substantial improvements to traffic safety, travel time reliability, driver comfort, roadway capacity, environmental impacts, and users’ overall travel experience. Numerous modeling and simulation studies have been conducted to evaluate these impacts. However, model accuracy and simulation assumptions limit the validity of evaluation results. These factors have resulted in the wide range of differences in effectiveness among studies examining the same CAV applications available in the literature. In this study, we propose a bundled CAV application that involves platoons of equipped vehicles governed by an integrated set of cooperative adaptive cruise control (CACC), cooperative merge, and speed harmonization applications. We implemented the bundled application in a fleet of five vehicles at the Saxton Transportation Operations Lab of the Federal Highway Administration. Experiments were conducted to collect and compare data on CAV and human-driven behavior. Based on the real experimental data, our results show that the performance of the CAV operations, including platooning and cooperative merging under varying Infrastructure-to-vehicle speed commands, demonstrate string stability. The results also present key behavioral parameters of the vehicles and strings. This will eventually help the research community, particularly the modelers, to come up with models with realistic performance to further understand the CAV impacts on traffic. The results can also serve as references for transportation agencies to make informed decisions on infrastructure and traffic management decisions.