Developing vehicle platoons and predicting their impacts

Future Intelligent Transportation System strategies that use cooperative automation have the potential to greatly improve transportation network performance and infrastructure efficiency. One of these strategies, vehicle platooning, uses wireless communication to allow a group of vehicles to move as a single unit with small, constant, time headways. This raises the capacity of a highway and increases the stability of traffic flow. This dissertation first addresses the controller design for platooning, which is the algorithm used by platooning vehicles to control their speed trajectory. Second, it considers the capacity impact of platooning on highway basic segments by developing an analytical model geared towards equipping planners and engineers to plan for the future. For the controller design, a multi-vehicle look ahead feedforward-feedback control structure is proposed. This approach allows vehicles to be proactive about responding to downstream traffic. However, depending on the controller design, in certain situations, a multi-vehicle look ahead approach may not give enough attention to the immediately preceding vehicle which may be a safety concern. Thus, to increase safety, the proposed controller varies the attention given to downstream vehicles based upon the relative location of all downstream vehicles in the platoon. The controller is further updated to allow vehicles to focus on the first vehicle in the platoon, whenever safe, which is proven to maximize platoon stability. Through simulations and live experiments, the final controller design displays stable performance which is important to positively impact upstream traffic. For the impact of platooning on capacity of highway basic segments, an analytical model is proposed, which accounts for variables such as market penetration rate, to determine the average time headway which is directly related to capacity at saturation conditions. The model works by estimating the probability that a randomly chosen vehicle will be in a number of different following modes under which it will maintain a different time headway. Determining when to open dedicated lanes for platooning purposes is also part of the model. In addition, to allow for analysis in conjunction with the Highway Capacity Manual, methods that determine the passenger car equivalent of platooning enabled passenger cars are presented.