Coordination and Routing for Fuel-Efficient Heavy-Duty Vehicle Platoon Formation

Sammanfattning: Heavy-duty vehicle (HDV) manufacturers and fleet owners are facing great challenges for a maintained sustainable transport system as the demand for road freight transport is continuously increasing. HDV platooning is one potential solution topartially mitigate the environmental impacts as well as to reduce the fuel consumption, improve safety, and increase the throughput on congested highways. Although the concept of vehicle platooning has existed for decades, it has only been recently possible to implement in practice. Advancement in information and communications technology as well as in on-board technology allow the vehicles to connect with each other and the infrastructure. As goods have different origins, destinations, and time restrictions, it is not evident how the HDVs can fully utilize the platooning benefits during transport missions. There is a need to systematically coordinate scattered vehicles on the road network to form platoons in order to maximize the benefits of platooning. This thesis presents a framework for the coordination of HDV platoon formations. The focus lies on analyzing and validating the possibility to form platoons through fuel-efficient coordination decisions. A functional architecture for goods transport is presented, which divides the overall complex transport system into manageable layers. A vehicle model is developed to compute the impact a coordination decision has on the fuel cost. Platoon coordination consists of rerouting vehicles, adjusting departure times, and adjusting speed profiles. The focus in this thesis is on adjusting vehicles’ speeds through catch-up coordination. The first main contribution of the thesis is the investigation of how and when a pair of vehicles should form platoons given their position, speed, and destination. We derive a break-even ratio where the fuel cost of catching up and platooning is equal to the fuel cost of maintaining the original profile. By comparing the distance to destination and the distance to the candidate vehicle ahead with the break-even ratio, we can conclude whether a catch-up coordination would be beneficial or not. We also show that the road topography has little or no impact on the fuel savings of catch-up coordination. The second contribution is the study of extending the catch-up coordination into a road network with scattered vehicles with the possibility to form platoons and plan routes on junctions. Incoming vehicles on a road junction are aware of other incoming vehicles and of their position, speed, and destination. The vehicles can decide if a platoon should be formed and which path to take. Simulations on the German road network show fuel savings exceeding 5% with a few thousand vehicles. For our third contribution, we use real vehicle probe data obtained from a fleet management system to investigate how catch-up coordination and departure time adjustments can increase the fuel savings from today’s spontaneous platooning. The results show that coordination can increase the fuel savings and the platooning rate significantly. We managed to increase it with a factor of nine despite having only 200–350 active HDVs on the network. The main results of the thesis indicate that it is possible to increase fuel savings noticeably with simple regional coordination schemes for vehicle platoons.