Fuel-Efficient Heavy-Duty Vehicle Platoon Formation

Sammanfattning: There is a need for intelligent freight transport solutions as the demand for road freight transport is continuously increasing while carbon footprint needs to be significantly reduced. Heavy-duty vehicle (HDV) platooning is one potential solution to partially mitigate the environmental impacts as well as to reduce fuel consumption, improve traffic safety, and increase traffic throughput on congested highways. However, as each goods transport has different origin, destination, and time restriction, it is not evident how the HDVs, carrying the goods, can fully utilize the platooning benefits during individual transport missions. Thus, there is a need to systematically coordinate scattered vehicles on the road to form platoons in order to maximize the benefits of platooning.  This thesis addresses the problem of merging scattered HDVs to form platoons in traffic. The first contribution of the thesis is the investigation of how and when a pair of HDVs should form platoons given their positions, speeds, and destinations. We formulate the problem as an optimization problem and we derive a break-even ratio that describes how far a vehicle should check for possible vehicles to platoon with. The second contribution is to consider traffic during the merging maneuver when forming a platoon. Traffic may disturb and delay when the two HDVs will form a platoon and such delay leads to less fuel saved than initially planned. Based on shockwave and moving bottleneck theories, we derive a merge distance predictor that calculates where the HDVs will merge depending on the traffic condition. We first validate this in a microscopic traffic simulation tool. Then, we also conduct an experimental study during one month on a public highway between Stockholm and Södertälje to evaluate the merging maneuver with different traffic densities. Lastly, we use vehicle probe data obtained from a fleet management system to investigate the potential fuel savings from coordination in a larger road network. The number of vehicles platooning can be increased significantly through coordination compared to today.  The main result of this thesis indicates that merging HDVs to form platoons leads to great fuel savings and that there are significant potentials to do so in reality. Traffic needs to be considered in order to guarantee that the HDVs save fuel and deliver the goods in time. Furthermore, the earlier the transport assignment is planned ahead of time, the more opportunities there are to collaborate with other fleet owners to reduce the fuel consumption.