Selection method of formation strategies for trucks catching and waiting on freeway

Truck platoons with connected and autonomous driving systems reduce fuel consumption and optimize road space, saving energy and enhancing transportation efficiency. In long-haul freight transport on freeway, Trucks can adopt two strategies: catching up with front platoons or waiting for platoons behind. The choice of both methods also involves balancing fuel consumption and time cost. This study focuses on freeway freight trucks. Firstly, the platooning space domain models of formation strategies for catching and waiting were established based on vehicle dynamics theory and transportation economics, and the calculation method for critical distance between vehicles and platoons was established by using the space domain models. Secondly, based on the generalized cost theory, the platoon benefit calculation methods for two formation strategies were established, which was used to provide decision-making basis for vehicles to choose between the two formation strategies. Finally, the transportation from Changchun to Shenyang in China was used as the case study, and the impact of vehicle speed and the speed of platoons on the benefits of two formation strategies decision-making methods was analyzed. The results indicate that it is suitable to adopt a catching formation strategy under a higher vehicle speed (100 km/h), and waiting formation strategy more suitable for low-speed scenarios (60 km/h). In addition, after increasing the platoon speed within the range of 80–100 km/h, the platoon benefits of catch-up and waiting formation strategies increased by an average of 346.12 RMB and 440.15 RMB, respectively. It indicates that the platoon benefits under two formation strategies are positively correlated with the platoon speed. Therefore, when vehicles can adopt both catching and waiting formation strategies simultaneously, it’s suitable to adopt the catch-up formation strategy if the speed of platoon ahead is greater than that of platoon behind, otherwise, it’s suitable to adopt a waiting formation strategy.