Platooning Strategy for Trucks on Freeways Based on a Generalized Cost Function

When forming a platoon, trucks equipped with connectivity and autonomous driving capabilities can reduce the fuel consumption of the following trucks while minimizing road space usage. This improves transportation efficiency, conserves energy, and lowers the risk of traffic accidents. Beyond fuel consumption, time cost is a crucial factor in freight transportation and significantly influences platooning strategies. This paper focuses on trucks operating on freeways and develops separate models for fuel consumption and time costs based on truck dynamics and transport economics. A comprehensive cost function integrates these models to construct a truck platooning spatial domain model. To solve this model, we introduce a platooning spatial domain model using the platooning discriminant coefficient, enabling the calculation of the critical distance threshold between trucks and suitable platoons. Additionally, we propose the concept of platooning incentive factors to quantify the benefits of platooning driving compared with individual driving. Furthermore, we provide a decision-making basis when multiple platoons are available. A case study on the route from Changchun to Shenyang in China investigates the effects of four key parameters on the critical platooning threshold and its benefits: 1) initial speed when deciding to join, 2) truck catch-up speed, 3) platoon speed, and 4) variation in air drag within the platoon. Results demonstrate that, within a speed range of 80–100 km/h, the platooning discriminant coefficient consistently remains greater than 0, meaning trucks benefit by joining the platoon within the critical threshold of the spatial domain. Furthermore, the platooning incentive factor exhibits an inverse relationship with the distance between trucks and platoons. Therefore, when it can join multiple platoons, a truck should join the nearest platoon for maximum platooning benefits.