Freight trains for intermodal transportation: optimisation of payload distribution for reducing longitudinal coupling forces

Increasing the length and hauled mass represents an effective method for boosting freight train transportation. However, several analyses showed that longer and heavier trains pose safety concerns mainly related to large buffer forces generated during emergency braking. The paper investigates the effect of payload sequence on these forces referring to freight trains for intermodal transportation. A simplified trainset model is developed to predict the maximum buffer forces during emergency braking, for a set of 500 trains generated with random payload distribution. An optimisation algorithm developed for combinatorial problems is then applied to change the payload sequence on each train so that buffer forces are minimised. Optimised train sequences are then inputted into a more accurate model for longitudinal trainset dynamics, showing that a proper wagon arrangement can decrease buffer forces by more than 40%. The analysis also provided general guidelines for optimising wagon sequence.