Development of an innovative framework for the simulation of freight trains longitudinal dynamics

This paper presents SIMTRAD or SIMulation of TRAin Dynamics, an innovative framework for simulating longitudinal dynamics of freight trains. The framework integrates detailed sub-models of locomotives, wagons, couplers, and adhesion dynamics inside a modular Simulink environment, thus enabling flexible and accurate simulation of train operations. In contrast to multibody software—which mainly address the overall dynamic behaviour of railway vehicles—SIMTRAD is tailored to capture the longitudinal interactions within the train. SIMTRAD enables detailed modelling of locomotives, wagons, braking systems, and couplers, offering broad and flexible application possibilities. The proposed methodology has been validated against established software, demonstrating consistency in predicting longitudinal compressive and tensile forces acting on train couplers. A case study has also been then conducted, with the aim to optimize freight train composition by minimizing in-train forces through the optimal placement of locomotives and payload distribution. The results highlighted reductions of 53% in the values of Longitudinal Tensile Forces (LTFs) and of 7% for the Longitudinal Compression Forces (LCFs), contributing to enhanced train performance and operational efficiency. This framework also supports future integration with Hardware-in-the-Loop systems, broadening its application to different scenarios across academic research and the industrial domain related to the railway sector.