An Optimal Placement of the Remote Locomotive for Minimizing Longitudinal Coupling Forces in Freight Trains

In the last years, railway research for good transportation is mainly focusing on the reduction of emissions and costs and for this reason the possibility to increase the length and the hauled mass of freight trains is studied. Since the running safety and train integrity must be always guaranteed, the control of both traction and braking phases becomes crucial. In fact, considering all the possible scenarios, sufficient power and promptness of tractive and braking actions must be always ensured. This paper investigates how the longitudinal compressive forces (LCF) are affected by the positioning of additional locomotives and wagons along the train. A simplified trainset model is used in order to estimate the maximum buffer forces during emergency braking of a set of 500 trains generated with random payload distribution. An optimisation algorithm developed for combinatorial problems is used to change the payload sequence and the position of the slave locomotive on each train, in order to minimize the buffer forces. The optimized train sequences are then analysed with a more accurate model for longitudinal trainset dynamics showing that a proper positioning of wagons and slave locos can reduce buffer forces by more than 40%.