The assessment of safety against freight wagons derailment is a mandatory element of the documents provided to the EU notifying authorities for the entry into service of new freight wagons. The assessment methodology is presented in EN 14363:2016. It is mainly aimed at experimental measurement of certain parameters and the data are used to calculate the safety criterion. The practical implementation of the tests is accompanied by many difficulties: finding a track with a proper radius, ensuring free access to the railway infrastructure for a long period of time, waiting for suitable metrological conditions, preparation of the curve and the test wagon etc. These difficulties are well known to the European legislators, and as a solution they propose a large set of reference wagons that have undergone real tests. It is sufficient to demonstrate that the parameters of the new wagon relate to some of reference wagon parameters to avoid such a requirement. Proving the "convergence" of the parameters of the new and the reference wagons is a lengthy, complex and, in many cases, subjective process. To introduce an objective assessment, the authors set themselves the task of developing a theoretical method for assessment of safety against derailment.

The study proposes a theoretical method for evaluating the 'safety against derailment' indicator of a specialized train composition for the transportation of very long rails. A composition of nine wagons, suitable for the transportation of rails with a length of 120 m, is considered. For the remaining recommended rail lengths, the number of wagons is reduced or increased, the method being modified depending on the required configuration. In accordance with the requirements of EN 14363:2019, the composition is in a curve with a radius of R=150 m. The rails bend, some of them contact the vertical stanchions of the wagon and cause additional transverse forces, which are balanced in the rail track. This is a prerequisite for derailment of the vehicle. The goal of the study is to determine the additional transverse forces that arise because of the bent rails. The task is statically indeterminate, and considering the dimensions of the rails, its solution becomes seriously difficult. For the purposes of the study, the finite element method was used. Based on the displacements of the support points of the rails (caused by the geometry of the curve) the bending line of the elastic load is determined and the forces in the supports are calculated. A group of five rails is considered, with results multiplied proportionally for cases other than five. The resulting forces are considered when determining the derailment safety criterion defined by EN 14363:2019.