Purpose. This study is aimed at highlighting the features of determining the longitudinal load of the supporting structure of a flat car loaded with a piggyback under operating conditions and substantiating the possibility of using a flat car model 13-401 for transportation of piggyback. Methodology. Mathematical modeling of the dynamic loading of the supporting structure of a flat car model 13-401 loaded with a piggyback was carried out. Two schemes of interaction between the piggyback and the supporting structure of the flat car are taken into account: the lack of movements of the piggyback relative to the frame of the flat car during movement and the presence of movements of the piggyback relative to the frame of the flat car during movement. Solution of the differential equations is implemented in the MathCad software. The obtained accelerations were taken into account motion when calculating the strength of the supporting structure of the platform car. The strength calculation of the supporting structure of the platform car was carried out. Obtained accelerations are taken into account to calculate the strength of supporting structure of the flat car. Findings. Based on the mathematical modeling of the dynamic loading of supporting structure of the flat car, it was found that in the absence of piggyback movements relative to the flat car frame, the maximum acceleration was 32 m/sec². If the piggyback moves relative to the flat car frame, the maximum acceleration acting on the supporting structure is about 40 m/sec², and about 42 m/sec² on the piggyback. The main strength indicators of the supporting structure of the flat car are determined. It was established that the maximum equivalent stresses in this case arise in the cantilever parts of the center sill and are about 315 MPa, that is, do not exceed the permissible ones. The maximum displacements in the structure nodes are 2.6 mm, the maximum deformations are 2.5 ∙ 10^-2. Originality. The mathematical model of the dynamic loading of supporting structure of a flatcar loaded with a piggyback is improved. At the same time, the rigid piggyback fastening to the flat car frame, as well as the flexible one, is taken into account. For the first time, a computer model has been developed to determine the strength of the supporting structure of a flat car during the piggyback transportation. The model makes it possible to determine the strength main indicators of supporting structure with its longitudinal loading. Practical value. The conducted studies allow us to conclude that the transportation of piggyback on the flat car model 13-401 is possible. The results of the studies will contribute to the creation of recommendations on the flat car design for piggyback transportation, and can also be useful developments when creating removable means of piggyback transportation.

Introduction. The priority area of transport systems development is the formation of transport corridors with multimodal systems and intermodal cargo delivery technologies, ensuring the achievement of economic, social and environmental goals facing the countries. For the transport system of Russia, which claims to advance transit cargo flows through its territory, the solution to the above problems can be achieved by organization of the piggyback transportation. A necessary condition for the organization of effective piggyback transportation in domestic and international traffics is the systematization of parameters and the assessment of technical compatibility of the involved rolling-stock.Methods and models. A systems approach is used to represent piggyback transportation as a complex technical system consisting of road vehicles, domestic and foreign railway rolling-stock interacting in intermodal terminals. The ER-model is used to describe the conceptual scheme of the piggyback system.Results. The parameters of the road and railway rolling-stock are justified and systematized, their mutual influence is determined at the level of compatibility of their technical and operational parameters in the organization of domestic and international piggyback transportation. Systematization, structuring, storing and updating of rollingstock parameters are carried out using the database «Determining the rolling-stock basic parameters of piggyback delivery systems» developed in Microsoft Access.Conclusion. The developed system of parameters allows to assess technical compatibility of road and railway rolling-stock of the countries participating in piggyback transportation, and can also be used for unification of intermodal transport units and harmonization of the overall weight restrictions on the road and railway networks.Financial transparency: the authors have no financial interest in the presented materials or methods. There is no conflict of interest.