## 4 Discussion  
The main idea in this research is to utilize open wagons for container transportation. Experimental measures were proposed for the technical adaptation of open wagons to transport containers. We proposed the use of a special removable module, which is installed on an open wagon body, and it provides the possibility of fastening a container on it (Figure 1). The use of a rectangular profile is proposed as the profile of the removable module. To reduce the mass of the removable module, the parameters of the frame beam cross-section were optimized according to the criterion of minimum material consumption. The calculations made it possible to establish the optimal parameters of the beam cross-section of the removable module from the point of view of the minimum mass while observing the corresponding moment of resistance of its section (not lower than \(W=561.13\) cm\({}^{3}\)). Taking this into account, the mass of 1 m of the frame beam of the removable module is 45.3 kg, which is lower than the mass of a typical rectangular profile by 1.5%. The results of the strength calculations confirmed that the strength of the removable module is maintained (Figures 12 and 15). Experimental studies were conducted in order to study the strength of the open wagon body in interaction with the designed removable module. In this case, the unloading hatch cover, which forms the floor of the wagon, was subjected to testing. The results of the experimental studies confirmed the feasibility of using the removable module from the point of view of ensuring the strength of the open wagon body (Figure 22). The results of this study have advantages in comparison with the known ones. Thus, in comparison with the results of other studies [32; 33; 34], the authors proposed specific solutions for the technical adaptation of an open wagon for container transportation. Unlike in [35], the authors not only proposed a solution for the situational adaptation of an open wagon for container transportation but also provided a justification for the design of the removable module for the implementation of this solution. Unlike the technology of container transportation specified in [36], the solution proposed by the authors can be implemented by modernizing wagons and not by creating its new design. The solutions proposed in [37; 38] for improvements in wagons contribute to improving their durability in operation, but, at the same time, the authors of the specified works did not study the possibility of involving such open wagons for container transportation. The advantage of the results obtained over those specified in [39; 40; 41; 42; 43] is that the authors investigated an additional loading mode of the hatch cover. It has not been considered so far, and it was proven that its strength is ensured during container transportation. It is important to note that the use of the proposed container fastening scheme has advantages compared to existing technologies for their transportation in open wagons. The authors carried out a set of calculations of an open wagon when transporting containers considering various schemes of their interaction. The results of the calculation of the strength of the open wagon body when transporting containers on it without considering their fastening showed that the maximum stresses arise in the zone of interaction of the transverse belts of the end wall with the corner posts and are 371.3 MPa. The achieved stresses are almost twice as high as the permissible ones. The calculation of the strength of the open wagon structure was also carried out considering the fastening of containers by means of fitting stops. The maximum stresses in this case are identified in the fitting stops and they equal 142 MPa. These stresses do not exceed the values of permissible stresses. At the same time, the calculation of the strength of the container considering such a fastening scheme showed that the strength of its structure is not ensured.