## 4 Conclusions  
In this paper, we analyzed the functionality of DCPs installed within a track gauge through the full-scale derailment testing of freight wagon. The main conclusions drawn from this study are as follows:  
1. The derailment/collision tests showed that both the flat and container wagon continued to run along the track after derailing. That is, even if the sprung mass increases and the center of gravity position rises, the DCP type I can effectively restrain the derailed vehicle into the intended area;
2. In the case of a long vehicle such as a trailer (railway car), the collision load when the first bogie collided with the DCP was calculated from [PERSON]'s second law applying 50% of the total car mass and lateral car acceleration data;
3. The dynamic motion of the derailed vehicle was analyzed by integrating the angular velocity data obtained from the gyro sensors on the mass center of the vehicle. As the sprung mass increased (such as the difference between container wagon and flat wagon), the vehicle body behavior (roll, pitch, and yaw) after derailment was different. This was due to the change in mass and center of gravity;
4. Through the analysis of rolling behavior, it was possible to check whether the overturning phenomenon of the test car was caused by collision with DCP. Similar to a container wagon, if the total mass increases and the position of the center of gravity rises, the risk of overturning due to collision with the DCP type I may be increased compared to a flat wagon. The rolling behavior of a container wagon generated a larger rolling angle value and a larger wavelength than that of a flat wagon, but stabilized over time after collision with DCP. As a result of comparative analysis of the rolling behavior, it was judged that the DCP's function to restrain the derailed train even if the center of gravity position rises was sufficiently exhibited without any risk of overturning (rollover accident);
5. The stabilization state of the test car's vertical behavior was confirmed through the pitching behavior analysis. The overall pitching angle trend between the two wagons was similar, but it can be seen that the relatively light flat wagon's behavior in the vertical direction was unstable due to collisions with track components such as the fastener, sleeper hump, etc.;
6. Through yawing behavior analysis, it was possible to check the test car's derailment angle and to determine whether the driving direction of the derailed vehicle deviated from the intended area. Since the two wagons had the same length and width, the maximum yaw angle (derailment angle) was evaluated to be almost identical. Then the yawing angles of both wagons quickly approached zero. That is, it can be seen that the derailed vehicle gradually moved along the track due to the restraint effect of the DCP type I.  
Our research team plans to verify the previously developed simplified FE model based on the experimental results of this and companion papers, and we intend to develop the design specification for DCPs.  
**Author Contributions:** Conceptualization, N.-H.L.; Data curation, H.-U.B. and K.-J.K.; Funding acquisition, N.-H.L.; Investigation, H.-U.B., K.-J.K., S.-Y.P., J.-J.-H. and J.-C.P.; Project administration, N.-H.L.; Supervision, N.-H.L.; Validation, N.-H.L.; Writing--original draft, H.-U.B. and N.-H.L.; Writing--review & editing, N.-H.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was supported by a grant (RS-2021-KA163289) funded by the Ministry of Land, Infrastructure, and Transport of the Korean government.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest.