## 3 Experimental Results
### Change in Center of Gravity  
In order to evaluate the effectiveness of the DCP function according to the increase in the vehicle's center of gravity, the additional experiment was conducted with a container wagon. The container wagon weighed 42 kN more than the flat wagon and had a center of gravity 407 mm higher than the flat wagon.  
The speed of the container wagon measured just before the derailment was 46.69 km/h. As shown in Figure 15, the wheels were effectively guided by the DCP within the track gauge after derailment and were running within the track area. Figure 16 shows the damage condition of DCP at the point of derailment, and although some components at the edges of the DCP side were damaged, we conclude that the DCP effectively performed lateral deviation guiding of the derailed wheels without significant issues. In rare cases, however, if the subsequent train causes continuous repeated collisions at the same damage location, the degree of breakage may be greater, which may lead to a reduction in the DCP containment performance. In order to cover the concerns related to these rare events, additional protection facilities such as DCP type II or III are required. In addition, after a derailment accident occurs, it is recommended to evaluate the condition of the damaged DCP panel and replace some damaged DCP panels according to the result.  
Figure 14: Collision load of the wheels of the flat wagon.  
Figure 15: Post-derailment behavior of the container wagon (side view).  
In order to evaluate the effectiveness of the DCP function according to the increase in the center of gravity, the behavioral characteristics of the flat wagon and the container wagon after derailment were compared. For comparison, the dynamic behavior of the test car considered rolling, pitching, and yawing as shown in Figure 17.  
Figure 18 shows the angle change of the flat and container wagon after derailment. The vehicle angle can be obtained by integrating the angular velocity data measured during the experiment. Figure 18a shows the rolling angle of a flat wagon and a container wagon. Through the analysis of the rolling behavior, it was possible to determine whether the wagon's overturning phenomenon occurred due to a collision with the DCP. The rolling behavior of the container wagon was larger than that of the flat wagon as it swung in the left and right directions of the running direction, but it can be seen that it gradually stabilized without the overturning phenomenon.  
Figure 16: Damage status of DCP after collision.  
Figure 17: Dynamic behavior of the vehicle.  
The pitching angle of a flat and container wagon is shown in Figure 18b. The derailed flat wagon oscillated up and down as it continuously collided with track structures such as  
Figure 18: Comparison of vehicle angles after derailment: (**a**) rolling behavior, (**b**) pitching behavior, and (**c**) yawing behavior.  
sleepers. However, the container wagon, which was heavier than the flat wagon, showed a stabilized pitching behavior even after derailment.  
The yawing angle is shown in Figure 18c. The overall length of the container and flat wagon was the same, so when the front bogie collided with the DCP, the yaw angle was equal to about 2.8 degrees. After the derailment of the rear bogie, the yaw angle of the flat and container wagon converged to almost 0 degrees. The slight difference in angle is believed to have been due to the speed and weight difference.