# Full-Scale Train Derailment Testing and Analysis of Post-Derailment Behavior of Casting Bogie
## 3 Experimental Results
### Case #1 (Derailment Velocity of 28.08 km/h)  
For Case #1, the target speed range was 25-30 km/h. The measured derailment velocity was 28.08 km/h. Figure 16 shows a front view of the post-derailment behavior in Case #1. It can be seen that the bogie ran in the right lateral direction after derailment (0.410-1.810 s), and the left wheel continuously contacted the hump of the concrete track (1.810-3.570 s). Then, the bogie moved to the left direction without contact between the right rail and left wheel (3.570-5.630 s). The direction was changed due to the effect of the hump in this case. In this study, the Rheda 2000 type concrete track was used, and the hump in this track affected the post-derailment behavior. The acceleration data were analyzed to calculate the velocity and traveling distance of the test bogie. The analysis results were compared with the results obtained in the image data from the high-speed cameras for cross-validation of the data. It is known that the image analysis offers a certain potential for the dynamic investigation [20]. The velocity and traveling distance of the test bogie were also calculated by target mark tracking from the image data, as shown in Figure 17. The results are shown in Figure 18 as a solid line. It can be seen that the velocity obtained from the high-speed camera showed initial fluctuation. However, the overall trend of the velocity was similar to that from the  
Figure 15: Examples of running diagrams of the power car. accelerometer. The velocity decreased almost linearly, as shown in Figure 18a. The slope of Figure 18a represents the deceleration, and it was approximately \(-0.97\) m/s\({}^{2}\). By integrating the acceleration data twice, the traveling distance could be calculated, as shown in Figure 18b. The traveling distances obtained from the accelerometer and high-speed cameras were similar to each other. The discrepancy may come from accumulated error during the integration or distortion of the image by the use of a wide-angle lens. Figure 16: Post-derailment behavior of the bogie for Case #1, front view. The longitudinal, lateral, and vertical acceleration data of the test bogie were analyzed with the video images together. The first impact was observed at 0.410 s after derailment, as shown in Figure 19. It can be seen that there were sudden changes in acceleration at the time of the first impact, as shown in Figure 19a. The maximum acceleration was found in the vertical direction, and it was 5.07 g (49.78 m/s\({}^{2}\)). If the total mass of the bogie is included in the calculation of the impact force, it is equivalent to approximately 207 kN of impact force. The first impact occurred between the left wheel and hump, as shown in Figure 19b. Figure 19c shows the damage to the hump and rail fastener due to the first impact. Figure 19: First impact, Case #1: (**a**) acceleration vs. time (0.3–0.6 s); (**b**) test bogie at first impact; (**c**) damage to the hump and rail fastener due to the first impact. Figure 17: Example of image analysis by target mark tracking. Figure 18: Data analysis results, Case #1: (**a**) velocity, (**b**) traveling distance. Similar to Figure 19, information about the second and third impacts is presented in Figure 20. The second and third impacts were observed at 0.750 s and 0.810 s, respectively. In the second impact, the right and left rear wheels impacted the fourth hump, as shown in Figure 20b,c. The maximum vertical acceleration was approximately 5.57 g--larger than that from the first impact. This may be attributed to the pitching moment of the bogie after the first impact. In the case of the third impact, the front right wheel contacted the sixth and seventh humps in succession. At the third impact, the peak of the vertical acceleration was markedly decreased. After the third impact, the test bogie ran the track without any further significant impact with track components. However, considerable lateral displacement was observed.