# Full-Scale Train Derailment Testing and Analysis of Post-Derailment Behavior of Casting Bogie
## 3 Experimental Results
### Case #2 (Derailment Velocity of 55.05 km/h)  
In Case #1, the derailed wheel was not guided by the rail or containment wall. However, it was guided by the humps on the track. To identify the effects of the rail and containment wall, the derailment velocity was increased for Case #2. The target derailment velocity range was 50-55 km/h. The measured derailment speed was 55.05 km/h. Figure 23 presents the variation in the velocity and longitudinal traveling distance after derailment for Case #2. The data were obtained by the accelerometer as well as the high-speed cameras. However, the data from the high-speed cameras cannot be interpreted well after 2 s since the test bogie left the camera range due to the increased speed of the test bogie. The deceleration of the test bogie was approximately \(-1.48\) m/s\({}^{2}\). The traveling length was approximately 38 m at 3 s.  
Figure 24 shows the test bogie at derailment. It was found that the test bogie seemed to jump, bypassing the derailment device as shown in Figure 24a. Then, the front left wheel contacted with the third hump and rail fastener at 0.240 s due to the roll of the test bogie, as shown in Figure 24b. When the test bogie passed through the derailment device, the vertical acceleration in Case #2 was much greater than that in Case #1 before the first wheel contact with the track (0.242 s), as shown in Figure 24c. If higher-speed experiments are carried out, the derailment device should be improved because excessive jumping is expected.  
Figure 23: Data analysis results, Case #2: (**a**) velocity, (**b**) traveling distance.  
Figure 24: Test bogie at derailment for Case #2: (**a**) 0.124 s; (**b**) 0.242 s (first impact); (**c**) vertical acceleration when derailed (0–0.20 s).  
The main impact to the track was observed around from 0.4 s to 0.7 s, as shown in Figure 25. At 0.460 s, the front right wheel came into contact with the eighth rail fastener. Then, the front right wheel impacted the ninth hump and the rear right wheel immediately came into contact with the seventh rail fastener. The maximum vertical acceleration was found at this time, and it was approximately 3.53 g. The maximum acceleration in Case #2 was smaller than that in Case #1. This is because increased velocity is related with the longitudinal direction and vertical impact force is mainly a function of the velocity in the vertical direction.  
After 0.7 s, the test bogie ran the track with considerable lateral movement, similar to Case #1. However, for Case #2, the wheel flange was in contact with the rail as shown in Figure 26b. Then, the test bogie impacted the containment wall at 1.910 s, as shown in Figure 26c. The lateral acceleration was increased due to the impact with the rail and containment wall, as shown in Figure 26a. The lateral acceleration values were approximately 1.17 g (11.51 m/s\({}^{2}\)) and 0.75 g (7.36 m/s\({}^{2}\)) for the rail and containment wall impact, respectively. Thus, it was expected that the impact force on the containment wall would be reduced approximately 36% by the first guide by the rail for Case #2. Finally, the test bogie returned to the track center direction after containment wall impact, as shown in Figure 27.  
Figure 25: Impact of the test bogie after derailment for Case #2: (**a**) acceleration vs. time (0.4–0.7 s), (**b**) 0.460 s; (**c**) 0.534 s.  
Figure 27: Trace of the left and right wheels for Case #2.  
Figure 26: Impact of the test bogie after derailment for Case #2: (**a**) acceleration vs. time (1.7–2 s), (b) 1.780 s; (c) 1.910 s.  
As mentioned in the introduction, the basic concept of DCP type III is that the derailed train is first guided by the rail and the containment wall, preventing excessive lateral movement [8; 21; 22]. The containment wall installed in this test is DCP type III, and it was seen that the derailed train was effectively guided by DCP type III in test Case #2.