# Full-Scale Train Derailment Testing and Analysis of Post-Derailment Behavior of Casting Bogie
## 1 Introduction  
In Korea, there were 33 train accident cases in total during the five-year period 2012-2016. Among these, derailment accidents accounted for 78.8% (26 cases) [1], and derailment occurred more often than other types of train accidents. Derailment accidents can cause catastrophic damage to a community. It is hard to prevent 100% of derailment accidents since there are always unexpected factors that can cause derailment, such as human error and natural disasters. Thus, it is necessary to develop technology to reduce damage due to derailment. This technology can be categorized as derailment protection [2; 3; 4].  
To reduce the damage from derailment accidents, protection facilities can be installed in the railway track. In Korea, guard rails to prevent derailment are used at sharp curves, bridges, and switches, as shown in Figure 0(a). Containment walls are also installed on bridges for high-speed railways (where the minimum speed of the line is 200 km/h), as shown in Figure 0(b) [5; 6; 7].  
In European countries, three different types of derailment containment provisions (DCPs) are used (DCP types I, II, and III), as shown in Figure 2(a). The guard rail is one example of a DCP type I facility, where the DCP is installed inside the track gauge. The wheel of the derailed train comes into direct contact with the facility. DCP type II is similar to DCP type I, but is installed outside of the track gauge. DCP type III facilities are installed outside of the track, similar to DCP type II. However, they are different from DCP type II since the axis of the wheel or bogie of the derailed train impacts this type of DCP.  
To verify the performance of such derailment protection facilities, tests and simulations must be conducted, including investigation of the post-derailment behavior of the train. Some researchers have conducted derailment and post-derailment simulations by using 3D finite element analysis. Researchers in Sweden [9; 10] analyzed the post-derailment behavior of the wheel of a derailed train colliding with a concrete railroad sleeper. Some researchers in China [11; 12; 13] investigated the post-derailment dynamic behavior of a railway vehicle under earthquake excitations. Also, there have been studies simulating collision with a protective facility after the derailment of a high-speed train [2; 3; 4].  
Figure 1: Examples of derailment protection facilities: (**a**) guard rail and (**b**) containment wall.  
Figure 2: Concept of derailment containment provisions (DCPs).  
Full-scale derailment testing is the most reliable method to evaluate the post-derailment behavior of a train and the performance of derailment protection facilities. However, it is very difficult, and only a few such studies can be found in the literature. [PERSON] et al. [14] performed derailment testing, but it was lab-scale testing and the speed was limited to 16 km/h. The test methods relating to train derailment, such as the derailing method and data filtering, are not well established and must be investigated.  
In this study, full-scale train derailment testing was conducted. For realistic simulation of the derailment situation and reliable data acquisition from the test, a derailment device and data acquisition system were proposed. Then, from the test, the post-derailment behavior of the train was analyzed.