Numerical investigation on the dynamic behaviour of derailed railway vehicles protected by guard rail

Train derailment can cause not only damage to the train itself but also secondary damage to surrounding structures. For this reason, guard rails are commonly used to prevent secondary damage caused by derailed trains on high-risk lines. In this paper, a 3D vehicle-track dynamics simulation model and a collision contact model were used to investigate the post-derailment dynamic behaviours of the train as well as the effectiveness of guard rail protections. Variables studied include derailer oblique angle, the gap between running rail and guard rail, the effect of derailing speed on the posture, and impact force after derailment. The study shows that the oblique angle has a strong influence on the dynamic derailment behaviours. At a large gap, the bogie generates a noticeable distortion, which is very detrimental to the derailed vehicles. It was found that when the gap is 200 mm, the derailed wheelsets roll on the sleepers stably. And high derailing speeds can also cause significant impact forces. These simulations further the theory of train running posture and impact response, and can inform good railway design and maintenance. This is particularly true for tracks on which guard rails are installed to reduce secondary damage.