Trunk cutting and welding usually occur when the vehicle needs to be repaired after a serious accident. The repair process includes cutting and welding the structural parts of the vehicle, such as the rear plate, the girder and the spare wheel chassis. Although these cutting and welding operations will not directly affect the maneuverability of the vehicle, it is classified as a major accident vehicle because it has experienced serious accidents and its structure has been repaired. This is because the cutting and welding process will have a potential impact on the structural integrity and safety of the vehicle, which requires professional maintenance and inspection to ensure that the vehicle can be restored to a safe running state.