3DyFAT is the acronym and commercial name for Train Derailment Detector and Automatic Braking Device, a patent of FEVE developed thanks to the experience of FEVE from more than forty years in the railway operation and railway infrastructure administration was born 3DyFAT. 3DyFAT system is a mechanical and pneumatic device, able to instantly detect the moment at which derailment occurs, causing automatic and immediate braking of the complete train.