A system and a method for initiating an emergency braking of a guided vehicle, where the system is configured for cooperating with a braking system of the guided vehicle. The system includes a processing unit configured for initiating the emergency braking if it detects that a guided vehicle speed V at a guided vehicle position X exceeds a speed limit V.sub.limit that is defined for the position X in order to ensure that a speed V.sub.0 is reached at a final position X.sub.0 located upfront the guided vehicle on a route followed by the guided vehicle. The processing unit of the system is configured for automatically determining the speed limit V.sub.limit for the position X from an emergency brake rate function which varies in dependence on the guided vehicle speed at a remarkable position P.sub.j.