we recognize a goal again that might involve various agents for its satisfaction, such as on board train controllers(for control of safe acceleration), the station software(for issuing safe acceleration commands), the network communication infrastructure(for transmitting commands to train controllers rapidly), the tracking system(for keeping track of very train accurately), probably door actuators(for not opening doors if not commanded by the train controller), maybe passengers(for not forcing door opening during train moves) and so an.
again, no matter here who these agents exactly are; the point is that more or less complicated cooperation schemes are required to enforce this safety objective.