A system under which train or engine movements are authorized by block signals whose indications supersede the superiority of trains for both opposing and following movements on the same track.
A term applied to a system of railroad operation by means of which the movement of trains over routes and through blocks on a designated section of track or tracks is directed by signals controlled from a designated section of track or tracks without requiring the use of train orders and without the superiority of trains.
Centralized traffic control (CTC) is a signalling system used by railroads. The system consists of a centralized train dispatcher's office that controls railroad switches in the CTC territory and the signals that railroad engineers must obey in order to keep the railroad's traffic moving safely and smoothly across the railroad. In the dispatcher's office is a graphical depiction of the railroad on which the dispatcher can keep track of trains' locations across the territory that the dispatcher controls.
