Railroad signaling and train control

EFFICIENCY of train operation depends largely upon a system of directing train movements that will insure the maximum utilization of track and equipment capacity and the maximum output of train miles in a unit of time. In the earlier days the time interval method of railway signaling was favored, movements being directed by timetables and train orders. The space interval method is now universally recognized as most satisfactory, train movements being directed by block signals in addition to timetables and train orders. Block signals may be operated manually or automatically by means of a track circuit, the shunting of which by the trains operating upon the rails actuates the apparatus.