Modern developments in railway signalling

The author shows that considerable developments are taking place in the use of electricity in railway signalling. Economic conditions have been responsible for the closing of many signal cabins and the substitution of electrical devices. The use of code transmission has been introduced into a number of systems for the control of signals and points, cab signals, track circuits, and train description. The mechanically interlocked lever frame is giving place to electrical interlocking, and in some cases thumb-switch control is being used. Results obtained from an economic and a reliability point of view are surveyed. In conclusion the author draws attention to the further need for track circuits and automatic train control. The symbols used are those published by the British Standards Institution¿B.S.S. 376, Parts 1 and 2¿wherever they can be made to apply.