Cab signalling

Cab signalling uses modulated frequencies driving the track circuits to transmit to the driving cabin of a train information about the status of the signal ahead, whether it is green, yellow or red. The first such systems were installed in the 1920's in the US, and later in Holland in the 1940's.

High speed trains such those in Japan, France and Germany use such systems in principal, though they may be mutually incompatible in practice.

See Also

• Automatic Warning System
• Automatic train protection