A system of controlling rail traffic, where (under normal operations) only one
train is allowed in the Block SectionThe section of line between one Section Signal and the next Home Signal. This term does not apply on a Track Circuit Block line. at a time. Proof of a section clearA Colour Light Signal that is displaying a Proceed Aspect or a Semaphore Signal in the Off position.
normally involves the observation of the train tail lampThe red light(s) or blind at the rear of a train to furnish evidence that the train is complete. by the SignallerA person responsible for the operation of the Signalling System, to safely control the passage and regulation of trains, usually located in a Signal Box..