release

A release is a physical authorization document used in railway block systems to permit a train to proceed into the next block section when no telegraph or signal apparatus exists at an intermediate siding. It functions as a manual substitute for the electrical or mechanical block signaling that protects main lines, allowing safe train following by documented handoff rather than automatic means.

The release card itself is a standardized printed form carried by the train crew, typically the driver or conductor. It contains specific information about the block section ahead: the block number or identifier, the date and time of issue, the name of the siding or station where it was issued, and clear instructions on speed restrictions or conditional movements. The card serves as proof that the train has been cleared to enter that particular block and that no conflicting train occupies it at the moment of issue.

Use in non-telegraphed sidings

Intermediate sidings without telegraph facilities operate under release authority because they lack the communication infrastructure to send advance notice of train movements. A signaler or station staff member at a staffed location physically hands the release to an approaching train or a previous train delivers it to the next crew. This creates a chain of custody: each crew member is personally responsible for the card and the information it carries. The system depends entirely on human communication and accurate record-keeping of which train holds which release at any given time.

Releases carry significant operational risk when trains follow closely in the same block. If a release is issued incorrectly, withheld, or misunderstood, two trains can legally enter the same section. Most release systems therefore included written protocols requiring minimum time intervals or physical verification of the preceding train's clearance before issuing the next release. The practice declined as continuous track circuits and automatic signaling replaced manual block methods on busy lines.

The term reflects its primary function: it is the document that releases a train from the stopping point of one siding, granting it movement rights into the protected section ahead. Release cards remain in use on heritage railways, industrial branch lines, and some heritage or light railway systems where full signaling infrastructure is not economically justified.