Differences between American and British railway operations and terminology.
Great Britain is a left hand country, for driving and with the railways. Directions on the railways are identified as Up (towards London) and Down (away from London). Railways continue to be measured in miles, and a mile is divided into 80 chains. A chain is 22 yards or 66 feet, one of these units of measure that one sometimes hears the existence of, but rarely sees in actual use.
In Chicago and at other major downtown stations in the United States, train departures are posted and announced by "Track Number". In Britain they use "Platform Number". But even though most platforms are actually between two tracks, two separate platform numbers are used for the two tracks.
The person operating a train is known as a "driver". While the conductor is known as a "guard".
An employee timetable is known as a "working timetable". And the special instructions is known as a "sectional appendix".
A junction station is abbreviated as "Jn.", instead of the North American "Jct."
A "Loop" line is an alternate line which diverges from a main line, and rejoins the main line at an outlying location.
Over the years, signal systems have been modernized in a fashion similar to that in the United States. Older signal systems are manual block, referred to as "absolute block" in Britain. Blocks and interlockings are controlled from signal towers, or known in Britain as "signal boxes". Modern signal systems are "track circuit block", or automatic block.
Beginning around the 1950's, signal boxes were consolidated, with the construction of newer "power signal boxes". These larger signal boxes included windows overlooking a main station controlled by the signal box. But these signal boxes would include multiple work stations, enabling remote control over longer distances. Similar to the Centralized Traffic Control systems in the United States.
In the 1980's, British Rail developed the Integrated Electronic Control Centre (IECC), as an office facility similar to the large dispatching centers in the United States. Similar is the Signalling Control Centre (SCC), established at certain locations. In recent years, Network Rail adopted the state of the art Rail Operating Centre (ROC). With a 30 year project to transition all British signal control to 12 of these regional facilities. Half of these involve upgrading of existing facilities, and half involve completely new buildings.
Signal boxes are indicated on some of the Google Maps covering London and southeast England. A simple building indicates a traditional signal box. An encased building indicates a power signal box, controlling a more widespread area. A computer screen indicates a more modern Control Centre.
Despite the adoption of these modern signal systems, bidirectional signaling is rare on multiple track lines in Britain. When one track is out of service and "single line working" is required, a "pilotman" is delegated to ride back and forth through the section and supervise movements.
Traditionally on a single track line, or "single line", the driver must be handed a "token" by the signal operator. A token dispenser would be at the signal box at each end of a segment. And these token dispensers would be electrically connected and interlocked, so that only one token could be out at a time. But newer operating methods have been developed to eliminate the use of tokens. For short branch lines, a "one train working" operating method is sometimes used.
The Signal Box
Link to an informative web site, with further information on British signaling.