A signal box or signal cabin is a building from which railway signals and points are controlled. In Architecture, Construction, Engineering and real estate development the word building may refer to one of the following Any man-made A signal is a mechanical or electrical device erected beside a Railway line to pass information relating to the state of the line ahead to train drivers/engineers. This article primarily uses North American terminology British and Commonwealth terms are given in parentheses The term signal cabin is used in Ireland, parts of Scotland and in Australia. In North America, the somewhat equivalent term interlocking tower is used.
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History
Originally, all signalling was done by mechanical means. A machine is any device that uses Energy to perform some activity Points and signals were operated locally from individual levers or handles, meaning that the signalman had to walk between the various pieces of equipment to set them in the required position for each train that passed. A signalman or signaller is an employee of a Railway transport network who operates the points and signals from a Signal box in order Before long, it was realised that control should be concentrated into one building, which came to be known as a signal box.
Control apparatus
Lever frame
The earliest signal boxes housed mechanical lever frames. Mechanical Railway signalling installations rely on lever frames for their operation to interlock the signals and points to allow the safe operation The frame was usually mounted on a beam beneath the operating floor. Interlocking was attached to the levers, which ensured that signals showed the correct indication with regard to the points and were operated in the right order. In Railway signaling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings Wires or rods, connected at one end to the signals and points and at the other to levers in the signal box, ran alongside the railway.
Levers are painted according to their function, e. g. red for stop signals and black for points, and are usually numbered, from left to right, for identification. In most cases, a diagram of the track and signalling layout is mounted above the lever frame, showing the relevant lever numbers adjacent to the signals and points.
Power frames have miniature levers and control the signals and points electrically. In some cases, the interlocking was still done mechanically, but in others, electric lever locks were used.
In a few cases, signals and points were operated pneumatically upon operation of the appropriate lever or slide.
Control panel
In a signal box with a control panel, the levers are replaced by buttons or switches, usually appropriately positioned directly onto the track diagram. These buttons or switches are interfaced with an electrical or electronic interlocking. In the UK, control panels are of the following types:
- Individual Function Switch (IFS)
- A separate button/switch is provided for each signal and for each set of points. This type of panel is operated in a similar manner to a lever frame. The signalman must move each set of points to the desired position before operating the switch or button of the signal reading over them.
- This type of panel needs the least complex circuitry but is not suited to controlling large or busy areas.
- One Control Switch (OCS)
- A separate switch/button is provided for every signalled route. There will be as many switches/buttons per signal as there are routes (i. e. signalled destinations) from that signal. To set the desired route, the relevant switch or button is operated. All points within the route are automatically set to the required position.
- Individual points switches are provided, but they are normally left in the central position, which allows the points to be automatically set by the action of setting a route.
- Entrance-Exit (NX)
- This type of panel has one switch/button provided for every signalled route (except that some panels have separate 'entrance' and 'exit' devices). To set a route, the signalman operates the device for the 'entrance' signal, followed by the device for the 'exit' (destination) signal. All points within the route are automatically set to the required position and, provided all the points are detected by the interlocking in the correct position the signal will clear.
- Individual points switches are provided, but they are normally left in the central position, which allows the points to be automatically set to the normal or reverse position by the action of setting a route.
Similar principles of operation as described above are applicable throughout the world.
Visual Display Unit
Modern signal boxes nowadays tend to be provided with VDU based, or similar, control systems. A visual display unit, often called simply a monitor or display, is a piece of Electrical equipment which displays images generated from the Video These systems are less expensive to build and easier to alter than a traditional panel. In the UK, large modern signal boxes are typically of the Integrated Electronic Control Centre type. Integrated Electronic Control Centre ( IECC) was developed in the late 1980s by the British Rail Research Division for UK-based Railway signalling centres Variations of these control systems are used throughout the world.
Present day
Nowadays, some old-style signal boxes can still be found. Petersfield railway station is a Railway station serving the Market town of Petersfield Hampshire, England. Some still control mechanical points and signals, although in many cases, the lever frame has been removed or is out of use, and a control panel has been installed. Most modern countries have little, if any, mechanical signalling remaining on the rail system. Both in the UK and Ireland, however, mechanical signalling is still surprisingly common away from the busiest lines.
The modern control centre has largely replaced widespread signal cabins. These centres, usually located near main railway stations, control the track network using electrical or electronic systems. |}A train station, railway station, railroad station, or station yard is a facility at which Passengers may board and alight from Trains One such system is CTC, Centralised Traffic Control. Centralized traffic control ( CTC) is a signalling system used by Railroads The system consists of a centralized Train dispatcher 's office
References
- Kichenside, G. and Williams, A. , (1998), Two Centuries of Railway Signalling, Oxford Publishing Co. , ISBN 0-86093-541-8
- Vanns, M. A. , (1995), Signalling in the Age of Steam, Ian Allan, ISBN 0-71102-350-6
See also
External links
- The Signal Box
- Over 100 photographs of traditional mechanical signal boxes on Britain's rail network
- A large photograph collection of operational and non-operational boxes remaining in the United Kingdom
Photo gallery
 Signal levers, Switzerland |
 A traditional UK signal box |
 Inside a signal box on the Isle of Wight Steam Railway |
 A disused signal box at Patrickswell, County Limerick, Ireland |
 Walton Street Crossing Box, Hull, Humberside, England. Area Signalling Centre (ASC is a British term used to describe a modern Railway Signal box that controls a large area The Isle of Wight Steam Railway is a Heritage railway on the Isle of Wight. Patrickswell ( Tobar Phádraig in Irish) is a small town in County Limerick, Ireland. County Limerick ( Contae Luimnigh in Irish) is a County in the Province of Munster, located in the mid-west of Ireland with County Ireland (pronounced /ˈaɾlənd/ Éire) is the third largest island in Europe, and the twentieth-largest island in the world Kingston upon Hull ( almost invariably referred |
 An active signal cabin at Shaw and Crompton railway station, in Greater Manchester, England. Shaw and Crompton railway station is a railway station located in Shaw and Crompton, within the Metropolitan Borough of Oldham, Greater Manchester, Greater Manchester is a Metropolitan county in North West England, with a population of 2 |
 A disused signal box at Liverpool Street station |
 Chappel South box at The East Anglian Railway Museum |
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