Signal box
From Wikipedia, the free encyclopedia
A signal box or signal cabin is a building from which railway signals and points are controlled. Originally all signalling was done by mechanical means; cables or rods, connected at one end to the signals and turnouts and at the other to levers in the signal box, ran alongside the railway. This required signal towers to have complex arrangements of cabling, levers and pulleys. The heart of the system was the lever frame, usually fitted beneath the operating floor, which linked the levers to the external cables and rods and provided the interlocking which ensured that signals showed the correct indication with regard to the points and were operated in the right order.
Nowadays, some old-style signal cabins can still be found. Some still control mechanical points and signals. In some cases, the frame has now been removed or is out of use, and an electrical control panel has been installed. This is due to widespread power signalling. A few examples of Pneumatic signalling controlled from traditional signal cabins also exist in the United Kingdom, however these are now extremely rare. Most modern countries have little, if any, mechanical signalling remaining in the rail system.
The modern control centre has replaced widespread signal cabins. These centres, usually located near main railway stations, control the track network using computer systems. One such system is CTC, Centralised Traffic Control.
In the UK typical modern signal boxes are of the Integrated Electronic Control Centre or IECC, Entrance-Exit panel (NX) or One control switch (OCS) type. Variations of these control systems are throughout the world.
[edit] 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 |
