Computer-based interlocking is

railway signal A railway signal is a visual display device that conveys instructions or provides warning of instructions regarding the driver's authority to proceed. The driver interprets the signal's indication and acts accordingly. Typically, a signal migh ...

interlocking implemented with

computer A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...

s, rather than using older technologies such as relays or

mechanics Mechanics () is the area of physics concerned with the relationships between force, matter, and motion among Physical object, physical objects. Forces applied to objects may result in Displacement (vector), displacements, which are changes of ...

General

CBIs are mostly implemented in two parts; a section that implements the safety and failsafe requirements, and a second section that implements "non-vital" controls and indications. The European Union is working towards an EU standard within this area, called

ERTMS The European Rail Traffic Management System (ERTMS) is the system of standards for management and interoperation of signalling for railways by the European Union (EU). It is conducted by the European Union Agency for Railways (ERA) and is the o ...

Brands

Different manufacturers have their own brands of CBI such as * SSI (Solid State Interlocking) - BR,

Invensys Invensys Limited was a multinational engineering and information technology company headquartered in London, United Kingdom. At its height, the company had offices in more than 50 countries and its products were sold in around 180 countries. I ...

, GEC-General Signal * Microlok II * Smartlock *

Westlock Westlock is a town in central Alberta, Canada. Founded in 1913, the town is primarily an agricultural, business, and government administration centre serving communities and rural areas within surrounding Westlock County. Geography Westlock ...

* Germany - Alister CBI from Funkwerk IT

Railway Gazette International ''Railway Gazette International'' is a British monthly business magazine and news website covering the railway, metro, light rail and tram industries worldwide. Available by annual subscription, the magazine is read in over 140 countries by tran ...

of July 2012, page 18

Interface between different brands

When interfacing different brands of CBI equipment, it may be necessary to use relays of each regime, which are then hardwired from one to the other. This happens in the middle of the

Channel Tunnel The Channel Tunnel (), sometimes referred to by the Portmanteau, portmanteau Chunnel, is a undersea railway tunnel, opened in 1994, that connects Folkestone (Kent, England) with Coquelles (Pas-de-Calais, France) beneath the English Channel at ...

where French and British signalling equipment meet.

Competition Rules

Since only some of the major signalling organisations make CBI equipment, it was agreed that to prevent other players being left out in the cold, CBI equipment would be made available to those players at cost.

References

Interlocking systems Rail infrastructure {{rail-transport-stub