Signalling: A Critical Element in Indian Railway


One hundred and twenty thousand kilometres of track, sixty-seven thousand kilometres in route length; those figures are the lengths of tracks that run in India. Staggering numbers like these have a multitude of pros and cons. Some of the advantages to such enormous track length are that there are rarely any places which aren’t covered by the railways. From the mountains of the Himalayas to the dry deserts of Rajasthan and from the Western Ghats to the Valleys and hills of the Northeast; there are no places the railroads cannot reach.

Such far-reaching tracks mean there are obstacles everywhere. Fog, rain, dust storms, and a host of other weather problems can create havoc for trains and their schedule. The IR, although is relatively old, has recently upgraded various technologies to keep the safety standards for railroads in check.

The IR incorporates a variety of methods to manage its train operations based on traffic density and safety methods, which include many signalling technologies.

Recent reports from 2017, suggest nearly 2,850 km of track uses automatic block signalling for train operations- concentrated in high-density routes, junctions and most importantly large cities. The remaining routes use absolute block signally, where trains are controlled manually by signalmen, sitting in signal boxes which are located in the stations. Some lesser known and used routes still employ the usage of manual block signalling, which uses tokens exchanged physically as a means of communication. There are still far advanced methods like intermediate block signalling, which is cheaper but more effective and is employed in 501 blocks across India.

The IR uses coloured signal lights, which replaced cruder and older semaphores and disk-based signalling which was dependant on position and colour. IR deploys a system with two-aspect, three-aspect and four or multiple aspect signalling across its network. Signals at most places are interlocked using panel interlocking, route relay interlocking or electronic interlocking; these methods are devoid of any human signalling error. They also utilize track circuiting and block proving axel counters for better train detection, thus leading to safer tracks.

As of 2017, 90% of all stations that have broad gauge tracks, employ the usage of multi-aspect signalling and are interlocked stations. Around 99% of all the key routes (A, B, C or D) have track circuitry and block proving axel counters for automated train detection. The IR also has nearly 51,000 kilometres of Optical Fibre Cable (OFC) network; used for communication, train control and data exchange. Nearly 2500 kilometres of the whole route is covered by GSM-R based mobile train radio communications system.

At the end of 2017, the IR announced that it will implement ETCS level 2 systems for signalling and control, on very important routes with an investment of 2 billion dollars. Currently, only one sector on IR, the Kanpur-Ghaziabad route uses a centralized traffic control system. A real-time tracking system is also used by the suburban trains of Kolkata and Mumbai.

Train enquiry seat availability and much more can be found on the IR website and other private websites also, which also has detailed info-graphics on this topic and more.


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