Past and present

by Sachin P Keshavan

Sachin wrote to me with an interesting insight into signalling in India. I am grateful for his permission to reproduce extracts from his interesting letter here. He would like to point out, however, that he does not claim to know all there is to know about signalling in India, and apologises if any terminology is found to be incorrect. JH

The British played a very major role in building the Indian railways. In fact most of the tracks were laid during the Raj. If you have seen any of the Indian railway stations you will clearly see the British design there (eg:- Bombay VT, Madras Central).

The signalling too was done in the British way. However the practice of semaphore signalling is slowly getting replaced with colour signalling. I clearly remember, when I was a kid, how the cabin man of our local station used to change the signals from the box. He used to literally hang on those huge iron bars. In the mid 80s the tracks close to my place (in south India) was doubled and the semaphore signalling was done away with. We now have colour light signalling.

Indian railways use a variety of blocking systems. I can name a few. It may not be technically accurate because I am not a station master or signalman.

  1. Tokenless block system: This is usually done in double line routes, and basically works like the block instruments in the UK although the instruments are of modfern manufacture. Instead of bell codes the Station Master speaks through the telephone ../../popup/photo.htmed to the instrument.
  2. Single line Tokenless block system: This is present is in single line routes. I don't know how they operate the block system, but the old practice of putting tokens in cane rings has been removed. In these routes usually the semaphore signals are replaced.
  3. Single line Token blocking: This is the practice which I like. It has all the qualities of an old Railway system. The line is single, the signals are semaphore, and then there is the passing of tokens in a cane ring which looks like a tennis racket. It is in this system that I heard about all these Neal's ball tokens, Neal's tablet tokens etc.
  4. Track circuit signalling: Thanks to this, the practice of setting up points and then changing the signals is now gone in all major stattions (at least in the main lines of the station). Now just by giving the signal on the branch line for a train to enter a main line, just the signal switch for the Home signal on the branch line, is operated, the required points are automatically set. And since the points have been set, the Home Signal on the main line cannot be altered. Now the Station Master can also get the position of the train on his signal panel.

Regarding the modernisation of Indian railways, the maximum improvement has taken place in the reservation system which is fully computerised. But in signalling etc., the method followed is still the British one, but the instruments and equipments are basically Indian. And there is also track circuiting and interlocking of signals, railway gates in major lines. Along with all these features you will be able to see a signal man at the dead of the night peeping out of his box, with the classic Indian railway signal lantern in his hand!

Many Britishers who were in India still looks upon the railway with nostalgia. Ruskin Bond (he settled in India) has written numerous stories based on the railways and the sincerity of the Indian railwayman (especially in the ranks of porters, lines men and cabin men).


Courtesy: The Hindu CHENNAI, June 23 1999.

A device, known as auxiliary warning system (AWS) is to be introduced on the Chennai Beach and Gummidipoondi section of railways for improving the passenger safety.

The main advantage of the system, stated to be the first of its kind in Southern Railway, is that trains would automatically stop if drivers jump the red signal by mistake.

At present, the system is available only in the suburban services in Mumbai. The Railway Board has sanctioned Rs. 6.45 crores for the scheme.

Sources said that there had been a tremendous increase in the traffic in the Chennai-Gummidipoondi suburban section in the past few years. In the absence of dedicated lines for the suburban services in the section, both the main line trains and EMU services had to run on the same track resulting in reduction of `"headway", the time-gap between two successive trains. Drivers operating on the section were always under pressure, as they had to stick to schedule. Even a loss of a few minutes would adversely affect the schedule and lead to dislocation of traffic.

There had been instances of drivers passing the "danger signal" inadvertently, resulting in accidents. Under the new system, while one gadget will be fitted between the tracks near the signals, another will be placed below the locos or EMU motorcars. Both the gadgets will be tuned to a particular frequency.

In case of red signal, the frequency of the equipment on the track will automatically change. If the train crosses the danger signal, the mismatch in frequency between the equipment on the track and the loco will automatically apply breaks and bring the train to a halt. There will be a monitor in the loco as well as in the EMU motor coach to alert drivers when they "jump the signal".

The system was found to be extremely successful in the Mumbai suburban service and so Railways had decided to introduce the system in all congested routes in a phased manner to improve safety, the sources said.