Indian railways, other Networks 

From an operational point of view, the Indian Railways have been divided into various hierarchies viz the railway board, zone and division. The division is the primary unit, which deals with day-to-day train operations. Each division has many section controls, having jurisdiction over 150 to 200 km. The section controller requires communication with each station, called section control communication for real-time controlling and monitoring of train operations. A telecom Network is also required for the flow of the administrative instructions between the various hierarchies of the railways.

The railways' telecom requirements can be categorized as follows.

Control communication: For controlling the movement of the trains. The control communication is between the section controller and each station in his jurisdiction. 

Administrative communication: For monitoring the operations and flow of administrative instructions. The major activity centers and the headquarter offices like the railway board, zonal railways headquarter, production units, divisions, etc are connected with each other. This is provided with the help of the telephone exchanges-connecting them through a microwave Network. 

Emergency communication: For the communication between the train crew and the section controller for reporting emergencies, etc. 

The railway requirement for control and emergency communication is both unique and exclusive. Presently, the control communication is working either on an overhead alignment or underground copper cables, which also carry the vital block circuits. The block circuits are vital circuits, as these circuits ensure that only one train enters the block section at a time.

Besides the emergency communication through which the crew reports emergencies to the section controllers, are also the vital circuits. Emergencies like disruption of traffic; accidents, etc are reported through the administrative circuits to the divisional and zonal headquarters, railway board and others for taking corrective action.

The Radio Network

The railways have been installing the microwave Network for long distance communication, primarily used for administrative communication. In addition, the availability of the microwave link has also made it possible to use the links for providing radio patching in the control circuits.

For their microwave Network, the railways have been allotted a 300 MHz slot in 7 GHz band. The old analog microwave Network, having served its useful life, is being replaced by a state-of-the-art digital microwave system. 

The Indian Railways had been facing acute problems in control communication, especially in the eastern sectors, due to the frequent theft of underground copper cable, which was used for the train control communication. The Howrah-Mughalsarai section on the eastern railway is an important section linking both the eastern and the northern regions. The density of the trains in the section is very high and an interruption in the communication circuits adversely affects the railway operations.

Hence, the railways have decided to use the 18 GHz frequency band for providing control communication on which the vital block circuits are also working. The 1,000-km long link in this section is probably the longest 18 GHz link working in tandem.

Passenger Safety

The utility of providing communication to the crew of the train is undisputed, as far as the safety and efficiency of the train operation is concerned. The railways are still using a primitive mode of communication for this purpose. The crew is provided with a portable emergency control phone, which can be hooked on to overhead alignment in a non-electrified territory or connected to sockets in an electrified territory to talk to the controllers. However, in this arrangement, the controller or stationmaster is unable to contact the crew when required. Besides, the crewmembers are also not able to speak to each other. To overcome these difficulties, the following steps have been taken:

Provision of walkie-talkie sets to the drivers and guards: 5 watt walkie-talkie sets are being provided to drivers and guards of trains for communication in a static mode, during emergencies like train parting, rolling stock, pulling of the alarm chain, etc. The walkie-talkie sets have already been provided to the drivers and guards of all mail/express/passenger trains. 

The mobile train radio communication: It has already been decided to provide the Mobile Train Radio Communication (MTRC) system on important routes where the mail/express trains are running and the sectional speed is very high. The MTRC system enables the establishment of communication in a duplex mode-where both the parties can talk simultaneously-between the driver and the guard and between the driver/guard and the nearest station/control office.

Source: Akhil Agarwal 

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