TRAIN PROTECTION AND WARNING SYSTEM

Train Protection and Warning System (TPWS) is a safety system designed to eliminate accidents caused by human errors such as passing signal at danger and over speeding. Although a rudimentary form of TPWS called the Auxiliary Warning System has been in use in Western Railway since 1987, the Railway Board, considering the substantial upgradation of technology that has taken place since then, decided to adopt the multiple vendor non-proprietary European Rail Traffic Management System/European Train Control System which is in use for the high speed networks of European Railways for the pilot project of Southern Railway.

The increase in suburban traffic in metropolitan areas has necessitated an increase in the alertness and concentration of the motormen as they operate suburban EMU trains. Southern Railway has implemented a pilot project of the TPWS on the Chennai Central/Chennai Beach to Gummidipundi section at a cost of Rs.46 crores.

Train Protection and Warning System acts on the principle of interfacing the aspect of the signal ahead and communicating to the driver the safe distance the train can travel till a danger signal is encountered. It also has speed supervision over the driver and applies brakes whenever the driver exceeds the permissible speed. It has danger signal protection and applies emergency brake wheneverthetrain passes thesignal at DangerorRed.
TPWS was successfully commissioned on 02.05.2008 by the Hon'ble Union Minister of State for Railways Shri R. Velu in Chennai division; it covers the section between Chennai Central/Chennai Beach to Gummidipundi for a distance of 50 km on Chennai Central - New Delhi double lineAutomaticsection.

The track side parameters like gradient, permanent speed restrictions and signal aspects are conveyed by means of track magnets called Balise. The signals are picked up by antennas which are located at the motor coaches in EMUs for sending signals to the On Board Computer (OBC). The OBC also activitates and updates the periodical information in the form of speed and distance the train is permitted to travel. Audio visual information is displayed in the Simplified Driver Machine Interface (SDMI) which is kept on the driver's desk. SDM\i%7a'ofdsDoZZaTo)hme The actual speed of the train is calculated by means of axle mounted speed sensors. The various important train parameters like load of the train, train length, rate of deceleration are fed into the OBC.

While approaching a signal which is at danger, the driver is expected to bring the speed of the train down to a suitable level in advance of the signal. In case he does not, the system is activated to ensure a safe speed of 30 kmph at a distance of 100m from the danger signal.
 

By taking into account the train and track parameters, the system generates the permitted safe speed of the train. When the actual speed exceeds the permitted speed, the system alerts the driver by means of an audio visual alarm, and if the train continues to run at speeds exceeding 5 kmph over permitted speed and the driver fails to respond by reducing speed, the on board computer will actuate the service brake and achieve the speed control. However, if the actual speed exceeds the permitted speed by 10 kmph, emergency brakes will be applied and the train will be brought to a stop. Therefore, this is a system which controls the movement of the train when the signal is at danger.

The project was jointly executed by the Signal & Telecommunication as well as the Electrical departments of Southern Railway. Six officers and two supervisors were trained abroad in the installation, operation and maintenance of this system. Extensive trials were carried out by the Railway to adapt this system to Indian conditions on our EMUs. During the course of the project implementation, the trials and studies threw up a large number of issues which necessitated changes in the track side parameters and fitting of extra Balises.

Once the house trials were satisfactorily concluded, the Research Designs and Standards Organisation (RDSO) did a detailed study on the system and conducted further trials to give clearance to the brake and train interface. Four EMU rakes were initially equipped with this system at the time of inauguration following which another 16 rakes were equipped with the system. In a few months time, all 41 rakes which are used on the Gummidipundi section will be equipped with this system.