- Chennai
- Election-2026Election-2026
- Tamil Nadu
- National
- World
- Cinema
- Business
- Sports
- Lifestyle
- Technology
- Videos
- Explainers
CHENNAI: Over the past year, Tamil Nadu’s railway network has taken a major step towards enhancing passenger safety with the launch of the ‘Kavach’, an automatic train protection system.
Nearly a year ago, Tamil Nadu began installing a one-of-a-kind sensor controlled train protection system called Kavach on a few of its frequently used rail routes. Cut to the present, the 160-km stretch between Chennai and Renigunta is fully operational while work is in progress on the Chennai–Vijayawada and Chennai–Coimbatore stretches.
According to experts, for 2 million passengers who are patrons of the Southern Railway on a daily basis, the new system promises a drastic reduction in the risk of collisions. However, not many understand how the system works to ensure safe passage for trains.
The word ‘Kavach’ which literally translates to protection is an automatic train protection (ATP) system developed by the Research Designs and Standards Organisation (RDSO) in collaboration with the Indian railway industry. It is designed to enhance safety by performing two important functions. It prevents a train from jumping a red signal, a failure railway engineers refer to as ‘Signal Passed At Danger’(SPAD) and it ensures that the train never exceeds the speed limit on a given stretch of track. Experts point out that a train moving at 100 kmph speed takes at least a kilometre to come to a halt which does not give the loco pilot the luxury of responding at the last moment. While fatigue, fog or a momentary distraction can turn a missed signal into a fatal collision, Kavach is designed to catch that lapse before it becomes irreversible.
However, Kavach uses a more old school but reliable method in which RFID (Radio Frequency Identification) tags are fixed on every kilometre of the track. Each tag carries the exact location and also the distance to the nearest station. Owing to this, two tags placed a few metres apart allow the system to determine the direction in which the train is travelling.
Similarly, the trains are fitted with an RFID reader and speed sensors on its axles. By reading a tag and continuously measuring the wheel rotation, the computer onboard calculates the train’s exact position until it encounters the next tag. Experts note that this method keeps errors considerably low and aids the loco pilots to be well informed of the various signals on the route along with the speed restrictions.
However, knowing the exact location of the train solves only half the problem as Kavach also needs to know what is displayed at the next signal junction and details of the speed limits that are ahead. All this information comes from what engineers call the station kavach which is a small computer installed at stations and trackside locations.
The station kavach collects data from signal poles, track switches and a central server at the divisional headquarters that issues temporary speed restrictions. It then transmits this data wirelessly to the trains where inside his cabin, the loco pilot can see information about the next signal, current speed and any upcoming restrictions on a small display.
If the pilot does not slow down in time for a red signal, Kavach would first issue a warning followed by an instruction and finally, at the very last moment, it would automatically engage the brakes. While the pilot remains in control of the train, Kavach is designed as an assistant that stays alert to avoid accidents that can happen due to manmade errors.
· On-board loco devices that can continuously monitor train speed and movement
· RFID tags installed on tracks that help monitor movement and communicate information to trains
· Stationary towers and locomotive-mounted radios for real-time data exchange
· Automatic braking if speed limits are exceeded or a signal is passed at danger
As of last month, Kavach has been deployed over 1500 kilometres across the country, mainly in the South Central Railway route and and currently in Southern Railway routes. In Tamil Nadu the routes that have Kavach are as follows:
· Chennai–Renigunta (160 km) : fully operational
· Chennai–Vijayawada (430 km) : pilot completed and rollout process in progress
According to Southern Railway the following sections will be fitted with the safety system soon:
1. Chennai–Vijayawada to be complete by December 2026
2. Chennai–Coimbatore to be completed by mid-2027
3. Coimbatore–Mettupalayam to be completed by 2027
4. Madurai–Kanyakumari to be completed by 2028
5. Tuticorin–Tirunelveli–Madurai to be completed by 2028
Tamil Nadu has over 3800 route kilometres of railway track and once Kavach is fully deployed, it is expected to considerably eliminate the risk of rear-end and head-on collisions. Most importantly, the fatigue and exhaustion experienced by the loco pilot will come down considerably.
Since Kavach allows signals to be placed as close as one kilometre apart, more trains can run on the same track without compromising safety which will result in the increase in average speed of the locomotives. Apart from this, freight trains on industrial corridors like Chennai–Tuticorin can ply more efficiently once they get the automated safety system.