Tamil Nadu train crash: Outdated signaling system affects safety of Indian Railways | Travel

Although accidents continue to occur due to the decades-old signaling system, the Indian Railways does not seem to have learned its lesson yet. About a year and four months after the Balasore train disaster in Odisha, another accident occurred at Kavaraipettai near Chennai that left the country in turmoil. This latest incident, like the previous one, was due to disruptions in the signaling system. A total of 296 people were killed in the Balasore accident in June 2023 when the Coromandel Express collided with a freight train and the Howrah-Bengaluru Express. Many people also lost their lives when the Kanchenjunga Express derailed at Singur in Bengal, also due to signal failure. Trains often narrowly escape disasters due to signal failures and broken signal cables.

Electrification, signals and track infrastructure are crucial for train travel. While electrification and track modernization have made significant progress, the signaling system remains outdated. Although plans have been proposed to reform automatic signaling on subway system routes, these have not progressed far. Let’s explore how the legacy railway signaling system works and its various features.

How railway signals work
Trains across the country are instructed to follow specific tracks, with signals and tracks being prepared simultaneously. A railroad track is connected to another track via movable pieces of rail called switches, which are controlled by a mechanism called a switch drive. These machines are typically located about a meter from the rail at the same level and are often seen near train stations. An electric motor inside the box moves the tongue rails to change the rail path. When the stationmaster selects a particular route at the control panel in his room, the switches move accordingly and signals are displayed. Technical systems such as switchboard signal boxes, route relay signal boxes and electronic signal boxes are used to determine routes.

Flags and torches
During train journeys, station masters, guards and train drivers often wave flags and torches. The red and green flags of the railway staff are important signals in train operations. Even if a green flag signals the train to proceed, it will not move if a red flag is raised by any railway staff. Flags are used daily, at night they are replaced by LED flashlights. Another important signal is the detonator, used by track crews, train drivers and guards.

Signals for departure and maneuvering
The signal that indicates the departure of a train from a station is called a starter. As soon as all the tracks converge on the main line, another signal is given, the so-called pre-start signal. At some larger stations there may be an additional start signal between these two. The last start signal seen is the last stop signal at that station. In addition to red, yellow and green signals, white signals can also be found on small posts inside train stations. These are shunting signals that are used exclusively for operations within the station area.

“Kavach” in the spotlight
Whenever a train accident occurs, media discussions emphasize the urgent need to introduce the Kavach system across the country’s railway network. Kavach is a safety system designed to prevent collisions between trains. It is an automatic train protection system with the aim of preventing such incidents. The system, introduced by Mamata Banerjee, the railway minister in Manmohan Singh’s cabinet in 2011-12, was later renamed Collision Avoidance System (Kavach) under the first Modi government in 2014.

In 2019, three companies received approval to build and install the system, which was successfully tested in 2022. If two trains approach on the same track and the train driver cannot control the speed, the Kavach system automatically activates the braking system within a minute at the specified distance. This is made possible by radio technology and GPS. A train approaching another on the same track automatically stops at a distance of 380 meters. However, because the government has failed to install the system on all railway lines, the potential benefits of Kavach have not been fully realized.

What Kavach does
The Kavach system closely monitors train movement and automatically sends notifications of appropriate emergency actions.