On the evening of February 8, the Sampark Kranti Express had crossed the Hosadurga Road station in Mysore division when the loco-pilot realised that something was very wrong.

He was heading for a collision.

The train had been diverted to a line where a goods train was already standing. Fortunately, the Sampark Kranti Express was not travelling at a high speed. The pilot applied the brakes and averted an accident.

According to Hari Shankar Verma, who was at the time the principal chief operations manager of South Western Railway, this was a sign of a “serious flaw” in the system.

The next day, he shot off a letter to the general manager, deputy general manager and divisional railway manager of the South Western Railway, flagging his grave concerns.

Four months later, with a triple train collision in Balasore, Odisha, on June 2 claiming 278 lives, the focus is back on Verma’s warning.

In the train crash in Balasore, too, the accident occurred because the Howrah-Chennai Coromandel Express was mistakenly diverted to a line near the Bahanaga Bazar railway station where a goods train was parked – when the signalling system ought to have guided it to a line cleared of all train traffic.

The Coromandel Express rammed into the goods train and derailed. As its coaches scattered, they hit the tail-end of the Yesvantpur-Howrah Express, which was hurtling past on the adjoining track, and pushed its coaches off the track. The result was the most devastating rail accident since 2016, with 278 dead and 1,100 injured.

On June 4, railway minister Ashwini Vaishnaw told the media that a “change” in the electronic signalling system had led to the accident. While an investigation by railway authorities is still on, the Central Bureau of Investigation has also been brought in to probe the reasons for the accident.

What is uncontested is this: The Indian railways’ “fail-safe” electronic interlocking signalling system had failed. Scroll spoke to railway experts, station managers, and those involved in the signalling system to understand why such failures occur and how rail staff respond to them.

Rescue operations underway in Balasore on June 3. Credit: PTI.

The ‘fail-safe’ signalling system

In any mass-transit system, signalling is an important part of safety and punctuality.

In Indian rail system, it has evolved from manual signalling, by railway guards using flags and levers, to the current electronic and software-based interlocking system.

The electronic interlocking system is at the heart of the signalling system of the Indian railways. It has been expanded over the last 10 years across nearly 68,000 km of track.

There are three elements to this system – track sensors, the point and the signal.

“The sensors on the track help assess whether the railway line, all the way until the next signal, is clear of other trains,” said Subodh Jain, a former member engineering of the railway board.

Once the track sensors relay this information to the system, a point is set and locked.

Points are moveable rail tracks that direct a train towards the right track, especially when two lines are forking.

Depending on whether the line ahead is clear or not, the point guides a train to continue on the same track or diverts it to an adjoining track.

Once the point is set, it remains immovable until the train passes through. The loco-pilot can only increase or decrease the speed of the train, or apply the brakes.

“If the train is set to continue on the main line and the track is clear, a green signal is given to the train,” Jain said.

If the train has to go on the loop line, which are shorter tracks parallel to the main line, leading to a platform or serving as a diversion from the main line, then the signal is yellow. “The yellow signal means the train has to slow down as the maximum speed on a loop line is 30 kmph,” Jain said.

If the main line has a barrier, then a red signal lights up.

This is considered a “fail-safe” system, which is to say that it is programmed to stop operations at the hint of any error. “If the system malfunctions at any point, the signal automatically turns red and the train has to stop,” said a senior official from Centre for Advanced Maintenance Technology, or Camtech, a department under the railways that handles maintenance of technology.

Like any other equipment, the interlocking system can suffer routine failures. It may also be needed to be temporarily disabled when routine maintenance work is carried out on a track.

On paper, the electronic interlocking signalling system is supposed to work with minimal human interference. It is faster and less time-consuming.

But experts and officials Scroll spoke to said there have been “several instances” when it has been manually meddled with by the railway staff – despite it being expressly forbidden to do so. In many cases, the experts said, railway staff choose to cut corners because they are pressed for time and working under high pressure on highly congested train routes.

The warning from Hosadurga

Just before the Sampark Kranti Express passed Hosadurga station on February 8, the interlocking signalling system had developed an error in its axle counter, a device that detects the passing of trains on a track.

An Indian Railways internal note in 2011 had observed that such failures are frequent and lead to delays in trains.

In such cases, when the electronic interlocking signalling system malfunctions, the protocol is clear.

First, the station master must be informed of the error. Not only that, before allowing a train to proceed, the station master must now manually check the track and lock the points.

Once that is done, the train’s loco-pilot is handed a “paper line clear ticket” – an all-clear issued on paper.

The same process must also be followed when the electronic interlocking system has to be temporarily halted to carry out maintenance work on tracks.

On February 8, around 5.25 pm, the Sampark Kranti Express was allowed to continue on the up-line.

But, as the train’s loco pilot soon realised, because of an error in the way the point was locked, the track had been wrongly diverted to the down-line where the goods train was already stationed. A disaster was prevented because the loco-pilot was alert enough to catch the error and apply brakes.

In the letter flagging this incident to the rail authorities, Verma had raised concerns over actions taken by the signal technician and signal maintenance staff.

Verma told Scroll that an inquiry had found that a staffer from the signal and telecom department had manually tinkered with the wiring of the signalling system – which they were forbidden to do – resulting in the point being locked towards the wrong line. “The concerned employee admitted [his error] and was suspended,” Verma said.

Jain, former member of the railway board, said that Verma’s letter was a warning that “electronic interlocking can be meddled with and [that] is a serious issue”.

Verma said he is not sure if a similar incident occurred in Balasore. “That the investigation will find. I can’t comment,” he said.

Sudhanshu Mani, a retired general manager in the Indian Railways, said, “If this practice is prevalent, then it is a more serious concern and the top management has to do something about it.”

What might have happened in Balasore

More than 150 trains pass through Bahanaga Bazar station over a week. In each passage, the interlocking system comes into play. According to Yogesh Baweja, director general, public relations in railways, this is a highly congested route, with trains passing by frequently.

The Coromandel Express left Balasore railway station at 6.40 pm and neared Bahanaga Bazar railway station by 6.52 pm. At 6.55 pm, the Yesvantpur-Howrah Express approached Bahanaga Bazar station from the opposite direction. Both trains were supposed to pass by, not stop.

The Yesvantpur train received a green signal to continue on the down-line. From the opposite direction, the Coromandel too received a green signal to continue on the up-line.

But, unknown to the loco-pilot, the point had been locked to the loop line, where a freight train was already stationed.

The inevitable happened – at 6.55 pm, the Coromandel Express, travelling at a speed of 128 kmph, had a head-on collision with the goods train.

Since it was filled with iron, the goods train did not derail.

Rescue workers gather around damaged carriages at the accident site in Odisha. Credit: Dibyangshu Sarkar/AFP.

The Coromandel Express bore the brunt of the impact. Its engine climbed atop the goods train.

At such a high speed, Jain said, it would be impossible to apply brakes even if the loco-pilot had seen the goods train.

The Yesvantpur Express had almost passed by, except its last two coaches, which were hit by the toppled coaches of the Coromandel Express and overturned.

The Camtech official said there are two possibilities for the fatal error. “This is a software-based system. Either the system malfunctioned or someone manipulated the signalling,” they said.

The official said that the accident implies that the required protocol was not followed. “Whether there was a malfunction in the system, or some routine maintenance work undertaken at the time, or some work was going on on the tracks, has to be investigated.”

Baweja, director general, public relations in railways, told Scroll “no work was undertaken” on the tracks at that time.

Media reports have suggested that a snag in the level crossing had forced the signals to go red. But, in order to allow a quick passage to the Coromandel Express, the ground staff may have manually overridden it to turn the signal green which led to the accident. It is unclear if the station master was informed.

Where does the buck stop?

Railway officials spoke of the many conditions under which ground staff often resorted to cutting corners.

“Suppose some maintenance work needs to be done on a track or block, the procedure is to seek permission from the station master, asking for the electronic system to be disabled as well as to disallow other trains on that track,” a Mumbai suburban station manager said. “The set procedure is clear. But sometimes the procedure is bypassed and the ground staff takes a shortcut.”

Opposition parties have called for the resignation of railway minister Ashwini Vaishnaw after the accident. Credit: PTI.

Another Mumbai-based station master, who asked not to be named, said that when the interlocking system malfunctions or if maintenance work has to be done on a train, the entire protocol to allow a train to pass can take time.

“An entry is made in the register to make a record, then a written memo is issued by the station master to manually give permission to the train to pass,” he said. “Till then, the train will wait and traffic congestion can build up.”

Mani, the retired general manager, said the manual overriding of the electronic system means the staff “either do so under pressure of work or they use it as a shortcut”.

“If they do it under pressure, then the buck cannot stop at the signal maintainer and the station master. It goes higher up,” Mani said.

“Safety has to be given priority over punctuality,” he said, adding that if protocol had been followed, then “the trains would have been delayed for some more minutes, that’s all.”

Another retired railway official said station masters work under tremendous pressure to ensure punctuality of trains while undertaking routine maintenance work on tracks. If a block or track is closed for work, trains can be delayed. Skipping procedures to save time is a routine practice, the retired official said.

Instead of issuing a memo, an employee from the signal and telecom department changes the wiring in the junction box to manually operate the system, the official said.

Indian railways, say experts, is grappling with the challenge of congested train routes. Credit: AFP.

A systemic problem

It is a view echoed by other experts.

“Recently, several railway accidents have been due to human error. But human error is an indicator of a larger malaise in the system,” said Sarabjit Singh, former general manager, Indian Railways.

He added that signal maintenance staff work under tremendous pressure and have very little time to finish work. “They have to do their job plus ensure punctuality of trains. That is when they look to cut corners,” he said.

According to Singh, while the railways has added new trains, capacity has not kept up.

“Over the last few years, new trains and stations have been added but equivalent investment in capacity has lagged behind,” he said.

In an interview with Scroll, retired Indian Railways engineer Alok Kumar Verma had also pointed out that the congestion on train routes was at worrying levels. “Ten thousand kilometres of Indian railway routes are running at 25% above capacity,” he said. “To run with required safety, with adequate time for maintenance and to ensure punctuality, you should not run above 90% capacity. The desirable figure is 75% capacity. That’s the level of congestion in the railways.”

Singh said the only solution is to ease the pressure, reduce the number of trains, and increase investment until the infrastructure can support more trains.