275 people were killed and around 1,000 injured in Odisha's three-train accident.
The three-train tragedy in Odisha's Balasore, which left 275 dead and around 1,000 injured, will be investigated by the CBI. The move is significant as sources say only a detailed probe by a top agency can establish criminal tampering, if any, with the point machine or the electronic interlocking system, or if the train changed tracks due to reconfiguration or a signaling error.
The CBI inquiry will answer all queries regarding the accident -- the worst in the country in the last two decades.
Along with the CBI inquiry, the probe by the Commissioner, Railway Safety, will also continue and a report is expected in two weeks.
On Sunday, Railway Minister Ashwini Vaishnaw told national broadcaster Doordarshan that the "root cause" of the accident and the people responsible for it have been identified. Prime Minister Narendra Modi said a day earlier that strictest action will be taken against those found guilty.
Mr Vaishnaw said a change in the configuration of the track may be the cause and that "whoever has done this will be not spared". Railway experts said the electric point machine is the most important device for railway signaling, necessary for the locking of point switches, and critical for the safety of the trains.
SK Sinha, an Indian Institute of Science (Bangalore) alum who founded L2M Rail - a startup committed to boosting safety and sustainability of the Railway Industry - told NDTV that electronic interlocking permits setting up of a route for a train by the station in-charge.
"...Once the route is set and locked, the route cannot be changed until the train completes its movement over the locked route. Signals are green on the routes set and locked for the driver to know that this route is reserved for him and he can go ahead. All events are recorded and available for post-event analysis, and I am sure officials would be studying the data logs to understand what went wrong. The electronic interlocking systems used in Indian Railways are quite robust and conform to the highest level of safety standards and it is unlikely that it would have failed on its own..," Mr Sinha said.
He added that the most common factor in train derailments is track failure. "Extreme temperatures may cause the track to bend or crack. Weld failures also happen. However, deliberate damage to the tracks caused by anti-social elements has been a major issue for Railways. Tracks are inspected twice a day, manually. However, it is possible and desirable to develop systems to monitor tracks 24/7 and report any abnormalities in real-time," he said.
Nalinaksh S Vyas, Professor, Department of Mechanical Engineering at IIT- Kanpur suspects a systems failure.
Mr Vyas, who has headed the Technology Mission for Indian Railways (TMIR), said, "It looks like there was some lack of synchronisation between the electronic and mechanical systems. The way the point works is that it needs to change its position from the main line to loop line or vice versa, and the signaling should happen too simultaneously.
"So there is a mechanical action, which is basically the shifting of the point from inclined to straight, and there the rotating of the motor to go from loop to main that goes along with the electronic action. It is possible that the signal was showing green, but the point was still inclined or partially inclined. It is rare and the Railway Minister is right in identifying this issue, and getting this probed," he said.
Mr Vyas said the preliminary findings indicated the investigation was in the right direction. The Commissioner of Railway Safety, South Eastern Railway, is already carrying out a probe in the matter.
The probe will also examine the failure of the track management system, signaling failures and other possible angles such as human error, weather issues, communication failure or otherwise, sources said.
Railway Board Member (Operations and Business Development) Jaya Verma Sinha on Sunday told the media that the people responsible had been identified and that there was no defect in the logic of the signal.
Ms Sinha had said the track management system was supposed to be tamper-proof, error-proof and fail-safe because even if it fails, the train would be stopped. "However, as it is being suspected, there was some kind of interference with the signaling system," she said. When asked if the railways suspected foul play, Ms Sinha said nothing was ruled out.
Sensorization of tracks, addressing track failures important
Prof Vyas said the way forward was to ensure complete sensorisation of at least 40,000-Km long tracks of the Railways so that there is no break in seamless communication, and the installation of anti-collision systems such as Kavach on all railway lines. "It is good that all angles are being probed. The tracks should have had the information that there was a stationary goods train in the loop line. It is important that the benchmarking, certification, adoption and facilitation of such technology on whom millions of lives are dependent are done at the top level, and not left to a few individuals or organisations, and such decisions are taken faster."
Prof Sinha said while Kavach, an anti-collision system, is a good move to prevent disasters due to human error, it too has limitations and cannot prevent accidents due to system failures on the ground.
"However, overlay systems can be developed to use the Kavach platform and prevent accidents due to other scenarios," he added.
Former Railways engineer and retired IRSE official Alok Kumar Verma said, "Basic things like proper inspections and maintenance and meticulous train operations are crucial."
"All concerned field officials should get adequate traffic blocks and other backup support like the movement of material and manpower to sites to carry out inspections, fault diagnosis and repairs. Station Masters, train pilots, guards, trackmen, signalmen etc should get adequate rest," he said, adding that the root cause of the problems of inadequate maintenance was the severe congestion on key routes.
"This problem has a cascading effect of trains running late, chaos in train operations etc. Updating technical skills and provision of good tools are also important," he said.
"The present signaling system tells the driver whether he can go ahead or not. No information on the conditions ahead are available to him. IISc, through one of its start-ups (L2mRail) has developed and patented 'Cyber Signalling' which provides real-time information to the train driver about his surroundings and the route ahead. Cyber Signaling has been deployed at JSW Steel plant in Toranagallu, Ballari, Karnataka. This concept can be developed further to adapt it for main line operations."