An undetected fault in the wiring in the location box near Bahanaga Bazaar Railway Station that had not been noticed by Signal and Telecom (S&T) staff in the past five years led to the deadly triple train collision in Odisha. Installed at a distance of two to five kilometres usually, a location box houses cables which control signalling functions, including points, signals and track circuits.
A Commission of Rail Safety (CRS) report accessed by The Hindu pins the fault on the S&T Department, which was conducting the repair work on the day of the accident, June 2. Railway officials who are studying the collision said that the accident could have been averted if due procedures had been followed by running checks on the circuit which sets points on rail tracks, connecting the location box with the relay or control room.
They said that the entire cascade of events, which dates back to lapses being committed by S&T staff since 2018, came to light and attention after it led to a major accident, which is a colossal failure of safety.
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Wrong labelling
On studying notes logged in the data logger device from 3 p.m. to 11.58 p.m. on June 2, the CRS reconstructed the flow of events leading to the accident and after.
Only at nearly 11.30 p.m., four hours after the accident took place, Senior Section Engineer (Signal Incharge) A.K. Mahanta, who was at the accident site, came to know from the test room that the indication of the point was still showing normal, even when the point machines at site were damaged. This piqued his curiosity and he went to check if there was any wiring mistake at Level Crossing Gate 94, where maintenance work for the Electric Lifting Barrier (ELB) was undertaken between 4.20 p.m. to 4.50 p.m. earlier on the ill-fated day of the accident.
It was revealed that in circuit diagrams, which were approved in January 2015, terminals F23 and F24 were assigned as spare terminals. Circuit diagrams need to prominently display the reasoning for the connections of cables and are pasted alongside the cables.
While they were labelled on paper as “spare terminals”, in actuality, the S&T staff, while ‘meggering’ (testing if the circuit is running well) of 30 core cables between central relay or control room, had shifted the 17NWKR circuit, which earlier used to work on terminals F13 to F23 and from F14 to F24. The 17NWKR circuit essentially fixes the point which the train is supposed to take for the mainline.
“The first fault of the S&T staff was that while they shifted the circuit, they did not change the labelling on the circuit diagram. This was very dangerous,” Railways officials told The Hindu.
They further said that a labelling mistake that had gone unnoticed since 2018 cost the Railways dear on June 2. While the wiring work was being carried out on the control operation of the ELB, the S&T staff thought of the F23 and F24 terminals as “spare”, and rewired the new ELB connection to the those terminals.
“The S&T staff realised later that they had disconnected the feed coming from the crossover 17A/B (the point at which accident happened) to 17 NWKR circuit. As a result, the indication feed (of the green signal) was disassociated from the status of the point at site,” officials explained.
Routine tests missed
The S&T staff has testified in the CRS report that they had no knowledge the the 17NWKR circuit had been shifted to the “spare” F23 and F24 terminals as the wires were drawn from the rear of the rack and were not visible on the front. But officials argued that the fault went unnoticed as the S&T staff was adopting “shortcuts” and not running routine checks (effectively every six months) on circuits.
“One needs to ensure, for instance, that the switch meant for a fan connects to the terminal meant for the fan on a switchboard and that for light connects accordingly — these cannot be swapped, which is what happened in this case,” they said.
Officials said that routine “cable continuity tests” need to be conducted to check that all circuits were properly assigned to the functions that they had been “labelled” to perform. “This does not seem to be done,” they said.
The result was lethal. At 6.14 p.m., a few minutes before the collision, the point had been set to reverse for the reception of UP goods train on the UP loop line. Later, another goods train was received on the UP loop line.
Later, a command was given from the control room to again set point from reverse to normal to receive the Shalimar-Coromandel Express, and a “normal” indication appeared on the panel of the control room. However, due to the fact that cables had been disconnected by the S&T staff, the actual point remained in reverse, pointing towards the loop line.
“Physical state of the point was reverse, but status in relay room and on panel was normal — this is very dangerous. The physical state of the cross over (point) was out of correspondence (delinked) with its indication relay, and was being fed through some other circuit/source,” the CRS report points out.
“There was no way to then know that the physical point had not been changed, as it was ‘assumed’ to have changed. But the wiring had been tampered with. Before giving an all clear, a cable continuity test to check whether the circuit was working fine, or if the labelling was wrong, had not been done, which is a great failure on the part of the S&T staff,” the officials said.
“These cable continuity checks are sometimes skipped due to shortage of time on high traffic dense rail routes. Even checks every six months may not be carried out regularly to see if all circuits are working fine,” they said.
Previous ELB work
The first level of failure was in the wrong labelling of circuits and the second was in failing to check if the circuits worked normally by conducting cable continuity or the so-called “buzzer” tests, which send signals from one point to another and wait to receive the signal back to see if the loop was complete and worked in the way it was intended.
The CRS report also points out that the S&T staff had not acquired an approved circuit diagram for the execution of ELB replacement work at LC-94.
“Railways had planned to reuse the pre-wired location box of ELB at LC-79 at Balasore station (which was closed sometime ago) for the ELB replacement work of LC-94. So wiring diagrams of LC-79 were supplied to the S&T staff, but wiring diagrams of LC-79 could not be implemented in toto, and a lot of alterations had to be done to suit the site conditions, which should not have been left to the discretion of the field-supervisors,” the report points out.
It further says that if the wiring diagram of LC-79 had been emulated for the new work, there would have been no need to alter the circuits at “spare” terminals F23 and F24, which could have prevented the mistake.
The CRS has now also recommended that a separate team be deployed for checking and testing of all modified circuits at railway stations for averting any past mistake that could result in accidents.
