Standard operating procedure has for the first time replaced standard operating panic during an emergency in Metro.
Train services were stalled for around an hour and a “thorough check” was carried out along the entire 25km stretch after officials at Metro Bhavan felt the tremors on Wednesday afternoon.
Officials described the suspension in service from 2.40pm to 3.30pm as “standard operating procedure” invoked to avoid a disaster.
“As a precautionary measure all Metro trains were vacated at various stations and passengers were requested to leave the station premises immediately. Engineers were asked to rush to the stations and take stock of the situation,” said Pratyush Ghosh, the deputy general manger, Metro Railway.
Metro engineers, along with experts from the Geological Survey of India (GSI), surveyed tracks before the service was allowed to resume.
No commuter or employee could recount an earlier instance of the city’s fastest transit system being stopped because of tremors.
Metro general manager P.B. Murty said the authorities were only acting by the rulebook in suspending the service and conducting a “thorough” check. “I don’t know why the services had not been stalled during or after earlier quakes,” said Murty.
Calcutta has experienced two other quakes since Murty took over as the Metro boss in October 2010. On neither occasion was the standard operating procedure put into practice.
Eighteen trains were stopped on Wednesday and passengers were asked through the public address systems to evacuate.
The scan began once the commuters left. Engineers walked along the tracks to check the facilities and empty trains were made to run at a slow speed. “We were looking for a crack on the tunnel walls and the tracks, or any damage to the wires and gadgets,” said an official.
The underground stretch comprises “box tunnels”, each around 40 metres long. Two boxes are separated by a gap a few inches wide.
“There could have been water seepage, leading to dangerous consequences, had the gaps widened because of the quake. Also, the part of the tracks below which any gap could have widened would have been damaged had a train passed over them,” an official pointed out.
An official working for Metro for almost two decades said this was the first time he saw the authorities take a proper approach when faced with a potential emergency. “Panic or knee-jerk reaction had been the norm in such situations,” he said.
For a section of passengers, though, the sudden evacuation did trigger panic.
“RPF guards at Park Street station told me the services had been stalled because of an earthquake. Scores of people were rushing out, fear writ large on their faces,” said Debabrata Biswas, 40, who was headed for Sovabazar.
Metro engineers said both the underground and the elevated stretches were strong enough to withstand tremors like the one felt on Wednesday.
On the elevated stretch between Tollygunge and New Garia (Kavi Subhash) stations, the tracks are supported by girders held by pillars.
“The structures are constructed to transfer load from the upper to lower portions. However, in case of an earthquake, the load transfer process is reversed and there is an upward thrust that puts the structure under stress. This often leads to cracks and dislodging of a structure,” said an engineer.
The pillars and girders of Metro tracks have been built with extra iron rods to endure the stress, he pointed out.
“The box tunnel on the underground stretch is a rigid structure in which the beams, columns and slabs are not separated. The compact nature of the structure will ensure that during tremors such as the ones the city experienced today, there is hardly any chance of damage,” the engineer added.