Delhi Metro Rail Corporation on Wednesday said that the staff — who were in control of an empty Magenta Line train, that broke through a boundary wall at the Kalindi Kunj depot during a trial run on Tuesday afternoon — became overconfident and ticked a checklist without checking the train systems manually.

Delhi Metro has suspended four officials for the mishap, which included one deputy general manager who was the depot in-charge, one assistant manager under him responsible for depot activity, a junior engineer and an assistant section engineer who were involved in operating the train. The suspension is based on the probe by a team of three executive director rank officials.

The incident occurred at 3.40pm on Tuesday at the Kalindi Kunj Metro depot. The 12.64-km stretch is part of the 38.23-km Botanical Garden-Janakpuri West corridor under the Metro’s Phase III of the expansion plans.

The section that has nine stations: Botanical Garden, Okhla Bird Sanctuary, Kalindi Kunj, Jasola Vihar-Shaheen Bagh, Okhla Vihar, Jamia Millia Islamia, Sukhdev Vihar, Okhla NSIC and Kalkaji Mandir.

When asked whether this incident will dent the image of Delhi Metro, DMRC chief Mangu Singh told Hindustan Times, “All these things are temporary. This incident will be overshadowed by our good work.”

According to initial investigations, the train was to be taken to the washing area and the in-charge at that time took it without resetting the brakes. The incident took place when the train was being shifted from maintenance area to the washing area. The maintenance area does not have power and the train is pushed or pulled by a separate vehicle and for this the brakes have to be disabled.

“We have a system as per which the person in charge of a train in the maintenance depot hands over the train to another personnel to take it to the power area (washing area). Before handing over, he goes through a checklist and brake reset is a part of it. He also records it in the register,” Singh explained.

Singh said that in this case, the Metro personnel simply ticked the brakes reset box without actually checking it. “The next person who takes over is supposed to cross check each and every item. Then only he takes the train. This is a mistake on part of both of them. It appears like it was overconfidence because of which one fellow simply ticked the checklist and the other believed (him) and took the train away for washing,” Singh said.

The washing plant of the train is set on a gradient ramp. The person in-charge of the train tried to stop it on the ramp, but couldn’t do so as there was no brake. As a result, the train reversed down the slope and crashed into the wall.

The train was to be part of the Botanical Garden-Kalkaji Mandir section, which is to be inaugurated by Prime Minister Narendra Modi on December 25. Singh said that operation will not be affected since only one coach was damaged.

“If you send your car to a garage and something happens, will you call it a fault on the part of the car and say that the car is of no use now? This is not the same train which will run on main line,” Singh added.

Singh also said that wherever there is a manual system, they have to trust the person.

“Now after action is taken, people will be more careful and see that checks are done properly,” he added.