Interviews with three railway officials, and press briefings by other officials, offered insight into the moments before the crash.

The Coromandel Express, had departed Kolkata with about 1,250 passengers and was passing the Bahanaga Bazar station in Balasore, traveling at a speed of about 80 miles an hour; it was not supposed to stop there. At the same time, the Yesvantpur-Howrah Superfast Express, with 1,039 passengers onboard, was exiting the station and heading in the opposite direction.

At 6:55 p.m., the Coromandel suddenly veered onto a looping track where a freight train carrying heavy iron ore was parked. As the first train smashed into the freight train, nearly 20 of the passenger cars derailed — some were flung into a farm on the other side and others struck the tail of the second passenger train.

Two senior railway officials, speaking to reporters in Delhi, said they had firmly established several factors: The Coromandel had received a green signal as it reached the Bahanaga Bazar station, the train was not speeding, and it had not crossed a red signal.

The tracks are managed by an “interlocking system,” they said, that determines what signal — green to pass, yellow to slow down, red to stop — would be given to a train. While interlocking systems can be managed manually or electrically, the officials had determined that the one at the station was electronic.