An investigation into India's deadliest rail crash in more than two decades is underway, with preliminary findings pointing at a signal failure as the likely cause of the collision that led to the death of 275 people.
THE ROUTE
The collision of three trains took place at Bahanaga Bazar Railway Station in Balasore district, in the eastern state of Odisha.
The Bahanaga station has electrified double tracks and adjacent loops which are side tracks used to park trains.
Indian Railways' east to south route is very busy for both passengers and freight.
WHAT TRAINS WERE INVOLVED?
* Coromandel Express, which runs from Kolkata in the eastern state of West Bengal to Chennai in the south, was moving at a speed of 128 kilometre per hour.
* Howrah Superfast Express, which runs from the tech hub Bengaluru in southern India to Howrah in the east, was running at 126 kilometre per hour.
* Stationary freight train carrying iron ore.
WHAT CAUSED THE TRAIN CRASH?
Shortly after sunset, at about 6:55 pm IST on June 2, Coromandel Express and Howrah Superfast Express were moving on parallel tracks in opposite directions, with neither of them scheduled to stop at the station.
Meanwhile, the freight train was parked on the adjacent loop line.
A malfunction with the signal system is suspected to have led to the accident.
The driver of the Coromandel Express was routed to continue straight on the main line with a green signal, but the track diverted the train to the loop track.
The engine climbed on the last coach of the freight train and a handful of other coaches toppled. Most of the impact was felt by the Coromandel Express due to the freight train's heavy load of iron ore.
A couple of the coaches jumped the tracks and fell towards the right, hitting the last two coaches of the Howrah Express which had nearly crossed the site in the opposite direction.
At least 275 people were killed and around 1,200 were injured.
WHAT'S HAPPENING WITH THE INVESTIGATION?
Railways officials said that failure of the track management system was the main focus of investigations.
Railways officials and witnesses began submitting evidence to a two-day inquiry that opened on Monday in West Bengal state, after the Railway Board recommended that the federal Central Bureau of Investigation (CBI) take over the probe.
Railway police filed a case of criminal negligence, without identifying any suspects.
(Reporting by Tanvi Mehta; Editing by Simon Cameron-Moore)
