A ScotRail train carrying passengers has been hit by the door of another train that was swinging open as they passed each other in the middle of Edinburgh.
The incident near Waverley station in Edinburgh saw the train from Dunblane hit, but no one was injured.
Its startled driver leapt from her seat as it happened.
The collision was caused by a door on one of ScotRail’s 40-year-old intercity trains, which was being driven empty to a depot at Haymarket.
ScotRail was unable to explain why it had happened.
However, it is seen as more likely to have been a mechanical fault than human error.
ScotRail said “slight” damage was caused to the door and the other train was undamaged.
The train involved is thought to have operated a passenger service from Aberdeen which had arrived at Waverley 15 minutes earlier.
ScotRail said the driver had checked the doors on the platform side were all closed before leaving, but the open door is believed to have been on the other side of the train.
ScotRail said a panel in the driver’s cab had indicated all the doors were closed.
The collision happened around 10pm on Saturday between Haymarket and Waverley, with the 20:58 service from Dunblane being hit.
An industry source said: “The driver of an approaching service from Dunblane had to jump from her driving seat as the door struck her train.”
The train which caused the incident was one of ScotRail’s unrefurbished, or “classic” former High Speed Trains (HST), which still have old-fashioned “slam doors” which open outwards.
They are operated by turning the outside handle, but are centrally locked while the train is in motion.
The source said: “There are two directions the doors can open - facing back and facing forward.
“When that door hits something, it’s in the wrong direction to knock itself closed, and that’s what this was.”
The operator was forced to press the trains into service last year because of delays with their upgrading, including new electrically-operated doors that open sideways, like the rest of the company’s fleet.
The train which was hit was one of ScotRail’s newest, a Hitachi electric class 385.
A ScotRail spokesperson said: “On Saturday night (11 May), while on its way to Haymarket depot with no customers on board, a train door opened and was hit at low speed by a passing train, causing minor damage.
“A Class 385 travelling to Edinburgh Waverley clipped an open door of an HST which was leaving for Haymarket depot.
“It is true the 385 driver left seat as a precaution.”
A spokesperson for the UK Department for Transport’s Rail Accident Investigation Branch (RAIB) said: “The RAIB was notified of the incident.
“From the information we received, it was unlikely that an investigation would lead to safety recommendations, so in this case we are not taking further action.”