London Tube trains sent on rush hour collision course
A Tube train was sent into the path of another train during Wednesday morning's rush hour, it has emerged.
The driver of the Hammersmith and City Line train realised it had been wrongly switched to an eastbound track shortly after leaving Plaistow station.
Transport for London (TfL) said the train was stopped immediately and the nearest eastbound train was held at a red light almost 1km away at West Ham.
The Rail Accident Investigation Branch has been informed of the incident.
The Office of Rail Regulation has also been notified.
Last month an out-of-control engineering train, without a driver, went through six stops on the Northern Line before coming to a stop.
In the latest incident, a westbound train was turned around in sidings at Plaistow, east London, and incorrectly routed on to the eastbound tracks at 0818 BST.
After picking up three passengers at Plaistow station it was given a green light and pulled away from the platform.
It was only then that the driver realised the mistake. She stopped the train and raised the alarm.
The train was then reversed into the station so the passengers could get off.
Services on the District and the Hammersmith and City lines were partially suspended for about six hours to allow investigations to take place.
Initial investigations are understood to have identified a fault with signalling equipment at Plaistow station.
A TfL statement said: "The driver, following London Underground's stringent safety procedures, stopped the train immediately, and our signalling system prevented any eastbound trains from moving towards the stationary train.
"The nearest eastbound train was stationary at red signals almost 1km away at West Ham."
A London Underground worker who contacted the BBC but asked to remain anonymous said: "It is the most serious incident I have seen or had to deal with.
"Safety could be jeopardised by reducing jobs. It easily could get worse.
"Colleagues are shocked and amazed that such a thing could happen. People's lives could have been at risk."
TfL have previously denied that safety would be compromised by planned cuts.
A spokesman for the Rail, Maritime and Transport (RMT) union said: "Our health and safety representatives are fully involved in the investigation into this incident and we are awaiting the outcome of the investigation process."
TfL also confirmed that there was a derailment at Highgate Depot on Wednesday.
In a statement it said: "A train, which was not in passenger service, and was in a depot area, had a minor derailment at Highgate depot.
"This was not in an area used by passengers, and has not had any affect on services."
It went on: "There were no injuries. London Underground is investigating the cause of this incident, but believes it was a case of human error and was not a signalling or technical issue."