The government is investigating after a train hit equipment that had been left on the track.

At around 6.43am on April 25, the Wolverhampton to London Euston train crashed into a temporary road-rail vehicle access point near Kings Langley station.

The damaged train had to be held at Watford Junction and other services became congested because they had to use different lines to get around it.

A preliminary investigation by the Rail Accident Investigation Branch has been ongoing and more information has now been released.

“Rail ballast and debris resulting from this collision then struck a second train which was travelling in the opposite direction on an adjacent line,” it said.

Watford Observer: The location where the crash took place.The location where the crash took place. (Image: RAIB)

“Ballast also struck the platforms at Kings Langley station, which were at that time unoccupied.

"The temporary access point had been used during the previous night as part of rectification work to overhead line electrification equipment.

“No one was injured as a result of the collision and neither train derailed. The damage caused to both trains meant they were unable to continue in service.”

Based on the evidence which has been gathered so far, the agency has decided it will be publishing a safety digest with learning points to identify good practice.