PICTURE: Gareth Hannam
ACCORDING to Hanson spokesman David Weeks, the cause of Monday's crash could have been brake failure, but this has not been substantiated.
He said that according to unconfirmed reports a full train left the Hanson quarry on its way to Westbury.
Meanwhile, shunter which was attached to 16 wagons broke free and began rolling downhill along the track.
At some point five wagons and the shunter decoupled and when they reached a sharp bend at Great Elm they derailed. The other 11 wagons continued until they collided with the back of the train travelling to Westbury.
Five men were involved in the accident, three of them employees of Hanson, who had loaded the runaway truck, which eventually ran into the back of another stone train travelling in the same direction, derailing it.
The other two worked for a company called EWS Train Operation Company, and drive trains for Mendip Rail.
Mr Weeks described the men involved as unhurt but shocked.
The Railway Accident Investigation Branch (RAIB) took control of the heavily-wooded site and were expected to remain there, carrying out an investigation of the locomotives and the track. The investigation is expected to continue until the end of the week.
Mr Weeks described the track as a very important artery between the Mendips and the companies' major markets in the South East.
He said: "The market is depressed in any event, so this really could not have happened at a worse time."
Once the independent RAIB completed its investigation, the difficult job of clearing the derailed trucks from the largely inaccessible track began and repairs to the track were made.