Merlin Entertainments, the company that owns Alton Towers, has revealed the cause of the Smiler rollercoaster crash earlier this year.  The collision, which saw four people seriously injured, was due to "human error" of the staff, according to a statement. The company said staff allowed a manual override of the safety system, which caused the occupied carriage to collide with a stationary carriage. A statement released by Merlin Entertainments reads: "The investigation concluded that the incident was the result of human error culminating in the manual override of the ride safety control system without the appropriate protocols being followed. "The investigation also identified areas where protocols and the training of employees should be improved. There were found to be no technical or mechanical problems with the ride itself. "We have taken full responsibility for the incident and continue to co-operate with the on-going Health and Safety Executive (HSE) investigation. "We are confident that lessons have been learned and that appropriate action has been taken to address all the issues raised by our investigation and we believe our core conclusions will be in line with the HSE findings." The crash resulted in two victims needed leg amputations and serious leg injuries for two others, with a total of sixteen injuries. The operator accepts "full responsibility" for the crash and it is expected that compensation payouts will exceed £1 million. The ride has remained closed since the incident and a Health and Safety Investigation is ongoing. The ride is expected to reopen next year.