The incident happened in June 2018 when the road-rail machine was being placed on the tracks near Bradford Interchange station.

The machine operator and controller were able to run alongside and warn track maintenance staff to get out of the way.

The machine ran away because its rail wheels were, incorrectly, partially deployed and because the rail wheel braking system had not been correctly maintained.

The Rail Accident Investigation Branch is now calling on contractors to improve their competence management systems

Simon French, Chief Inspector of Rail Accidents said: “Getting road-rail plant safely on and off the track ought to be a straightforward business.

“Unfortunately, over the years RAIB has had to investigate too many incidents in which this operation has gone wrong, and the machine involved has run away downhill, often for quite long distances.

“Too often the people in charge have not known what to do to stop the runaway. In this case, the machine operator’s actions were not in line with what he had been trained to do, and no-one had checked on him.

“Of greater concern, however, is that the machine’s brakes did not hold it stationary on the 1 in 46 gradient.

“This was because they were badly maintained, a state of affairs that can be traced back to poor instructions and inadequate supervision of the plant hire company’s maintenance staff.

“The management of safety in the rail plant industry is something that RAIB has expressed concern about before.

“In the past, one of the important issues has been the competence of machine operators and maintainers. In this case, the problems were not only at the plant hire company.

“The project to convert many road-rail vehicles to direct rail wheel braking also lacked important elements of safety assurance, such as provision for proper information about the machines being converted, and adequate arrangements for training the people who would have to maintain the new braking systems.

“This incident provides an opportunity for the industry to learn major lessons from a relatively minor event.

“Our recommendations are directed to Network Rail and one other company, but I hope that people in all areas of the rail plant sector will take note of the learning points in this report, and make sure that their company safety management systems are comprehensive and fully implemented.”