The Rail Accident Investigation Branch has released its report into the incident on the line between Chester and Crewe in the early hours of September 19 2018.
A road-rail ballast distributor travelling in reverse on the line collided with a small personnel carrying vehicle.
Two track workers who were in the rear of the personnel carrier were injured, one of them suffering life changing leg and back injuries.
Investigators found the adapted ballast track offered very limited visibility when driven in reverse.
Simon French, Chief Inspector of Rail Accidents said: “Driving a truck loaded with ten tonnes of stones backwards for several miles along the road is not something most people would contemplate doing.
“When that truck has been converted for use on the railway, the driver no longer has to worry about steering it – but being able to see where you are going is just as vital.
“This sad accident, in which a member of railway staff suffered life-changing injuries, has revealed some alarming weaknesses in the design of railway equipment and the railway’s working processes.
“The machine that ran into a stationary personnel carrier was a road lorry that had been converted so that it could be used on both road and rail.
“On the railway, turning round is not easy to do and so it would have to travel significant distances in reverse.
“However, the driver’s seating and controls had not been altered, so when the machine was going backwards, the driver had to turn round in their seat, to see where they were going.
“The load of ballast carried by the lorry obstructed any view directly along the track.
“The RAIB’s investigation found that there had been inadequate consideration of the practical aspects of using such a machine on the railway.
“To comply with the rules, the machine would have to travel at walking pace, accompanied by someone walking alongside the track (usually in the dark), who would be at risk from all the tripping and slipping hazards of the modern lineside.
“This could mean taking hours to reach the site of work, wasting much of the time available for track maintenance at night. In this case, the crew ran backwards at an average speed of between 11 and 15 miles an hour, in the belief that there was nothing in the way.
“The RAIB is recommending that the industry takes effective action to ensure that its road-rail vehicles can be driven safely to and from the site of work, now and in the future.”