The 6.5-tonne chassis have been fitted with additional sets of rail wheels at the front and rear, which can be hydraulically raised for normal road operation or lowered to allow the vehicles to run on rails.
The 175bhp engined 4x4 Canter 6C18Ds have Double crew cabs and were supplied by South Wales Mercedes-Benz Dealer Euro Commercials. They were converted by rail industry specialist GOS Tool & Engineering, of Blaenavon, South Wales, which worked with Network Rail's design criteria, having first established that they were the best trucks for the project.
Six were fitted with dropside bodies and PM cranes used to lift sleepers, rails and bags of ballast, while the remaining 14 have box bodies housing welding equipment for rail repairs – and all are now undertaking maintenance duties.
"The Canter 4x4 is ideally suited to this conversion – it's a low ride system, which means the road wheels sit on the rails, and the double drive gives plenty of traction," explains Neil Gregory, GOS Tool & Engineering director.
"Also, although the truck has relatively compact dimensions, there's still plenty of space on its ladder chassis to accommodate all of the equipment and ancillaries."
Network Rail project manager Keith Ubah says that, in operation, technicians can now drive to level crossings, position their vehicles over the track and deploy the wheels. The trucks can travel along the line to work sites.
"Safety is one of our top priorities and these crane vehicles significantly reduce the amount of manual handling of heavy items that for our maintenance crews, making life easier and safer," comments Ubah.
"We'll also benefit from increased efficiencies and reduced operating costs as they are doing a job that was previously assigned to separate road and rail vehicles."
Network Rail previously relied on a combination of standard road-going trucks and specialised railway vehicles –typically hired in under contract – to carry out maintenance work on tracks.
"So there's [additional] scope for cost saving too," continues Ubah. "By deploying these Canters, we will be able to start reducing the use of rented rail-only vehicles.
"The cranes also perform a very useful role in transporting valuable scrap metal, such as old lengths of rail, to access points where it can be removed. The savings, and the extra income generated mean the Canters should prove beneficial very quickly indeed."
Meanwhile, Network Certification Body (NCB) lead assessment engineer Olufemi Okeya confirms that the new vehicles are bringing "very real benefits" to Network Rail operations.
"So far, NCB has certified that the six general purpose vehicles are compliant with the relevant engineering standards," he states.
"The certification process involved working closely with GOS to develop a novel rail guidance and wheel-load monitoring systems. The acceptance work included development and witness testing, and reviewing the design proposals before the final sign-off."