OLD London Underground trains being lined-up to replace the unpopular Pacers will be comfortable for passengers and cheap for operators, says the company behind the plan.

Union leaders have described the proposal to reuse tube trains as "piling lash-up onto lash-up and making a nonsense of the Government's pledge to create a Northern Powerhouse".

However, Vivarail, which this week released more details of its D-Trains, says it is creating one of the UK’s most technologically advanced trains.

The D-Train design uses the bodyshells, bogies and motors from surplus London Underground District Line trains.

Vivarail says the tube train bodyshells are made from corrosion-free aluminium, and will be re-engineered to give additional collision protection.

The company adds that the bogies, which are designed for lower-quality track, are barely ten years old.

According to the brochure, the existing electric motors will be powered by new underfloor-mounted low-emission diesel engines, equipped with the latest stop-start technology.

The trains will have a high power to rate ration, giving them good acceleration, it is claimed.

"The result is a train that is cost-effective to procure and operate, and smooth and comfortable to ride in," the brochure adds.

The Prime Minister has pledged that the Pacers will be scrapped, however a national shortage of diesel trains and uncertainty over plans to electrify more routes in the north, has prompted Vivarail to put the D-Train forward as the ideal solution.

Adrian Shooter, chief executive of Vivarail, said the UK-designed and built D-Trains provided an answer that only a pedant could refute.

The former chairman of Chiltern Railways added: “As a passenger I've suffered uncomfortable journeys on old trains, which are equally uncomfortable for staff to work on.

"Indeed it was one of the factors that led me to create the D-Train. I knew we had to keep it simple to make it viable, which is why recycling the existing shells works so well. By doing that we’ve been able to concentrate our efforts on the important bits - the engines, generators, computer systems and so forth – all of which have been designed and made to the highest specifications.

"It also means we’ve created a truly green machine. There is no other train like it available – and it’s made right here in Britain.”

The company says the D-Train prototype will be ready for train operators to view in early summer and will be ready to use by the end of 2015.

The Northern Echo has launched the Right Lines campaign to call for a better rail service for the region.