The 530-mile route, earmarked for privatisation next year, is expected to be upgraded largely with private-sector money in return for a concession to operate services. Trains carrying two layers of passengers are one of several options put forward in a feasibility study being carried out by a group of consultants and Railtrack.
A key object of the upgrading plan is to slash journey times between city centres by installing modern power and signalling equipment along the route, which runs from Glasgow to London with connections to Manchester and Liverpool.
Another option under review is tilting trains, such as those in Spain and Sweden, that can travel along sharply curving tracks at high speed.
The line is one of the busiest in the UK, carrying 2,000 trains a day. But it was the first important route to be electrified and much of the infrastructure is 30 years old.
However, many bridges and tunnels along the route would have to be raised and widened to allow for double-decker trains, which could add about pounds 100m to the project. Nevertheless, the idea has strong backing from private groups including Eurotunnel as it would also enable a 'piggyback' version for freight to operate on the route.
Piggyback trains, used extensively on the Continent as well as through the Channel tunnel, allow road trailers to be loaded directly on to rail wagons, making it quicker to transfer freight between road and rail. An upgrade that overcame the height limitations would provide a seamless link for freight between northern Britain and the Continent.Reuse content