It's more than 40 years since the Government closed a third of the country's railway network, transport experts believe reopening the disused lines could solve the current gridlock.

It's more than 40 years since the Government closed a third of the country's railway network, transport experts believe reopening the disused lines could solve the current gridlock.

Some say it sounds potty, but the idea is to lay thick rubber mats on former railway tracks so they can be shared by light rail and cars. It is no small irony that Bristol's railway infrastructure - drastically pruned by the "Beeching Axe" - is now being hailed as an answer to our traffic problems.

Dr Richard Beeching was part of an advisory group set up to help the 1950s Government modernise the country's public transport.

Later appointed chairman of British Railway, in 1963 he decided it was not being used enough, and embarked on a massive closure programme. It was argued at the time that buses to replace trains would be just as effective - and cheaper.

Forty years on, anyone who commutes into Bristol every morning knows just how effective the city's public transport system has become.

But the problem with deciding to reopen the railways now is that many have been built on or returned to farmland.

Some are still used to carry freight, but doubts have been raised as to whether they would be wide enough to accommodate both light rail and cars. And many of the former tracks are now used as cycle paths - which would hardly be safe for cyclists if trains and cars shared the same route.

Alan Matthews, a former director of Avon Valley Railway and the current chairman of the Portishead Railway Group, which campaigns for the former line to Portishead to be re-introduced, said the city was still suffering from the closures in the 1960s.

He said: "It's a real shame they were closed. They could have at least kept the strategic routes, because they go straight into the centre of the city.

"Public transport has to get people from A to B quickly. We have to have routes in Bristol for fast public transport. People living outside need to get in quickly, but people coming into Bristol are finding themselves stuck in a queues of traffic.

"Portishead is being built up but on the roads there is only one way in and out. There's a huge jam in the mornings. It can take an hour to get out.

"Rubber roads would not work on the Portishead line because it is single track a lot of the way, including the tunnels, so how would you keep the cars and the trains separate?

"It may work on the double track at Mangotsfield to Yate, but I find it difficult to imagine the concept in use, with the dangers of running cars and trains on the same track.

"Once cars start to use track, we end up with the same situation as in Bristol, where the buses are held up because they are using the same space as cars."

The 'rubber roads' system would use mats made from recycled car tyres, which would be laid over sleepers on disused or rarely-used railway lines. The designers of the rubber roads say they could significantly ease congestion and make light rail routes feasible and affordable. It is thought many of the road routes would become toll roads, financing themselves as well as cutting car numbers on busier, major routes.

Each mile would cost £1.4 million to build, instead of the £20 million needed to construct the same length of a modern motorway.

Brian Lomas, local representative of the Light Rail Transit Association, said: "In many cases, the railways have regrettably closed. Sometimes there aren't the passengers to support it, but a few of them were closed for the wrong reasons.

"Much of it is cycle track, and getting it back from the cyclists would be very difficult.

"The rubber roads could be used on some existing routes, but in this country making these sorts of changes seems very difficult because of bureaucracy. There are safety concerns, the need for advanced signalling. It's a good idea in the right circumstances but we have got to be careful.

"People talk about the line to Portishead because they are huge difficulties trying to get in and out of the town.

"There's freight, so it could share with passenger trains. That would make it possible for a passenger service about twice a day, but really it needs it needs to run every 10 minutes, which means freight would have to be reduced."

The main cycle route out of Bristol, going all the way to Bath, is on a former railway track, but that is now the flagship of Sustrans, the charity which promotes cycling. It is understandably reluctant to see cycle paths returned to railway use, or shared with cars.

Gill Harrison, of Sustrans, said: "The national cycle network began in Bristol. It's a flagship for us.

"It shows what you can do with disused railways. We use them because they're flat and good for cyclists. We would not want to see cars on them. We're not sure how it would work."

In fact, nobody seems exactly sure how rubber roads would work. But that does not mean new ideas on how to solve Bristol's transport crisis should not be discussed.