INTRODUCING European style double decker trains between Glasgow and Edinburgh would help solve Scotland’s rail crisis, former Transport Minister Alex Neil has said.

However, union leaders described the idea as 'pie in the sky'. The cost of such an endeavour would be enormous as tunnels would have to be heightened or rails sunk lower in the earth to accommodate the kind of two-level trains seen in places like the Netherlands and Germany.

However, Neil said rail renationalisation would allow Scotland to pursue such radical innovations, as well as bring in “Ryanair” style cut price fares during off-peak hours.

The former SNP cabinet minister said having double decker services on key routes would end chronic overcrowding and raise additional funds to deliver improvements.

Neil called for the overhaul of Scotland's train services, as the latest Sunday Herald State of the Nation article today explores whether nationalised trains would deliver improvements to the crisis-hit service.

Passengers should also be able to check their luggage in at stations at the start of lengthy rail journeys along similar lines to the way people do ahead of flights at airports, he added.

The SNP MSP for Airdrie and Shotts, backs nationalisation, but stated: "The idea that you can only get innovation with the private sector is rubbish.”

He said dramatically cutting off-peak fares to Ryan Air levels, where passengers pay single figure sums to travel as part of the Irish airlines' 'no frills' policy, would “fill the trains” at times when they were traditionally less busy.

Neil, who served in Alex Salmond and Nicola Sturgeon's cabinets, also said discounted rail should also be offered to all people at off-peak hours to boost passenger numbers.

He said a publicly owned railways could introduce the changes as profits would no longer have to be paid out to private firms and could instead be invested in services.

However, he also claimed double decker trains would swell passenger numbers and lead to a growth in revenue.

He said: "It’s about having a virtuous cycle rather than a vicious cycle."

Neil said Scotland now had the opportunity to forge a new approach to railway ownership, as an alternative to privatisation and the old-style nationalisation.

Backing a continental style railways, he said the main commuter service should be publicly owned, but that private operators could have a role at a more local level.

He said: "There are different ways to skin the cat. It doesn't mean you are going back to the bad old days of British Rail. You learn from your counterparts on the continent."

Neil pointed out that double decker trains were commonplace in nations such as Holland and Poland.

He said adopting that system in Scotland, particularly along the main routes, would transform the way rail services are delivered.

Neil said: "Recently, I was in Warsaw going to Krakow and was on a double decker train. You could have Glasgow to Edinburgh double deckers.

It means you can double the capacity on each train.

"If you invest the (network's) profits in running a double decker service, it would end overcrowding, would be more convenient and would mean more money could be invested."

Neil said the electrification of rail services between Glasgow and Edinburgh would make it easier to deliver double decker trains due to the more modern network.

However, Kevin Lindsay, Scottish secretary of train drivers' union Aslef, said the rail infrastructure was not strong enough to cope with double decker services, as he called for the cash to be invested elsewhere.

Lindsay said: "It's a pie in the sky idea as the infrastructure can't take it and you would need to lower the tracks. It's a great idea in theory and I'm not against it in principle, but it's virtually impossible.

Meanwhile, Neil also suggested the super fast Japanese magnetic levitation trains, which use electrically charged magnets to lift and move carriages above the rail tracks, could be used in Scotland as part of a radical vision for nationalised rail.

But he said that change would have to be in "the longer term" once the nationalised rail service had become much more financially sustainable.