It takes a lot to get us Brits to leave our cars at home. On a blistering hot day like yesterday, an air- conditioned, fast-track train might just have tipped the scales.

It takes a lot to get us Brits to leave our cars at home. On a blistering hot day like yesterday, an air- conditioned, fast-track train might just have tipped the scales. And the fact that it would have also been kinder to the environment would have been an added bonus.

But unreliability, expense, indirect routes and ageing rolling stock on some lines means we are less likely to give up the relative luxury of our cars - and until these issues are tackled, the situation, whether it is bad for the environment or not, is unlikely to change.

Another problem, according to a study commissioned by the Rail Maritime and Transport Union (RMT), is that the role the railways could play in developing more sustainable communities and transport is being ignored.

The Institute for European Environmental Policy said the environmental impact of railways had been "neglected" in the UK, particularly compared with road transport.

Prior to privatisation, the railway industry took an active lead on environmental issues such as energy use, said the report.

It went on: "Since privatisation, however, the fragmented nature of the railway industry has resulted in less priority being given to environmental concerns."

And this is to our shame.

Keith Tovey, CRed (HSBC) director of energy science based at UEA, has conducted studies on train emissions of the greenhouse gas carbon dioxide - one of the main causes of climate change.

He said: "If you drive an average car to London by yourself, you would emit 31kg of carbon dioxide or the equivalent of 3,100 party balloons full, but if you took a train, depending on differential loading, it would work out at about 7kg of carbon dioxide or 700 balloons."

Car use is higher in the UK than in any other EU state.

The report added: "It is difficult to identify one single cause for this, but a more proactive and integrated approach is often taken towards the provision of public transport on the Continent.

"The UK, for example, has very few high-speed rail lines, whereas in France, by contrast, the provision of these has been used to help revive areas in industrial decline such as Lille."

The report said the policy framework in the UK ignored the potential role that rail could play and said that the "much-heralded" integrated approach to transport after Labour was returned

to power at the end of the 1990s had

not been translated into practical action on the ground.

"This failure has been criticised time and again by experts and parliamentary select committees but with seemingly little impact on government policy," said the report.

Bob Crow, general secretary of the RMT, said at the union's annual conference in Dublin: "This is the clearest call yet for joined-up government to harness the environ-mental advantages that rail offers.

"Fragmentation and the self-interest of private operators and infrastructure companies are barriers to achieving the sustainable transport development Britain needs."

There is no doubt that rail travel passenger numbers are rising: a billion trips were made in 2005 - up by more than a third since 1997.

Britain's railway is the fastest growing in Europe but that means the daily experience of commuters is becoming increasingly fraught.

Almost three quarters of all journeys made in the East are to London, mainly at peak times.

And now Network Rail has launched a bid to get an extra £7.9bn to bring its budget up to £20.8bn - needed to combat overcrowding and congestion.

Norwich Green councillor Rupert Read said he welcomed investment in rail as long as it did not come at the expense of funding for sustainable transport.

"Travelling by train is not the greenest form of transport - it is greener to go by bike or boat - but that is not possible over longer journeys," he said.

The Green Party advocates renationalisation of the railways and sees it as the only way that proper investment can be reached.

Perhaps the point is best made by shadow transport secretary Chris Grayling.

He said: "Network Rail is basically saying that it needs either much higher fares or a big jump in its subsidy from the taxpayer if it is to tackle the growing problem of congestion and overcrowding on our railways.

"But the rail network has already had billions of pounds extra from the taxpayer in the last few years.

"We need better value for the money we are already spending, and should not just carry on pouring cash into what is increasingly looking like a financial black hole."