Britain’s road network is growing 15 times faster than the rail network, according to official figures which undermine the Government’s claim that it is helping people to switch from cars to trains.

On the eve of what ministers are hailing as their “green Budget”, statistics seen by The Times show that more than 405 miles of motorway and trunk road have opened since 1997 compared with just 27 miles of railway.

In five of the past eleven years, no track was added to the domestic rail network, and in the peak years for rail growth, in 2001 and 2002, the network grew by only six miles a year.

In contrast, the system of main roads has increased by up to 85 miles a year and is forecast to grow steadily. Last week, Ruth Kelly, the Transport Secretary, announced plans for opening the hard shoulder as a running lane on up to 500 miles of motorway.

The figures, obtained from parliamentary answers by the Liberal Democrats, were revealed as Alistair Darling prepares to deliver what is being promoted as the greenest Budget yet.

The Times understands that Mr Darling was last night considering delaying the 2p-a-litre fuel-duty increase due next month but will confirm higher taxes for gas-guzzling cars. No significant measures to benefit rail passengers are expected. Last year Mr Darling introduced a mini fuel-duty escalator, under which duty would rise by 2p a litre for three years – 2p last October, 2p next month and 2p in April next year.

Since his announcement pump prices have passed the £1-a-litre mark and carried on rising. Drivers in many parts of the country now pay £1.10 a litre. Oil prices continue to edge upwards and the summer driving season in the US, which pushes up prices each year, starts in three months’ time.

The Highways Agency has 40 large-scale road schemes in various stages of development but the only significant new rail line being planned for England is Crossrail, which has been debated for more than 20 years and will not open before 2017.

The Liberal Democrats said that £11.5 billion had been spent on new roads since 1997 but only £1.16 billion on new rail lines. Norman Baker, their transport spokesman, said: “These figures show that behind their green façade, the Government has been pursuing the same old unsustainable Tory policy of treating new roads as investment and new rail as subsidy.

“Their transport policies are unnecessarily increasing carbon emissions and undermining the fight against climate change. The Government must know by now that it cannot simply build its way out of congestion. What we need is a programme of rail investment which includes new and reopened track and stations, and without which overcrowding on our railways will become intolerable within ten years.”

Only 6 per cent of the total distance travelled is by train but rail-passenger miles are growing four times faster than road traffic.

Since 1997, rail-passenger miles have risen by 50 per cent and road traffic by 12 per cent.

The Department for Transport’s 30-year rail strategy, published last July, focuses on making better use of the existing network by lengthening trains and removing bottlenecks. It ruled out “developing or opening new regional lines” for the next seven years and said a decision on whether to build a high-speed north-south line would not be made until 2012 at the earliest.

The overall cost of motoring fell in real terms by 10 per cent between 1997 and 2006, according to the department, while the cost of rail travel rose by 6 per cent and bus travel by 13 per cent.

The figures obtained by the Liberal Democrats were for the domestic road and rail networks and did not include the 68-mile Channel Tunnel rail link which fully opened in November.

A department spokesman said that it was spending £10 billion between 2009 and 2014 expanding the capacity of the rail network, including 1,300 extra carriages.

He added: “Local authorities can fund line reopenings if they believe this is the best way of addressing local transport issues.”

Network Rail said in January that Britain would need up to 1,000 miles of new high-speed line by 2020, with a new line from London to Glasgow via Birmingham and Manchester; London to Edinburgh via Leeds and Newcastle upon Tyne; and London to Cardiff via Bristol.

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