Thousands of miles of railway track will be electrified under a government plan to reduce carbon dioxide emissions from transport.

The Midland Main Line and the Great Western Main Line, currently used by diesel trains, are likely to be converted to electricity over the next decade.

At present only 40 per cent of the 20,000-mile network is electrified, one of the lowest levels in Europe.

Lord Adonis, the Transport Secretary, pledged a “major programme of electrification” today as part of his department’s strategy for reducing CO2 emissions from transport by 14 per cent by 2020.

He also announced a tough emissions standard for cars that will qualify, from 2011, for purchase grants of up to £5,000. Only electric and plug-in hybrid cars that emit 75g per km of CO2 or less will be eligible.

There are a handful of small electric models with a limited range that will qualify but no hybrids, which are far more practical. The best performing existing hybrid, the 2009 version of the Toyota Prius, emits 89g/km.

Lord Adonis announced a new emphasis on “reducing the need to travel”, a phrase the Department for Transport has avoided using in the past five years as it has concentrated on enabling greater mobility.

Much of the low-carbon transport strategy, published today, focuses on measures to encourage walking and cycling for short journeys.

The document says that 21 per cent of CO2 emissions from transport arises from journeys of less than five miles.

Lord Adonis said: “Transport accounts for a significant amount of our domestic emissions. Therefore decarbonising this sector has to be front and centre of efforts to meet our obligations and commitments to tackle climate change.

“Our strategy sets out a long-term vision for a fundamentally different transport system in our country, where carbon reduction is a central consideration in the way we do business.

“If we are to safeguard the future of transport then we must also safeguard the environment that it impacts upon — I am determined to do that.”

He said the strategy would save an additional 85 million tonnes of CO2 over the period 2018-22.

His department forecasts that the number of rail passengers will double over the next 30 years.

Lord Adonis confirmed plans to spend £5 million on improving cycle parking facilities at rail stations.

Although about 60 per cent of the population lives within a quarter of an hour cycle ride of a railway station, only 2 per cent of journeys to and from stations are made by bike, the document says.

The strategy also suggests that advanced speed limiters could reduce emissions from cars by cutting the number of drivers who break the 60mph and 70mph limits. However, the department said it had no plans to make the limiters mandatory.

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