The government has announced a series of plans to help improve the UK’s transport infrastructure, including support for a third runway at Heathrow Airport.

Measures announced by transport secretary Geoff Hoon include up to £6bn to be spent improving roads; the creation of a new company - High Speed 2 - to help consider the case for new high-speed rail services between London and Scotland; and further work exploring the case for electrifying the Great Western and Midland Mainline railway lines.

Government support for a third runway at Heathrow Airport does not include 'mixed mode', which would have seen the two existing runways used more intensively, and further caveats have been put into place to ensure the UK meets its climate change commitments. These include reducing UK aviation emissions below 2005 levels by 2050 and putting a limit on initial use of the third runway so that the total increase in flights does not exceed 125,000 a year.

Extra capacity for the new runway will be subject to approval by the government after a review in 2020 by the Climate Change Committee.

‘Heathrow is vital to our economy,’ said Hoon. ‘But for too long it has operated at full capacity, losing ground to international hub airports in other countries, and with relatively minor problems causing severe delays to passengers.

‘This third runway will help secure jobs now and in the future and ensure that Britain remains a place where the world can come to do business. However, we need to do more than just improve Heathrow to ensure that Britain's economy can cope with the transport demands of the 21st century.

‘A new rail line between London and the West Midlands approaching London via a Heathrow International interchange would enable faster journeys to the north and Scotland, and could link the airport with rail destinations throughout the UK. This would unlock Heathrow for the rest of the country, making it a truly national asset. I expect to receive advice from High Speed 2 by the end of the year on a credible plan for a new line with financing proposals.

Reaction to this announcement has been mixed.

John Ling, head of transport at the Institution of Mechanical Engineers, said: ‘The concept of building additional runways appears to be at odds with the government’s commitment to reduce emissions by 80 per cent by 2050. However, with Heathrow operating at 99 per cent capacity and with aircraft stacking up waiting for landing slots, we believe that a third runway is necessary to get them out of the sky and allow flight optimisation and hence reduce emissions.’

Lord Chris Smith, chairman of the Environment Agency, expressed concerns about air quality around Heathrow but acknowledged the government’s commitment to strict legal limits on air pollution.

‘Under the new powers given to the Environment Agency as the independent regulator, we will make sure these limits are strongly and rigorously enforced,’ said Lord Smith.