The Conservatives have said they will scrap plans for a third runway at Heathrow and build a high-speed rail line from London to the north of England instead. Here is a selection of reactions, compiled by Mark Lobel.
THERESA VILLIERS, SHADOW TRANSPORT SECRETARY
"This country can no longer put off the decisions necessary to deliver the transport improvements we desperately need... decisions that Labour have shown themselves so manifestly incapable of taking...
"It [the high-speed rail link] will leave a lasting legacy for the future. And it will lay the foundations for a high speed network that I believe will one day stretch across the country," she added.
AIRPORT OPERATOR BAA
Business reps think both rail and air improvements are essential
"It is not clear how this proposal will resolve the lack of airport capacity, a problem which must urgently be addressed...
"The total number of flights to Manchester and Leeds/Bradford is only 13,356 or less than 3% of Heathrow's total flights. Even if every flight from Manchester and Leeds/Bradford were replaced by a new high-speed rail line then Heathrow would still be operating at 97% of capacity."
BORIS JOHNSON, MAYOR OF LONDON
"I think that it is going to be a change for the better in London."
RUTH KELLY, TRANSPORT SECRETARY
"These proposals are politically opportunistic, economically illiterate and hugely damaging to Britain's national interests. The Tories are posing a false choice - we need both more capacity in Britain's airports and on our main rail lines."
NORMAN BAKER, LIB DEM TRANSPORT SPOKESMAN
"It seems the Tories have finally recognised the need for high-speed rail and the scrapping of the third runway at Heathrow, which Liberal Democrats have long called for. However, we will have to wait and see the small print before we know if this is just another of David Cameron's empty promises."
MATTHEW KNOWLES, SOC OF BRITISH AEROSPACE COMPANIES
"It is disappointing that the Conservatives do not recognise the progress that the aviation industry has made in recent years. Restricting the growth of aviation will affect the investment that aerospace companies put into developing clean technology. This proposal is therefore a counter-productive one.
"Through technological innovation, fuel burn and therefore CO2 emissions per passenger kilometre have been cut by 70% over the past 50 years and noise has been reduced by 75% over the last 30 years. Ms Villiers' proposal ignores the fact that new aircraft, such as the Airbus A380 superjumbo, produce less CO2 per passenger kilometre than the average car that is exempt from the London congestion charge on environmental grounds."
DAVID FROST, BRITISH CHAMBERS OF COMMERCE
"This debate shouldn't be about either high-speed rail or a third runway at Heathrow. A fully thought through transport vision would recognise that improvements to both the UK's rail and air infrastructure are essential. Business understands the need to protect the environment. But refusing to listen to the needs of the economy on the issue of Heathrow expansion will hold back British business in the future."
JOHN STEWART, HACAN ANTI-HEATHROW EXPANSION GROUP
"The Conservatives realise that business is not clamouring for a third runway. What they desperately want is a better rather than a bigger Heathrow. This announcement today is good for business, good for the environment and good for local residents...
"High-speed rail has the potential to cut the number of short-haul flights using Heathrow, so freeing up space for the more long-distance flights from the fast-developing economies of China and India without the need to expand the airport."
JOHN SAUVEN, GREENPEACE EXECUTIVE DIRECTOR
"The Conservatives have recognised that decisions taken now on high-carbon projects like new runways and coal-fired power stations will make or break our chances of tackling climate change in the future. The true test of their commitment will come when, like the Liberal Democrats, this position is written into their manifesto."
STEPHEN JOSEPH, CAMPAIGN FOR BETTER TRANSPORT
"The Conservatives have responded to the fact that expanding Heathrow would break our chances of tackling climate change. In the absence of the necessary bold government transport policies to tackle climate change, the Conservatives have shown the way that is good for the economy and good for the climate."
RICHARD BROWN, EUROSTAR CHIEF EXECUTIVE
"This is a far-sighted plan that will bring benefits to travellers, regional economies and the environment alike...
"High Speed 1 (the London to Folkestone fast link) and other high-speed lines across Europe are proven successes in helping people to switch from car and plane to train, reducing the impact of their journeys. Eurostar would certainly welcome the opportunity to operate services on High Speed 2 between London and the north."
MICHELLE DI LEO, PRO-AVIATION GROUP FLYINGMATTERS
"Now is not the time to set in stone policy decisions on aviation which will have a direct impact on our ability to maintain our position in a global economy. Many thousands of jobs depend on it and inward investment will be threatened."
TONY BOSWORTH, FRIENDS OF THE EARTH
"Scrapping airport expansion plans and investing in a fast and efficient railway network is essential if we are serious about tackling climate change. UK transport policy needs a new direction. Aviation is one of Britain's fastest growing sources of carbon dioxide - cutting the growth in air travel will help Britain develop a low carbon economy and reduce our dependency on expensive and insecure fossil fuels."