The airport will propose cutting 300 metres from the length of the northwestern runway, a scheme approved by the government following the Airports Commission process, in an attempt to cut costs.

Heathrow Airport has revealed its latest plans for expansion after pledging to trim £2.5bn off costs, including options on how to deal with Britain's busiest motorway and making the runway shorter.

Emma Gilthorpe, Heathrow’s executive director for expansion, said: “We need feedback to help deliver this opportunity responsibly and to create a long-term legacy both at a local and national level. Heathrow is consulting to ensure that we deliver benefits for our passengers, businesses across the country but also, importantly, for those neighbours closest to us.”

Grayling told BBC Radio 4’s Today programme: “One of the things Heathrow have been looking at is doing what many other airports have done around the world, which is to build the runway over the top of the road rather than underneath it.”

He said the government was working to make sure the third runway was affordable and a ramp was a cheaper and quicker way of doing it than tunnelling. “I am very concerned to make sure it doesn’t cause massive disruption on the M25,” he said.

Third runway at Heathrow Airport would not break pollution laws

The Department for Transport said: “In a major boost for the UK economy the government today announced its support for a new runway at Heathrow – the first full-length runway in the south-east since the second world war.”