Revealed: How the M25 would be moved under Heathrow Airport’s plans for a third runway

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Heathrow chiefs have laid out how they believe the M25 can be moved without creating traffic chaos under plans for a third runway.

They say that a new section would be built away from London’s orbital motorway and once completed traffic would then switch over through “carefully planned overnight closures”.

However, many Londoners are likely to be sceptical about the claims, particularly given the lengthy disruption caused by improvements at Junction 10 of the M25 where it meets the A3 in Surrey.

The Government has already said it will support a third runway at Heathrow as part of its plans to get the British economy growing again (Jonathan Brady/PA)PA ArchiveHeathrow has stepped up its campaign for expansion after Andy Burnham cast huge doubt over whether his Government would back it, refusing five times in a recent interview to say that it would do so.

Sir Keir Starmer’s administration had supported a third runway as his Chancellor Rachel Reeves scrambled to find ways to boost the UK’s economic growth while hitting businesses with tax rises.

The expansion scheme, which is already estimated to cost £49 billion with terminal and other improvements, is believed to have been hit with years of delays.

London Mayor Lord Sadiq Khan is firmly against the new runway, which would increase the west London airport’s capacity to 756,000 flights and 150 million passengers a year.

Lord Sadiq Khan opposes a bigger HeathrowPAAirlines say it would be the most expensive new runway project ever and would involve moving the M25 at a cost of £1.5 billion.

As part of its renewed drive to get Government backing and the support of Londoners, Heathrow has explained how it believes that one of the UK’s busiest motorways could be rerouted without bringing traffic to a standstill.

“The answer is surprisingly simple: Build the new section of the M25 away from the existing motorway, then switch traffic across when it’s ready,” it says.

“Heathrow’s plans would see a brand-new tunnel and bridges constructed 130 metres west of the current M25, allowing most of the work to happen offline and separate from day-to-day traffic.

“Rather than years of major disruption, traffic would transfer to the new route through carefully planned overnight closures.”

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It stressed the upgrade to the motorway would be privately-financed.

The airport bosses added that they had explored other options such as building over the M4 spur.

But they concluded that this would require significantly more demolition in local communities, and create greater disruption for road and rail users during construction.

They also argued: “Building airport infrastructure over major roads has already been successfully delivered at airports including Frankfurt and Paris Charles de Gaulle.”

Heathrow claims a third runway would unlock more than 100,000 jobs and £33 billion of private investment across the UK.

However, MPs who oppose the expansion say the economic benefits would be limited, citing Government figures.

Amid the row, ministers are hiring bankers for £3 million to tell them if the economic case for a third runway stacks up.