The M25 is set to become Britain's first 14-lane motorway if a third runway is built at Heathrow Airport.
The coalition government had ruled out third runway, but the proposal just would not go away. Today, airport bosses argue the case.
Passengers using Heathrow face a rise in ticket prices under £3 billion investment plans proposed today by bosses of the airport.
Heathrow Airport has revealed it is operating on a knife edge every day - because the site is so busy, that it sometimes works close to full capacity.
Managers have said they are now introducing radical new measures to reduce daily delays and the massive chaos caused during bad weather and when things go wrong.
The changes include the installation of computer technology used by Formula One racing. Our Transport Correspondent Mike Pearse reports.
Revised plans have been announced today for a third runway at Heathrow with radical plans to put extra lanes on the M25 near its junction with the M4.
The new runway will run over the M25 which would be put in a tunnel.
Airport managers say it will be able to add extra lanes to ease the worst bottleneck on the country.
They also announced they would be place the runway further south than in previous plans to reduce the number of homes to be demolished from 950 to 750.
Those hit will get the market value and 25% of the value of their property on top. Heathrow also announced plans for direct rail links from Reading and connecting to the South West Trains network. A new runway would double flight numbers to more than 700,000.
Gatwick has said its expansion plans are cheaper and far more beneficial than Heathrow's.
Heathrow and Gatwick airports have both unveiled revised expansion plans to the Airports Commission in a bid to secure permission to build a new runway.
The west Sussex airport said expansion at Gatwick would deliver the following benefits:
- Will achieve £40 billion more in economic benefits to the UK than expansion at Heathrow
- Expansion will deliver more than 120,000 jobs in London and south east England
- Fewer people will be affected by noise pollution
- Around 10 million more passengers would be able to travel with a second runway at Gatwick each year than with a third runway at Heathrow
The Airports Commission is considering the following expansion plans:
- Heathrow Hub
- Thames Estuary
Heathrow Airport today announced what it calls an "improved third runway proposal that has been shaped by feedback from local residents and businesses."
The airport has been consulting with residents since its plan for a new runway to the north-west of the current site was short-listed by the Howard Davies Commission in December.
The feedback identified aircraft noise, air pollution, safety, road-traffic congestion and jobs as the top concerns.
As well as addressing these issues in the new proposals, Heathrow has put forward plans which it said would bring maximum benefit to the local and UK economy, adding £100bn of economic benefit to the UK as a whole and creating 50,000 new local jobs.
ITV News Meridian understands a section of the M25 will be put in a tunnel if plans for a third Heathrow runway get the go-ahead. In an announcement later, the airport will back a new runway to be built between the existing airport and the M4.
A full-length runway would need to go over the M25, which is twelve lanes wide at that point.
Heathrow will say while the tunnel is built drivers will continue to use the existing road and switch when the tunnel is complete.
A new rail hub with links to HS2, Reading and the south is also planned. Under the scheme up to 1,000 homes would be demolished. Heahthrow says it proposed to offer those affected 25 per cent more than the value of their homes. Full plans will be announced later.
Heathrow Airport is unveiling plans today for a third runway - including a sixth terminal - and plans for a major new rail hub with links from the Thames Valley to the airport.
It is backing a new runway that will be nearer Windsor next to the M4 and includes putting the M25 in a tunnel. But local people say flight numbers and noise would double and a thousand homes would need to be demolished.
Heathrow and Gatwick will submit their final proposals in the battle over expansion rights today.
They will publish their plans to the Airports Commission, an inquiry led by former Financial Services Authority chairman, Sir Howard Davies.
A decision will then be made into where the next runway in the south east of England should be built.
Video. Heathrow says it has grand plans to make sure its massive new terminal opens without the chaos that surrounded the first day of Terminal 5. Baggage belts broke and staff got lost.
The new building is called Terminal 2: The Queens Terminal and will open in three months. For the past three years, it has been the biggest construction site in Europe. The cost of the rebuild, a staggering £2.5 billion and 24,000 staff will be employed in the new building.
So, as the finishing touches are being made, our Transport Correspondent Mike Pearse has been given an exclusive look around.
He spoke to John Holland-Kaye from Heathrow Airport.