Heathrow outlines M25 scheme for third runway

Heathrow claims M25 drivers will be kept on the move during construction of a third runway with a new new tunnel and bridges. The new section would be built 'offline' on land 130 metres to the west of the motorway, keeping building separate from daily commuters. Traffic will then be switched from the old route to the new using "carefully planned" overnight closures.

New link roads will separate passing M25 traffic from those leaving and joining the M4, according to Heathrow which said the scheme would be privately financed by the London hub. [embedded content] Alternative options to place a new runway over the M4 spur were evaluated but discarded by both the airport and Airports Commission for having "fewer benefits and causing more disruption".

Any design that avoids the M25 would result in a runway too short to accommodate all long-haul flights, some airlines have indicated. "Building over the M4 spur would require the demolition of thousands more homes and expose more residents to noise once operational," the airport argued. Developing a new runway over a motorway is "far from new" and has been delivered at other airports including Frankfurt and Charles de Gaulle, Paris, Heathrow noted,

The impact on M25 has been one of the most common questions raised since expanding Heathrow proposals were submitted to the government. Heathrow said it will continue to work closely with National Highways to finalise the details of its plans. Surface access director Sophie Chapman said: "Heathrow expansion is a once in a generation opportunity to upgrade our connectivity in the air and on the ground.

"One of the legacies of our plan will be a 100% privately financed upgrade to one of the busiest stretches of the M25.

"We have a tested plan for building next to the current motorway that will keep motorists on the move during construction.

"We have already looked at the alternatives and they simply create more impacts for less benefits so we're confident we have the best plan available."