Heathrow now considering (not tunnel or bridge) but cheaper series of “viaducts” over M25

Heathrow has a huge problem in how to get a runway over the busiest, widest stretch of the M25.  The original plan was a full 14-lane tunnel about 2,000 feet long. Then there were plans for a sort of bridge over the road. Even those would be prohibitively expensive (Heathrow says it would only pay £1.1 billion on roads etc). Now there are plans, by Phil Wilbraham, who oversaw the construction of Heathrow’s terminals 2 and 5,  to build a cheaper system. It would be 3 parallel bridges across the M25, with narrow ones for taxiways at the side, and a wider one for the runway in the centre. The plan is for a 2 mile long runway, to take even the largest planes. The main airline at Heathrow, British Airways, suggested a runway about 1,000 feet shorter, that would not need to cross the motorway, but that might not be able to take A380s, and would mess up the flight patterns.  The earlier “bridge” concept would have meant the runway would be on a slight slope, to get over the motorway. The cost of moving the thousands of tonnes of earth would be immense, and it is thought Heathrow has had to reconsider. The airlines do not want to have to pay for the building costs of roads etc associated with a 3rd runway. The government does not want to force Heathrow to pay, as this would mean increasing the cost of flying – and reduce demand at Heathrow. 


Heathrow plan to build third runway — on stilts over M25

Airport considers simpler scheme to bridge motorway

By John Collingridge (Sunday Times)
June 4 2017

It is the engineering challenge from hell: how to build a runway across Britain’s busiest motorway.

Now Heathrow airport has come up with a new cut-price solution for its £17bn third runway — a series of “viaducts” across the M25. The airport, which started out with plans for a 14-lane tunnel, then switched to a “very gentle hill”, is now considering building three parallel bridges across the M25. According to plans presented to an engineering conference, the widest viaduct would be the runway itself, while two thinner viaducts would be built as taxiways for planes.


… full TImes article at




Building third runway over M25 will ‘threaten costs’ and ‘lead to spiralling delays’ to Heathrow expansion

Excessive costs to build across the motorway should be replaced by a shorter more affordable runway, according to parent company of British Airways

25 MAY 2017 (Get West London)

Exuberant costs incurred in transforming one of the busiest motorways in London to make way for a third runway could derail Heathrow expansion, it has been claimed.

That was the stark warning made by the boss of British Airways ‘ parent company, IAG, Willie Walsh.

On top of the “inflated £17 billion bill” for an additional runway, the company estimates building across the existing M25 path would incur a surplus of £2billion to £3billion more, with “all costs paid for by airlines”.

Concerns were raised in its response to the Government’s consultation on Heathrow expansion, which is due to close at 11.45pm on Thursday (May 25).

The company believes a shorter runway that does not breach the M25, of 3,200 metres instead of 3,500 metres, would be perfectly operational.

It said in its submission that Heathrow is the best option for expansion and the consideration for a shorter runway could keep landing charges the same or lower than current levels.

Mr Walsh said: “Airlines were never consulted on the runway length and they can operate perfectly well from a slightly shorter runway that doesn’t cross the M25.

“Bridging the M25 means years of disruption on a motorway already plagued by delays and congestion.

“As well as increased costs, this will have a huge impact not only on motorists but on local communities around Heathrow.”

Mr Walsh believes expanding across the motorway, which would include digging a tunnel or building a runway over the existing road, could be costly and cause delays.

“The airport has yet to produce a business plan that assesses the financial implications and risks of bridging the M25,” he said.

“We will not pay for a runway that threatens both costs and delays spiralling out of control and where critical elements of the project could be undeliverable.”

Heathrow said a shorter runway would have a greater impact on noise in the local community.

It is claimed this is due to larger aircraft, such as the A380, unable to use it for take-offs, limiting the respite period in parts of west London.

Environmental protesters avoid jail after blocking main tunnel into Heathrow Airport by attaching themselves to a car with expanding foam
A Heathrow Airport spokesman said: “Like all major infrastructure projects, we have to balance several factors in order to deliver the increase in airport expansion that Britain needs: risk, constructability, passenger experience, quality, affordability and time.

“In each of these areas we have engaged expert advisers and consulted our airlines to ensure we get the right balance and the best outcome for our passengers, our local communities and the country as a whole.”