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Heathrow plans to lower M25 and divert rivers during expansion | Construction Buzz #222

19 Jun 2019

Heathrow Airport Ltd [HAL] has unveiled its masterplan to expand the airport, which includes detailed plans to lower the M25 beneath the third runway, to divert rivers and enhance surface access for transport links.

The unveiling of the full masterplan has come on the same day that HAL launched a 12-week statutory consultation on its plan to expand the airport.

According to the masterplan, the third runway will be 3,500m in length and will require the repositioning of the M25 by up to 150m to the west of its existing alignment over a length of 2km.

In its new alignment, the M25 will pass below the new runway and taxiways. The masterplan proposes that the M25 be widened and lowered by between 4m and 4.5m below its existing level. Upgrades to junctions 14 and 14a of the M25 are also planned, to accommodate future traffic requirements.

In addition, Heathrow has put forward plans for the A4 to be diverted to the north of Harmondsworth and east of Sipson to avoid the new runway and will provide replacement east-west connectivity for vehicles. Meanwhile, to fit the expanded airport to the east of the M25, the A3044 would be moved to the west of the motorway.

The masterplan also sets out HAL’s intention to divert local rivers around the new western boundary of the expanded airport, including a river corridor that passes beneath the new runway.

To improve surface access, two parkways have been proposed to the north and south of the airport to provide much of the airport’s future parking. It is planned that both parkways be constructed and brought into operation in a phased manner as the airport is expanded over time.

The proposed northern parkway would be capable of accommodating up to 24,000 cars, have access from the M4 and be connected directly to the airport’s central terminal area by a shuttle system.

Meanwhile, HAL’s planned southern parkway would provide up to 22,000 car parking spaces, be served by an upgraded road connection to Junction 14a of the M25 and be directly connected to the Terminal 5 campus by shuttle system.

In addition to the third runway, the masterplan highlights HAL’s plan to develop an enlarged Heathrow’s Terminal 2 Campus, which will replace Terminal 1 and Terminal 3. Terminal 5 will also be expanded, with additional capacity to the west of the terminal being created in the form of a new “T5X” building.

HAL claims it has prepared its masterplan to accommodate up to 756,000 flights and 142M passengers per annum and a cargo capacity of approximately 3M.t per year.

Aecom chief executive David Barwell expressed satisfaction with the masterplan, praising it as both “ambitious” and “not unrealistic”.

He said: “As with many aviation projects, Heathrow’s Preferred Masterplan is an ambitious vision. But the concept of building the third runway over the M25 is not a unique approach.

”For Fort Lauderdale Airport’s expansion programme in the United States, AECOM oversaw the extension and elevation of the runway to cross US Highway 1 and the Florida East Coast Railroad, all of which was done whilst minimising disruption to the travelling public. So whilst ambitious, it is not unrealistic.”

However, rival Heathrow expansion bidder Surinder Arora said he was “not impressed” by the masterplan.

“We are not impressed with HAL’s plan. We fail to see how they can stay within their £14bn budget or deliver it on time. It is too elaborate, almost like they want to build an entire city at the airport rather than focus on the passenger,” he said.

“We will do it for less money, quicker, and, for the first time ever, we will set a benchmark for HAL to be measured against.” 

A spokesman for alternative expansion partner Heathrow Hub added: “This third runway plan is the ultimate £30bn Unicorn and the next Prime Minister -presumably Boris Johnson - should cancel it. The idea Heathrow can get it across the M25 right next to the M4 junction without causing years of delays is fanciful.

“The costs – to be borne by passengers and airlines – are evidently spiralling out of control. And the project is hugely environmentally damaging. Far better to build our cheaper, greener, quieter extended runway instead. Politicians need to rediscover that, so often in life, the simplest, compromise solution is best.”

Heathrow Hub is a rival expansion firm which argues that extending one of the existing runways at Heathrow is a more cost-effective way of expanding the airport.

Once the consultation has finished and feedback has been collected, Heathrow will then submit its final proposal to the transport secretary in 2020. The transport secretary will then decide whether or not to grant Heathrow a development consent order, which is needed for construction to begin.

Source: New Civil Engineer

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