Revealed: 11 options being considered by engineers for linking the HS2 scheme into Heathrow Airport
There are three variables that engineers are assessing: where the HS2 line will first divert towards Heathrow; where the stopping point will be near the airport; and where the loop will rejoin the main line.
The unpublished report by engineering company Arup, obtained by the Gazette, states that "tunnelling considerations are applicable to all elements". In fact, only one surface option - a spur between Heathrow and Denham is being considered.
A twin-track tunnel is also proposed, to allow trains to travel underground at speeds of up to 225kph.
Last year the Gazette reported how Arup was lobbying for HS2 to be routed through Heathrow, with a hub station close to Iver, stretching all the way across what is now mainly disused sewage filter beds belonging to Veolia Water almost to Tavistock Road, West Drayton.
This was rejected by the government last July as too expensive but would have meant a reprieve for the threatened areas of Ickenham, Ruislip and Harefield.
Now, the company at the heart of bringing the 'Heathrow loop' option to life has been tasked by HS2 with integrating the controversial rail line with the busiest passenger airport in Europe.
Arup has compared the project with the Boston Central Artery tunnel, an American scheme to build an underground highway, the largest of its type in the world.
And this equally ambitious project could have dire implications for the residents of Hillingdon borough.
Because depending on which of the 11 possible routes is chosen, areas at the heart of the borough the most densely populated parts of West Drayton, Yiewsley and Hayes - face years of disruption while tunnels are bored underneath them.
The route will ultimately come down to HS2, in conjunction with the Department for Transport, who will decide on the basis of cost, political acceptability, disruption and a swathe of other factors.
The department has been coy so far on possible routes, and has only said there could be a firm decision next year.
Denham Parish Council, just across 'the border' from Uxbridge in South Bucks, has described the implications as "extremely serious for Denham, Iver and west London".
A spokesman said: "One surface option will go through Denham, causing as much damage as a motorway. The fear is that this is a precursor to further development at Heathrow."
The least costly of the suggested routes is the Denham spur to Heathrow North, at £7.3billion, although if it was tunnelled, it would cost £7.7bn.
Keri Brennan, chairwoman of the Ruislip Against HS2 campaign group, said: "It's like they are sacrificing Hillingdon on the HS2 pyre. This borough is the worst hit in the country, with the exit route from central London and the loop to Heathrow passing through. I used to live in West Drayton, and if I was there now, I would be seriously worried about what is being proposed."
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