TfL said Heathrow had “substantially underestimated” the impact of the extra runway, as it released a figure eight times higher than the £2.2bn that the airport had calculated, reports The Telegraph.
The transport authority instead estimates that the development, which could lead to heavier congestion on London’s roads, buses and trains, will have a £18.4bn price tag.
Heathrow has previously promised that £1.2bn would be raised through public contributions, with the airport spending another £1bn, leaving a shortfall of more than £16bn.
TfL is not the first organisation to claim that Heathrow has underestimated the cost of building the controversial third runway. The long-awaited Airports Commission Report revealed that the runway would cost £18.6bn, £3bn more than the airport suggested.
Heathrow is in the midst of a head-to-head battle with Gatwick Airport for expansion. After failing to make a decision on Heathrow expansion by last Christmas, the UK Government is now expected to wait until after the European referendum in June.
The Airports Commission estimated that the cost of Heathrow expansion to TfL would be £5.7bn in its publication about the future of airport expansion released last summer. The money, it said, would be spent on renovations such as widening the M4 or creating an M25 tunnel that would go underneath the runway.
TfL’s higher figure also takes into account public transport upgrades, including changes to the South West Main Line and Great Western Main Line, and bus improvements.
Some of the work would be necessary even without the third runway, TfL admitted, while stressing that the development would accelerate the need for the upgrades.
“It is entirely in the realms of possibility that some of the schemes would be deemed necessary at some unspecified time in the future,” said a spokesman for TfL. “The point is they’re not currently envisaged – planned or committed – but if Heathrow expansion is progressed, they would absolutely be needed.”
John Holland-Kaye, chief executive of Heathrow, said TfL’s estimate was a “long list of anything that might be needed across London”.
