British Airways owner IAG has hit out again at prospective M25 plans for Heathrow expansion, warning that bridging the major motorway will derail the third runway plans.
In its submission to the government's consultation on its national policy statement, which closes tomorrow, IAG warns of the scheme's cost and complexity, estimating that bridging the M25 will cost £2-3bn on top of the airport's £17bn bill for the third runway.
IAG said there is no detailed risk and cost analysis of Heathrow's plans to build over one of Europe's busiest motorways.
Willie Walsh, IAG's chief executive, said: "The airport has yet to produce a business plan that assesses the financial implications and risks of bridging the M25. 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."
In a headache for the airline giant, it said all costs will be paid for by carriers' customers.
IAG wants the focus on a shorter runway that does not breach the M25. A shorter runway had been floated amid Heathrow's earlier proposals for expansion, but was considered more of a trouble in terms of noise concerns.
Walsh said: "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."
Britain needs cost-effective airport infrastructure that benefits the country rather than Heathrow’s shareholders.
While IAG has backed Heathrow for expansion over the other alternatives, such as a second Gatwick runway, Walsh urged the government to benchmark Heathrow costs against "other similar global schemes".
A Heathrow spokesperson 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."
The airport has not yet decided how the runway will cross the M25, with a proposal to construct a 650 metre tunnel for the motorway vying with the option of putting the runway on a slope above the road.
Transport secretary Chris Grayling said the latter would be "cheaper and quicker" than any movement of the M25 in October last year.
Highways England has also said a tunnel would cause a national shortage of contractors, delay road building schemes across Britain and cause huge frustration for drivers.