The UK is backing a $US22 billion (NZ$30.7 billion) expansion of Heathrow Airport, ending 25 years of indecision and promising to boost global trade links following the vote to leave the European Union.
Heathrow, Europe's busiest airport, defeated a proposal from smaller rival Gatwick and will secure the first new full-length runway to be built near London in 70 years after environmental and political protests scuppered previous attempts.
Prime Minister Theresa May, a former critic of Heathrow expansion, said she had opted for a plan that would boost the economy, create jobs and provide access to global markets.
But her decision put her on an immediate collision course with senior politicians, including Foreign Secretary Boris Johnson, who opposes the plan.
Mr Johnson said in 2015 that he would “lie down in front of the bulldozers” to block construction of the runway – though bookies gave 33/1 odds of him actually fulfilling this promise.
The decision to jump-start one of Europe's biggest infrastructure projects is one of May's most significant moves since she took office in July and follows her approval in September of a $US24 billion (NZ$33.5 billion) nuclear power plant at Hinkley Point.
By choosing to build a third runway at Heathrow, which will require rebuilding parts of the motorway circling the capital, May opted for the more expensive and complex option over cheaper plans to extend an existing Heathrow runway or build a new one at Gatwick, south of London.
According to a three-year study by Britain's independent Airports Commission, a new runway at Heathrow would create 70,000 new jobs by 2050 and increase gross domestic product by between 0.65 and 0.75 per cent over the same period.
It will also enable Britain to keep pace with Europe's biggest airports in Paris, Amsterdam and Frankfurt, which boast greater capacity, while Heathrow's established links with emerging markets were seen to strengthen its case in the wake of Britain's June vote to leave the EU.
But within hours of the decision, politicians were lining up to denounce it.
Mr Johnson said a third runway was "undeliverable" and "very likely to be stopped" while London Mayor Sadiq Khan said he would continue to oppose Heathrow's expansion.
Zac Goldsmith, a lawmaker in May's Conservative Party, was expected to resign over the issue, causing a local election in his constituency near the airport and potentially threatening May's already slim majority in parliament.
Adam Marshall, director general of the British Chambers of Commerce, said governments had prevaricated for too long.
Heathrow is owned by Spanish infrastructure company Ferrovial, Qatar Holding, China Investment Corp and other investors, and the bill for expansion will be paid for by the private sector, with the government expected to pay for some of the additional road and rail costs.
Engineering firms Arup and US-headquartered CH2M, British construction company MACE and construction and project management firm Turner & Townsend are already working on the early stages of the project.
The government also proposed legally binding noise targets to provide respite for local residents and Heathrow will also need to meet air quality rules as a condition of planning approval.