The UK government has backed a proposal by the owner of Heathrow Airport to build a 3,500-metre third runway.
The £33 billion ($43 billion) project involves moving a section of the M25 motorway and would nearly double the number of passengers to 150 million a year, cementing Heathrow's place as one of the busiest airports in the world.
Transport Secretary Heidi Alexander described the plan submitted by Heathrow Airport Limited as “the most credible and deliverable option” and said the government is acting “swiftly and decisively” to move it forward.
It includes a new T5X terminal as well as a new M25 tunnel and bridges to be built 130 metres west of the existing motorway.
A less expensive, £25 billion rival proposal from Arora Group, owned by billionaire Surinder Arora, was rejected. It would have involved building a shorter, 2,800-metre runway without impacting the M25.
“We’re acting swiftly and decisively to get this project off the ground so we can realise its transformational potential for passengers, businesses and our economy sooner,” said Ms Alexander.
She added that her department wants planning permission secured by 2029 and flights to begin in 2035.
The new north-western runway will allow the airport to increase capacity to 756,000 flights a year, almost doubling the number of passengers a year from 84 million. By comparison, Dubai International Airport handled 92 million passengers in 2024.
The project will support 100,000 jobs and Ms Alexander said it would “attract international investment and boost Britain’s connectivity”.
While Mr Arora said he accepted the government’s announcement, he said his proposal had been to “avoid the M25 and bring down both risks and costs of the expansion scheme”.
He added that Arora Group is now “reviewing how our plans will be adjusted to the longer runway scheme” and that it plans to submit a development consent order that could yet challenge the final decision.
“We have long argued that regulatory reform and the introduction of competition at Heathrow Airport is absolutely imperative to keep costs under control at the airport,” Mr Arora said in a statement.
He argued that competition was vital as the airport has “the most expensive charges in the world” and added that Heathrow Airport Limited's proposed cost “jeopardises the future of the airport as a globally competitive hub and its ability to aid the UK’s economic growth agenda”.
But Ms Alexander's department said the longer runway fulfilled “the government’s ambition”.
A spokesperson for Heathrow Airport said the expansion would mean “more connectivity, increased trade, improved passenger experience and a huge economic boost for British businesses”.
The spokesperson said more clarity on “how the next phase of the project will be regulated” is needed by mid-December to avoid further delays.
The government said the development will be carried out in line with the UK's climate obligations and take “air quality and noise obligations” into consideration.
Chancellor Rachel Reeves will deliver the UK budget on Wednesday. She said the government had taken a decision on Heathrow “where previous governments hesitated” and that the expansion would “open the door” to new investment.
