Ministers back Heathrow’s plan to move M25 for third runway

November 25, 2025 at 10:40 AM•2 min read•Christopher McKeon

UK Ministers greenlight Heathrow's £33B third runway plan, but what's the catch for the M25?

Key Points

1UK Ministers greenlight Heathrow's third runway, mandating a costly M25 motorway relocation.
2£33 billion expansion project targets 756,000 flights and 150 million passengers annually by 2035.
3UK Transport Secretary rejected Arora Group's rival proposal due to greater residential impact.
4Regulatory clarity sought by Heathrow for project's next phase, with a mid-December deadline.

UK Ministers have officially backed Heathrow Airport's ambitious plan for a third runway, a decision that necessitates the relocation of a section of the M25 motorway. This pivotal approval comes after the UK Transport Secretary, Heidi Alexander, rejected a rival proposal from the Arora Group, deeming Heathrow's own scheme as the "most credible and deliverable option" for expanding the nation's busiest airport. The move signals a significant step forward for a project poised to reshape air travel infrastructure in the United Kingdom.

The approved Heathrow proposal outlines the construction of a 3,500-meter runway, a critical component of which involves building a new M25 tunnel and bridges approximately 130 meters west of the existing motorway. In contrast, the Arora Group's alternative suggested a shorter, 2,800-meter runway that would not require diverting the M25. However, the UK Transport Secretary concluded that the Arora plan would still impose "a considerable impact" on the motorway and necessitate more compulsory home purchases around the airport, leading to its rejection.

The expansive project carries an estimated cost of £33 billion, with £1.5 billion specifically allocated for the M25 relocation. This investment aims to boost Heathrow's annual capacity to 756,000 flights and accommodate 150 million passengers. While Heathrow welcomed the decision, a spokesperson emphasized the need for "further clarity" on regulatory oversight for the next phase, urging the British Government and the UK Civil Aviation Authority (CAA) to provide definitive decisions by mid-December.

The British Government intends to finalize a planning application decision for Heathrow's expansion by the next election, with the third runway projected to become operational by 2035. This timeline aligns with the UK Transport Secretary's commitment to swiftly advance the project, realizing its potential for passengers, businesses, and the broader British economy. Further consultations are expected as the British Government revises the Airports National Policy Statement, and the independent Climate Change Committee will be consulted to ensure consistency with the UK's carbon emission reduction targets.