The UK government and Heathrow Airport Limited (HAL) are pressing forward with long-debated plans to construct a third runway at London Heathrow, a project framed as central to sustaining the UK’s aviation capacity and economic growth, yet fraught with technical, environmental and social complexities.

The evolving planning statements underscore how surface access, congestion and decarbonisation requirements now sit at the heart of the policy and regulatory debate.

Over the summer of 2026, the Department of Transport will publish the draft Airports National Policy Statement (ANPS), with the Civil Aviation Authority determining if private investment will be forthcoming.

This places pressure on promoters to demonstrate how expansion will address not only economic growth and connectivity, but also the practical implications for surface transport infrastructure and carbon emissions.

The ANPS will come after Heathrow Chief Executive Thomas Woldbye said of January’s record figures: “I am proud of the strong service, great value and unrivalled global connectivity Heathrow provides to our customers.

”We remain Europe’s largest airport, but latest figures show we may lose that position in 2026 and we cannot keep driving growth for the UK economy without more capacity. 
 
“That’s why Heathrow expansion is so critical.”

Meanwhile, a June 2025 letter to potential promoters from the Transport Secretary set out core assessment criteria for proposals, requiring evaluation of “air and noise pollution”, “decarbonisation targets” and “surface access mode share targets… covering changes to highways [and] rail”.

From Heathrow’s perspective, the planning ambition is clear. In September 2025, HAL released its proposal to avoid disruption and congestion on the close-by M25.

“The new future-proofed section will be built ‘offline’ on land 130 metres to the west of today’s motorway, keeping construction separate from daily commuters.

“Traffic will then be switched from the old route to the new using carefully planned overnight closures. Once the new tunnel is complete motorists will benefit from a wider and safer stretch of motorway,” a press release claimed.

Technical and community scrutiny

Yet the proposal sits against a backdrop of technical and community scrutiny. Congestion impacts remain a central concern, not just on airport site operations but across surrounding road networks, commuter corridors and public transport systems, once the expansion is finished.

Today’s surface access modelling will need to justify any assumptions about modal shift, capacity enhancements and rail connectivity if net increases in passenger and staff journeys are to be absorbed without gridlock.

Tangentially, environmental targets, particularly the UK’s legally binding Net Zero by 2050 commitment, loom large over the planning process. While HAL’s plan asserts full compliance with legal air quality limits and integrates biodiversity conservation into its design, critics say the focus on operational carbon reduction within the airport precinct does not fully address the larger aviation emission baseline tied to greater flight numbers enabled by a third runway.

Local political resistance remains strong. Richmond Council has reiterated its “clear and unwavering opposition” to any expansion that could “worsen disruption for residents,” adding that: “The government may have chosen to reboot Heathrow’s expansion agenda, but we will not stand by while the noise, pollution and congestion problems our communities already face are made even worse.”

This tension between national infrastructure planning objectives and local environmental and congestion impacts highlights the balancing act now required as Heathrow’s third runway proposal moves through detailed planning examination. Surface access strategies, carbon accounting methodologies, and transport network modelling will be critical in ensuring that expansion can be implemented in a way that aligns with national economic policy, local quality-of-life concerns, and the wider environmental issues.

Read more: ‘Growth agenda must be consistent with a credible roadmap to Net Zero,’ say transportation professionals.

Image: passenger plane approaching London Heathrow Airport above busy motorway M25. Credit: Shutterstock.