Heathrow Airport has formally advanced its long‑pending expansion by submitting “shovel‑ready” plans for a third runway, forming the core of a £49–50 billion private investment plan designed to double its annual passenger capacity and deliver substantial economic growth. The proposed runway, measuring approximately 3.2 km and routed across a diverted M25 motorway via tunnel, is projected to allow more than 750 additional flights each day. That would raise the airport’s capacity from around 84 million passengers per year to as many as 150 million, positioning it among the world’s largest aviation hubs. The operators estimate the scheme could create or support over 100,000 jobs across the UK.
The plan encompasses £21 billion allocated to constructing the new runway itself, with £12 billion earmarked for expanding Terminal 5 facilities, and a further £15 billion dedicated to modernising broader airport infrastructure including transport links and airfield enhancements. Heathrow airport has already begun rolling out infrastructure improvements within its existing boundary—including upgrades to Terminals 2 and 5, reconfigured aircraft stands, and improvements in passenger resilience and sustainability—as part of an incremental investment programme announced earlier in 2025.
Chief Executive Thomas Woldbye emphasised that Heathrow Airport is currently operating at full capacity, and said that with the appropriate government backing—particularly on regulatory arrangements and updated airspace operations—the airport is ready to begin mobilising immediately. Commenting on the M25 relocation, Woldbye claimed it could be re‑routed “overnight” via the tunnel, although external observers have questioned the feasibility of such rapid engineering moves. Heathrow is pressing for guaranteed policy support, including the ability to recover its investment through airline charges and a modernised regulatory framework.
The timing aligns closely with political developments: in January 2025, Chancellor Rachel Reeves formally invited Heathrow to submit proposals by summer. She has since endorsed the expansion as part of a broader industrial strategy to promote economic revival, trade, and connectivity. The Labour government is concurrently pursuing legislative changes aimed at accelerating major infrastructure decisions through streamlined planning processes and infrastructure bills.
Business groups and unions—including the CBI, MakeUK, British Chambers of Commerce, and small business federations—have voiced strong support for the project, saying the third runway would unlock new markets, stimulate private investment, and support jobs across the country. Airlines such as easyJet have expressed optimism that the extra capacity could enable them to operate more extensively from Heathrow and offer lower fares to consumers.
Yet opponents argue the expansion presents serious environmental and community threats. Critics, including the Mayor of London Sadiq Khan, Greenpeace, Friends of the Earth, and the “No 3rd Runway Coalition,” warn that the development would generate substantial CO₂ emissions, noise pollution, and degradation of air quality—contradicting the UK’s climate objectives. Some also question the financial viability of the plan, referencing past failures and cost escalation—from earlier estimates of roughly £14 billion to the current £21 billion just for the runway, with affiliated infrastructure and inflation compounding risks.
Heathrow has argued it remains committed to meeting environmental thresholds set out in the Airports National Policy Statement—covering limits on carbon, noise, and air quality—and insists the expansion can proceed responsibly. Meanwhile, rivals such as the Arora Group have tabled alternative, less costly runway schemes, though Heathrow maintains those proposals lack sufficient scale or policy support.
The government plans to complete a review of all proposals over summer 2025, with a formal decision anticipated in September. Heathrow is targeting planning approval by 2029 and eyeing runway operations by around 2035, though earlier documentation had suggested completion by 2040 under previous timelines.
