The potential scale of disruption from Heathrow Airport’s controversial expansion project has been revealed, including plans to lower the M25 for the third runway to cross, reroute rivers, replace utilities and build car parks for nearly 50,000 cars.

Heathrow, though, said expansion should “not come at any cost” and has outlined plans for low-emission zones and congestion charges to stem local air pollution. It plans to expand in phases up to 2050, with new terminal buildings added after the new runway opens in 2026, as passenger numbers reach a forecast 140 million a year.

The news comes as the airport launched a 12-week statutory consultation on expansion on its preferred masterplan for the project, with business leaders and the construction industry welcoming the plans.

Emma Gilthorpe, Heathrow’s executive director for expansion, said: “Expansion must not come at any cost. That is why we have been working with partners at the airport, in local communities and in government to ensure our plans show how we can grow sustainably and responsibly – with environmental considerations at the heart of expansion. This consultation is an opportunity for people to have their say on our preferred masterplan, so it’s really important that as many people as possible take part.”

David Barwell, chief executive, UK & Ireland, AECOM, said: “It’s vitally important to the UK economy that the expansion of Heathrow Airport goes ahead, and the unveiling of their preferred masterplan is an important step forward in making this a reality. However, I also whole-heartedly agree that the expansion must not come at any cost. I’m extremely pleased to see the importance the consultation places on working with local communities to grow sustainably and responsibly, with a strong emphasis on environmental considerations.”

Civil Engineering Contractors Association (CECA) chief executive Alasdair Reisner said: “Addressing Britain’s airport capacity gap will be fundamental to ensuring we remain globally competitive in terms of trade after Brexit, as well as boosting economic growth across the whole of the UK. Currently, the capacity gap is costing the UK an estimated £1.2bn a year. We welcome the opportunity for consultation, and look forward to the significant benefits Heathrow expansion will deliver in securing post-Brexit economic growth.”

However, the plans are set to meet serious opposition from environmental and community campaigners, with the Green Party amongst those arguing that Heathrow’s expansion plans “make a mockery of the government’s zero emissions strategy.” Jonathan Bartley, Green Party co-leader said: "We are in a climate emergency. The Committee on Climate Change has already said a net-zero carbon target means the government has to rethink aviation expansion. This is something the government has clearly failed to grasp. Its actions are a direct opposite to its words.” 

The deadline for responding to the consultation is 13 September 2019. Feedback can be submitted in a number of ways, including online. Following the conclusion of the consultation and after feedback has been incorporated, Heathrow will submit a final proposal to the secretary of state for transport in 2020. The decision on whether to grant the development consent order will be made by the secretary of state following a public examination period.