Heathrow third runway: What’s the plan for expanding the airport?

Heathrow is already the UK’s busiest airport, serving more than 80 million travellers a year with its four passenger terminals and two runways.

A third runway would mean demolishing hundreds of homes, diverting rivers, and rerouting the M25 motorway between junctions 14 and 15 through a tunnel under the new runway.

The number of flights, currently capped at 480,000 a year, could go up to 720,000 – or nearly 2,000 a day on average.

Heathrow told the BBC that it would eventually be able to serve up to 140 million passengers a year once the third runway is in operation.

The airport’s owners, which include Saudi Arabia and Qatar’s sovereign wealth funds and private equity firm Ardian, said the costs of expansion would be met by charging airlines for use of the larger airport.

But after years of wrangling over the original plans, external, the initial cost estimate of £14bn will need to be revised.