London transfer: is it time to kill off the Heathrow Express?

If Heathrow finally builds its third runway, Londoners can expect hundreds more planes flying overhead each day. But greater congestion on the ground will be a problem too. Under Heathrow’s £33bn expansion plan, 100,000-200,000 more passengers would eventually be travelling to or from the airport each day.

The most eye-catching problem has been moving part of the UK’s busiest motorway, the M25, to make space for a new 2.2-mile (3.5km) runway. A thornier one may be getting motorists out of their cars, and finding more sustainable ways for the extra passengers – and thousands of staff – to travel to and from Heathrow.