London architects have proposed turning the Circle Underground Line into one huge gigantic moving walkway.
The plans, imagined as part of a challenge from think tank New London Architecture for new ideas to improve life for Londoners, would make commuters happier and healthier, the designers claim.
The Circle Line is one of London's most congested, carrying 114 million people each year along 17 miles of track.
This year it celebrates its 110th anniversary since becoming electrified - but architects from London's NBBJ firm say converting it to a walking superhighway would mean it could take more people - and those travelling on it could complete their journey faster.
The travelator would consist of three lines; a feeder line moving at 3mph onto a yellow "slow lane" going at the same speed through stations but accelerating to 6mph and then 9 mph in lit tunnels.
There would also be a “middle lane” , coloured orange, with a top speed of 12mph, and a 15mph red “fast lane”.
NBBJ researchers calculate the travelator would allow up to 55,000 people to use the Circle line at any one time.