Ever thought what the London Underground would be like to travel on if Tube trains were replaced by moving walkways?

London-based architect firm NBBJ has unveiled a radical new idea to stamp out delays on the Circle Line - by installing a three-lane travelator.

The team behind the 'walk the line' plans claim the move could help shorten people's journey times and improve their health.

Currently, the yellow line - which runs through stations including Hammersmith, Paddington, Notting Hill Gate, Westminster, and as far as Liverpool Street - carries around 114m passengers each year with trains reaching top speeds of 20mph.

The new concept would turn the 17-miles of track into a three-lane moving walkway with commuters stepping on at the 'slow' lane, which travels at 3mph increasing to 9mph; then boosting their pace by moving onto the middle lane with speeds of between 6mph and 12mph; and a fast lane with a top speed of 15mph (as pictured below).

Commuters can enter the Tube, tap their Oyster card, and walk the line on the tracks which increase and decrease speed between stations.

To disembark, people would move back to the slow lane and safely step down on to the platform.

According to NBBJ research, with an average walking pace of 3mph, passengers would actually move faster on foot than the Circle Line trains today, which stop for boarding at each station.

The idea, which would revolutionise the way people in London commute, has been inspired by the 110th anniversary of the Circle Line this year.

Christian Coop, design director at NBBJ said: "On the 110th anniversary year of the Circle Line’s electrification, we wanted to examine how to revolutionise the Underground Tube network to create healthier, more enjoyable journeys for Londoners and tourists alike.

"Similarly, we developed a 'shadowless skyscraper' design earlier this year to respond to the ongoing tall buildings debate in London.

"Our practice will continue to create ideas that encourage people to think differently about how we live, and we will continue using these ideas to inspire the real buildings we create."

Circle Line - Walk the Line

The concept of a Circle Line travelator has been designed with a mindset to put the fun back into travelling for tourists and Londoners alike.

Similar projects have taken place in Paris and Canada but never on this scale and are used more as a form of getting between two particular places rather than a form of transport in its own right.