We’ve had suggestions for a cycle highway along the Thames and another in the sky; now yet another innovative scheme has been launched to help people travel around London – a moving walkway following the city’s underground Tube network.

The concept has been designed by architecture practice NBBJ to reinvigorate urban mobility in the capital, which suffers from overcrowding and congestion during rush hours.

The studio wishes to replace trains on the Underground's Circle Line with three side-by-side electronic walkways – similar to those used at airports – moving at varying speeds around the 17-mile (27km) route.

Each ‘travelator’ would increase in speed from its adjacent walkway. Commuters would enter at the slowest speed of 3mph (4kph)and slowly increase their pace moving outwards onto the fastest lane, which would reach a top speed of 15mph (24kph).

NBBJ claim that when added to the average walking pace of 3mph, pedestrians would actually move faster on foot than today’s eight Circle Line trains, which travel at 20mph (32kmph) but have to stop at stations.

In a statement, the studio said: “The result would be considerably quicker, more enjoyable and healthier journeys.”

In a separate development, Transport for London has published a new map showing the time it takes to walk above ground between almost all of the stations on the Underground network, in a bid to get more people to walk instead of taking the train. That move followed hot on the heels of a University of California study showing that cities which foster physical activity enjoy economic benefits such as higher retail revenues and lower healthcare and crime costs.

NBBJ, which is based in London, is developing a reputation for its outside-the-box thinking. In March, the firm revealed their concept for ‘shadowless skyscrapers’; a way of utilising mirrors and design software to reflect dispersed sunlight onto the streets below tall buildings.