The London Underground doesn’t have to necessarily be a system of trains. That’s the argument presented by NBBJ, an architecture firm (and the designers behind the shadowless skyscraper), which has proposed replacing one of the city's subway lines with a moving walkway. 

The plan focuses on swapping out London Circle Line’s 17 miles of train tracks for three different lanes of travelators, like those common to airport terminals. Each lane would move at a different speed, so you could enter the track at the slowest (3 mph) and move your way up to the fastest (15 mph).

The designers posit that this mode of travel would actually be faster than the current train route, which reaches 20 mph at its fastest point, and is often overcrowded and delayed. Trains must come to a full stop for passengers to exit, but a moving walkway never stops, meaning that people who don’t want to get out at a particular station would continue on their way seamlessly. Those who want to exit would merely move over to the slow lane and step off onto a platform. (Unlike airport people movers, these wouldn’t end every few feet to allow passengers to exit.) The design even provides a moving bench for those who can’t stand up for their entire route. And for those who are willing to stand and walk the whole way, it provides a novel way to get moving during the commute.

“NBBJ was inspired to develop this concept to open new possibilities for putting the fun back into traveling on the Underground, for tourists and Londoners alike,” the firm explains in a press release. The concept would affect some 114 million Circle Line passengers per year.

The Circle Line's Notting Hill Gate station (pictured in the concept image above) as it looks today. Image Credit: Timitrius via Wikimedia Commons // CC BY-SA 2.0

NBBJ isn’t the first architectural firm to propose a radical reuse of some of London’s underground infrastructure. Gensler, another design firm, recently proposed turning a disused series of London subway tunnels into a cycle highway and retail hotspot. It’s not likely that London’s going to tear down its transit infrastructure and totally rethink how it moves people around the city, but it is facing a major challenge in transportation. The city predicts that by 2050, an increase in the city’s population and its demand for public transit could increase rail trips by up to 80 percent [PDF]. Maybe London could use some radical transportation ideas after all.

All images courtesy NBBJ unless otherwise noted.