Despite their popularity in science fiction, moving sidewalks have yet to find their place in the world. The car is still king, even in congested cities.

But researchers at the Swiss institute, Ecole Polytechnique Federale de Lausanne, think moving walkways could have a place in urban centers. As part of the institute's Post Car World project, which uses data and simulations to understand how a world without vehicles might work, Riccardo Scarinci and his colleagues present research that makes the case for moving walkways. Their analysis, based on the latest technological advances and a case study from the city of Geneva, Switzerland, shows that a network of moving walkways could shuttle 7,000 people per hour.

The first moving walkways appeared at the World's Fair in Chicago in 1893 and then seven years later at the fair in Paris. But aside from a few uses around the world, mainly indoors at airports, moving walkways have not been exploited. But as cities become more congested and the pressure increases to reduce traffic as well emissions, moving sidewalks could become a viable transportation alternative, say Scarinci and his colleagues.

Replacing vehicles requires two changes: one to the city's infrastructure and another to the inhabitants' cultural values.

For the infrastructure, the researchers developed a network of so-called accelerating moving walkways. These walkways, installed at a handful of airports around the world, have varying speeds along the the length of the track. They move more slowly where a person enters and steps off, but speed up in the middle. The fastest ones travel at about 9 miles per hour (15 km/h).

"Fifteen kilometers per hour is around the average speed at which people travel through most large cities during rush hour," Riccardo Scarinci said in a press statement.

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The researchers then designed a network of these walkways to accommodate the transportation needs of the city of Geneva. There, commuters make a total of about 117,350 trips into the city during the morning's peak rush hour. To get around, drivers travel on three different types of roads: primary, secondary and local roads.

The researchers decided to look at what would happen if they replaced the primary roads with walkways. The optimized network they developed consisted of about 20 miles of moving sidewalks, 47 in total that crossed each other at 37 intersections and connected to secondary streets at 10 different exit and entry points called gates. Here's what it would look like:


EPFL

Because moving sidewalks are more narrow than roads — four feet wide versus 11 feet for a road, they leave room in the unused traffic lane for other modes of transportation, such as bicycles. After assessing the speeds and capacity of accelerating moving walkways, the researchers calculated that the moving sidewalks could handle 7,000 passengers per hour, versus 750 and 1,800 vehicles.

Getting city people to accept moving sidewalks as a mode of transportation will require a cultural paradigm shift, the authors say. Only a few cities around the world prohibit cars from driving downtown. Although many people ride subways and walk, many still think that traveling by car offers the most freedom. But in congested areas, where traffic jams are common and parking nonexistent or expensive, this idea is a myth.

Moving walkways could raise walking to the same speed of a car traveling during rush hour and still offer the flexibility and spontaneity of movement that driving a car does not, the researchers say.

"It might possibly contribute to liberate our cities from their twitchy rhythm imposed by car traffic into a space of continuous and unconstrained flow of social interactions," they write.

The researchers do acknowledge that the cost for converting roads to moving sidewalks could be expensive, but think that the benefits potentially outweigh the negatives. A fully electric walkway would reduce emissions and with more pedestrians walking around, the city center could become a more vibrant area with more attention given to public spaces.

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