It's like a moving High Line, and is still a very good idea.
Moving sidewalks are a form of mass transit that work well when the walking distance and time is just a bit too long; they are most common in airports, but could be useful in cities too. A problem with them is that people can only get on and off them safely if they are slow, and making them multi-speed is a technical challenge. Handrails are problematic as well. We have shown a modern solution from ThyssenKrupp, but engineers have been working on the problem for over a century.A Lumiere Brothers film recently restored by the Guy Jones History Project shows new views of an amazing 2-1/4 mile long moving sidewalk that was built for the 1900 World's Fair in Paris, near the end at 4:48. Matt Novak of Paleofuture found a description of it in a book about the fair:
The rolling platform, trottoir roulant, is the special contrivance. It is not a detached structure like a railway train, arriving at and passing certain points at stated times. In the Moving Sidewalk there is no break. In engineers' language, it is an "endless floor" raised thirty feet above the level of the ground, ever and ever gliding along the four sides of the square—a wooden serpent with its tail in its mouth. It is about two and a quarter miles in length. There are ten entries to it and as many exits from it, distributed over the river face, along the Champ de Mars and the Invalides. It never stops for passengers; you step on or off as you do on or off a bus in motion, but with the important difference that the rolling platform is only two inches above the level of your shoe soles, and that its rate of motion is slower.
Note the round sections connected to straight sections, which let it go around corners and curves. Matt Novak says it was nicknamed "the wooden serpent."
The Paris sidewalk solves multi-speed problems by having two sidewalks; you first step onto the narrower, slower sidewalk and then transfer to the faster one. It solves the handrail problem by not having one; there are posts you can hang on to, but most people seem to be ignoring them.
The outer platform, as represented in the photograph, is stationary, the one next to it moves at the rate of about two and one-half miles per hour, while the one at the top moves at twice this rate of speed. This arrangement, together with the balancing posts stationed conveniently along the margins of the platforms, enables visitors to step from one to the other with the utmost ease and safety, and at the same time to regulate their progress according to their wishes.
Apparently getting there was half the fun, putting the sidewalk up high and outside so that you get a view as well as a trip. It is like the High Line in New York City, providing a different perspective.
This view represents the movable sidewalk passing through a grove of trees, at a sufficient height to enable the visitor to look down on the roofs of some of the lower buildings. The sensation of moving through the branches of trees while standing upon an apparently stationary platform of boards, is both novel and peculiar, and the enjoyment is so acute that many visitors take special trips on the rolling sidewalk for the pleasure it affords.
Really, transportation should be about more than just getting from A to B; it should be a pleasure as well. Going five miles per hour through Paris was probably a joy. They kept the Eiffel tower from the exhibition; it is too bad they didn't keep this, a sort of moving High Line that is both transportation and entertainment.
A few years ago we showed a not nearly as good video of the sidewalk filmed by Thomas Edison: