From the Wikipedia article:
“The trottoir roulant rapide was an experimental high speed moving sidewalk in Paris, France, moving at a speed of 9km/h. Users first entered a slower tape, than a faster one, the two have metal rollers in between. It has produced some injuries, and is not handicap compatible. Today it is converted into an ordinary walkway running at a slower speed.”
This was an interesting innovation in transportation. It’s somewhat disconcerting that it failed only because very few users were unable to keep their feet still when being accelerated by the metal rollers to a speed at which it was safe to step on the walkway.
