theodp writes "The real problem nowadays is how to move crowds,' said the manager of the failed Trottoir Roulant Rapide high-speed (9 km/h) people mover project. 'They can travel fast over long distances with the TGV (high-speed train) or airplanes, but not over short distances (under 1 km).' Slate's Tom Vanderbilt explores whether moving walkways might be viable for urban transportation. The first moving sidewalks were unveiled at Chicago's 1893 Columbian Exposition, and at one point seemed destined to supplant some subways, but never took root in cities for a variety of reasons. Vanderbilt turns to science fiction for inspiration, where 30 mph walkways put today's tortoise-like speed ranges of .5-.83 m/s to shame. In the meantime, Jerry Seinfeld will just have to learn to live with 'the people who get onto the moving walkway and just stand there. Like it's a ride.'"