In this project, " Nimble Cities," Slate wants to hear your best ideas for making urban transportation more efficient, safe, and pleasant. Read Tom Vanderbilt's explanation of Nimble Cities. You can scan all the proposals submitted by readers so far here and vote for your favorites. Tom Vanderbilt will evaluate the most interesting ideas and the top vote-getters.
While the last two Nimble Cities ideas I've written about—reforming parking codes and creating bicycle highways—have been fairly sober and down to earth, that's not to say there's not room for the dreamers, and I couldn't help but notice among the proposals several that included some form of urban moving walkway. One reader called for an "electrorheological (ER) 'smart fluid' to create flexible moving walkways" while another suggested tapping into the power of "crazy circular motion" to move people around. (He proposed building a series of concentric moving walkways.) "The station itself is a fixed hub. From where you stand you can see many concentric circles of moving walkway stretching into the distance. The one nearest you is moving at .5 miles per hour. You step onto it. Boom. The next is moving at 1 mile per hour. You step onto it. Boom." And so on.
If it sounds like the stuff of science fiction … well, it has been. In his short story "The Roads Must Roll," Robert Heinlein imagined the United States—facing a war-strained petroleum shortage that meant the "end of the automobile era was in sight"—shifting to a series of massive commuter moving walkways. Of the first "mechanized road," built between Cincinnati and Cleveland, Heinlein writes: "It was, as one would expect, comparatively primitive in design, being based on the ore belt conveyors of ten years earlier. The fastest strip moved only thirty miles per hour, and was quite narrow, for no one had thought of the possibility of locating retail trade on the strips themselves."
The moving walkway, of course, is a firmly entrenched and familiar transportation technology, but it has been largely limited to controlled (and typically transportation-related) environments, like airports, train stations, or theme parks. Its history unspools further back than you might imagine. As Paul Collins has written, the first moving sidewalks were unveiled at Chicago's 1893 Columbian Exposition (where they could shuttle 31,680 passengers per hour), again at the 1900 Paris Exhibition, and seemed well on their way to conquering cities like New York. As Collins writes, Max Schmidt, the creator of the Chicago walkway, "proposed a flurry of similar projects around Manhattan—running down Broadway, along Wall Street, over the Williamsburg Bridge and across 23rd and 34th Street. To Schmidt, the advantages of the moving walkway were so compelling that he was convinced they would supplant some subways rather than supplement them. By 1909, he was pushing a massive $70 million scheme that would provide Manhattan with a network of subterranean moving sidewalks."
For a variety of reasons—maintenance concerns (think of how many escalators you've seen out of service), weather issues, and perhaps even that very competition with the subways—the moving walkways never took root in cities. After a half-century's slumber they began to appear (under brand names like "Travelator" or "Speedwalk") in places ranging from train stations to Disney's Space Mountain, and even in cities like Tokyo (home to the Yebisu "Skywalk") and Hong Kong, where one can find not only the world's largest covered outdoor escalator, but three outdoor (and inclined) moving walkways.