[mherdeg]

Heinlein's "The Roads Must Roll" posits a network of very fast, very long moving walkways which could be used for mass transit (you'd ramp up speed on slower ones then hop over to a fast one). Wikipedia says that moving walkways had been in sf for decades by that point, but Heinlein also almost incidentally invents the Segway in the story -- just a little treat.

I love peoplemovers (like the Hong Kong Central-Mid Level escalators and the delightfully bouncy SFO walkways) and always wondered what would have to be different for us to get super-fast ones for transit.

In Boston, IMO they would be at least as good as the Green Line :)

[mpsprd]

Asimov introduced me to this concept in I robot.

In his version there were multiple levels of speed for entry/exit of transit so the main highways were going really fast.

IIRC it required some dexterity to use and sounded a bit dangerous...

[adolph]

Requires dexterity and seems somewhat dangerous? Meet the Paternoster elevator:

https://en.wikipedia.org/wiki/Paternoster_lift

[user982]

Are you sure it wasn't The Caves of Steel?

[bee_rider]

As long as there aren’t any gaps, I guess it is just the difference in the belt speeds that you care about. Also the wind.

[corlinpalmer]

Moving walkways have a big power efficiency problem over a distance. While you can make a train track longer without decreasing the efficiency of the train, a moving walkway has to move that whole walkway. Can you imagine the friction on a 10 mile long moving walkway? You would need massive motors just to budge it.

[ricardobeat]

If, like in the design seen here, the slide movement and propulsion is decoupled, and motors add impulse to the platforms at constant intervals, doesn't sound like that would be a problem. These wood platforms must have weighed tons by the way.

[anothernewdude]

Doesn't need to be one big continuous walkway.

[thereisnospork]

Required power should essentially be a constant per unit length, can easily have 1 motor per kilometer or city-block.

And for my dumb idea of the day: 'just' use solar panels as the walking surface as use that to power the slidewalk.

[cpill]

could hoover like a monorail?

[twelvechairs]

Mid level escalators have a very definite purpose as people wouldn't walk up that steep slope before.

Moving walkways along flat surfaces though? Its very hard to make them attractive. Most people like to walk a little, certainly we are built for it genetically and most people don't walk as much as they should in any case. In terms of mass transit nobody has ever got the safety and space issues to work. They only really have tended to work in airports where there are sometimes very large distances to traverse, and you need an (actually pretty slow moving for safety) solution for the elderly etc. who aren't as mobile. Even at an airport unless distances are massive and people have giant luggage most will prefer to walk, or only take the moving walkway for novelty value.

[iainmerrick]

In airports I’ve been to, most people walk on the moving walkways. Twice as fast!

[soperj]

People would walk more if they could get to where they were going fast. If you could walk to the store as quickly as you could drive, why would you get in the car? No traffic jams on a sidewalk.

[strken]

I'd never heard of the mid-level escalators before. Apparently they're on a slope with an elevation gain of 135m over 800m, which is pretty serious for someone who's out to do some shopping: https://en.m.wikipedia.org/wiki/Central%E2%80%93Mid-Levels_e...

[Andrex]

Getting out and walking was frequently as good as the Green Line when I lived there...

[occams_chainsaw]

Same for me just in October for some stretches

[euroderf]

In Heinlein's books, do the rolling roads come before or after the establishment of American theocracy ?

Asking for a friend.

[dsq]

Just from my rusty memory, the roads were after the Crazy Years and before the Prophet. So yes, before the theocracy. EDIT: I found a link to the chart.

http://templetongate.net/graphics/literature/fhchartlarge.gi...

[riffraff]

I seem to recall this is also a thing in "the city and the stars" by Clarke (1956), including the fact that it's faster towards the middle. I imagined a river of asphalt and it was kinda cool.

[mauvehaus]

> In Boston, IMO they would be at least as good as the Green Line :)

Yeah, but the E line down South Huntington would be downright perilous :-D