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Comment by Animats | Hacker News Reader

> People have tried faster moving walkways many times. The problem is getting humans on and off such a system safely in a way that is easy to maintain.

Right. You can build it, but not make it ADA-compliant. One subway station in France tried a 4km/h moving sidewalk, but the accident rate was too high.

The Paris system was really two trains on parallel tracks. Here's the mechanism.[1] Same concept as buses and trains where there are turntable sections between the cars. Powered by motors on the tracks. Possibly the first application of distributed power, with many motors pulling together in a controlled way.

Disney's PeopleMover, also powered by track motors and friction, can be thought of as a descendant. Disney had elaborate plans for little cars on tracks for EPCOT, but that never worked out.

[1] https://www.worldfairs.info/forum/viewtopic.php?f=10&t=125-l...

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The too-fast one in Paris was 12km/h, not 4km/h which would be OK.

https://en.wikipedia.org/wiki/Moving_walkway#Trottoir_roulan...

I took it many times, it didn't feel particularly dangerous but you had to pay more attention than on a regular moving walkway. What ultimately killed it was reliability, availability was too low. With more deployed I guess the kinks would have slowly disappeared, but the market just doesn't seem to be there.

Maybe because they began to iron out problems and saw the TCO rise too much.

Pearson airport in Toronto has ones that accelerate up to a fast speed. People who can’t use them can either walk beside them or hire a small electric golf cart. There is no reason to ban them just because a small portion of the population can’t use them.

Not sure but I think I read a while ago that they were removed due to unreliability (it's a while since I've been there myself).

It was very clever how they did the acceleration/deceleration - the "tiles" of the walkway fit together in such a way that each could slide on top of the next one, and at the two ends the tiles would gradually slide closer together (decelerating) or further apart (accelerating).

They were still there pretty recently when I was there. All escalators are a pain for maintenance though. Sure it's cheaper to force people to walk but that's not the point.

it is worth noting that we have transportation systems where you get into a slow moving vehicle that then speeds up. the cable car is a lot safer than a faster moving sidewalk because you can just get inside and sit down securely.

of course, it takes up a lot more space and costs a lot more money.

That's been tried. Never Stop Railway, 1924.[1] The drive system is a variable pitch screw between the rails. Large screw pitch between stations for fast travel, much tighter pitch in stations for very slow movement along the platform.

Never tried again with that kind of drive, although there are park rides where the loading platform moves. This requires safety devices and staff to prevent people jams at the end of the platform.

[1] https://www.youtube.com/watch?v=EX_MlWL7YKM

I'm talking about aerial cable cars, which are plenty in use around the world today. https://www.youtube.com/shorts/X5qjnryYWQY

They are pretty common tourist transports in mountainous areas and ski resorts. They're even being used for regular public transport now. https://www.youtube.com/watch?v=vdTE4TCqkZo

And you can only hop on/hop off a cable car at predetermined locations. To keep average speed high, those tend to be spaced relatively far apart.

I’m not sure about the “takes a lot more space”, and I definitely doubt about the “costs a lot more money”. Using outdoor escalators as proxies, I suspect outdoor moving sidewalks will need lots and lots of maintenance. If you want to have some guarantee of service you’ll also need multiple sidewalks side-by-side.

To be fair, on all moving walkways today you can only really get off at the beginning and the end.

That link is fantastic, thanks!

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