I guess now that they'd have the escalator maintenence issues with steroids.
Imagine an old person or someone with movement issues not quite making the transition between the slower and high-speed bands. They’d end up as sort of human bowling ball, knocking down other passengers like skittles.
Similar thing happened to me on a crowded escalator at London Bridge tube station. Was about half way up when an old guy in front toppled back onto me. Thankfully I’d noticed he looked unsteady and managed to catch him under his armpits, otherwise we’d all have ended up in a heap at the bottom.
I didn’t have the leverage to get him upright, so we stayed with me holding him until we reached the top. His shoes hit the metal plate at the end and I flipped him to his feet.
We then gave each other a nod and went about our business.
Source: https://en.wikipedia.org/wiki/Moving_walkway#Trottoir_roulan...
Much like an escalator, really. People with mobility issues can't use them. Many people are afraid of them. They're hard to use safely with children and/or a pram.
I'm all for stairs for everyone who is able, and lifts for everyone who isn't.
Although, if we're making arguments about accessibility, I'm sure a more prosaic solution could be found that was no less accessible than just walking normally. But in any case, the usual approach is to have a scalable system for the 99% case, and then to provide an alternative that doesn't scale for the 1% who can't use the scalable solution - chairlifts etc.
Walls and roof protect you from excessive heat, excessive cold, wind, rain, snow, and the sound the mechanisms make.
Seats allow you (or people more tired than you) to sit and work, read, or rest, especially when you ride for an hour.
Also, train infrastructure is vastly narrower than such a collection of moving bands, and is readily available for maintenance when no trains are going.
The downside is that trains have to have stations. But the moving band will have to have a "station" all along it.
A belt system would run continuously, which means no waiting for the next train, and you don't have to slow down at every intermediate stop, which should improve average speeds.
Also, the amount of area and mass to move per passenger grows quite a lot, because most passengers will want to be on the fastest band, and all the gradual bands will be much less occupied.
The system can work reasonably when the moving bands are very lightweight, thin layers moved by a motor without many (or any) moving parts (the way maglev moves). It also should have absurdly low friction: unlike a train, it has a lot of contact surface.
To say nothing about turns.
Not that it's impossible, but technology-wise we're totally not there yet to make such a thing practical.
Add that to the "Places I don't want to be during a system failure."
How slow is it going to accommodate every single person's movement capacity? How small is the gradient between each belt to allow them to move between belts? How wide does this whole thing end up needing to be?
Why not? Don't they use moving floors on airports already? (Also, do toddlers walk alone on the busy streets?)
Here's a design I just sketched in Factorio for a belt system with 3 speed levels, and an entry/exit for moving onto the belt system, and then between speed levels.
(For those who don't know Factorio - the blue belts are the fastest, the yellow ones are the slowest.)
Yes, but they also have non-moving floors, and they also have -- in the US, at least -- a small fleet of carts, driven by airport staff, that can carry people who have difficulty walking.
Any moving-walkway mass-transit system would have to include accessible alternatives.
Being underground won't protect you from the noise of the mechanisms, but neither do the walls and roof of a train. Being on a train is loud.
Large crowds will cause heat within the system that will likely need to be managed, but -- like the noise -- this is equally true of trains.
How are any of those things an advantage of trains over a system of underground walkways?
In much of Europe that makes trains quiet, except metro trains with tight curve.
People excluded, I think non -metro trains are usually quieter than cars.
I've only used one train in the US, which ran on jointed (not welded) track so made the 'clickety clack' noise, but presumably that varies and the North East is better.
But okay, let's imagine out underground walkway. Since it's underground, you can't walk on and off where you want; you only walk off where there's way up to the ground. This eliminates much of the allure of the system. Now you want to plan ahead and be ready to get off when you're next to the exit. If you missed your exit, you have to move to the next exit, or maybe cross the tunnel and go to the band of the opposite direction, and walk back a bit.
Please notice how the low-speed bands then need to run the whole length of the tunnel, adding little to the carrying capacity: few people want to travel at the speed of walking when traveling at the speed of a train is a few meters across.
If we let only the faster band(s) through the length of the tunnel, and limit the slower bands to the exit areas (pretty long and wide), we'll face the problem of walls: our band is moving fast, and nothing separates it from the walls. So we sort of need inner walls on the band. But they need doors to allow people in and out in the exit areas. And the doors need to be shut when the band is in the tunnel. It starts to look like a... train? Only an endless train with a peculiar way of boarding.
This endless train also has a downside: if anything goes wrong, the whole band/train has to stop, it cannot be re-routed. What if we segment the band into individually routable parts? Only then they'll have to stop at exit areas to allow safe getting on / off them.
Well, we have reinvented the subway.
More recent trains can be quite protected from mechanism noises. The line I'm taking more often has received brand-new trains and I usually don't hear the noise.
it's kind of like a people mover, but has the ability to actually stop, thanks to the split/merge at the stops.
here's the general idea from a video game https://i.imgur.com/7gNHkNP.jpg
ideally multiple cars could pull out of the main track for loading and unloading(in which case you might have to wait a bit for the car in front).
Thirty years ago lots of people were talking about mass transit systems with small individual capsules. According to one of my engineering lecturers at the time, a limitation was that there simply isn't enough room on the ground to have all those capsules loading and unloading people in a CBD with lots of skyscrapers.
I have no doubt your lecturer is far more informed than i will ever be. I will assert that it's not really 1990 any more, and far more employers would be willing for employees to show up and leave at different times. Car congestion alone has made a lot of employers willing to have start time anywhere from 7 to 10. Which might alleviate some of that burden.
I also think, being able to take the whole trip without stopping - even if you occasionally have to go slower in high congestion areas - is much faster overall for each passenger. Which, in my humble opinion is a huge feature.
If the cars are reversible, you can also have Y junctions and stack up loads of cars perpendicular to the main rail, and fill those cars like a normal train.
https://www.thetransportpolitic.com/2009/05/21/paris-experim...