5 ms·

> Another fascinating thing is how escalators have two lanes, one for walking and one for standing. Why doesn't everyone so this?! It's so perfect! Turns out,

by dmoy 7y ago

> Another fascinating thing is how escalators have two lanes, one for walking and one for standing. Why doesn't everyone so this?! It's so perfect! Turns out, strangely, that it actually reduces throughput compared to just having everyone stand. So not exactly perfect I guess. But yea I agree in the general matter. When my MIL (a master organizer) visited Japan she thought that was great.

electriclove 7y ago
That's generally the custom in the US as well.
- davidmurdoch 7y ago
  Where in the US have you seen this? I've never seen it happen!
  - mistersquid 7y ago
    It's not strictly observed but in San Francisco BART people generally stand to the right while walkers pass on the left. EDIT: spelling
  - verylittlemeat 7y ago
    Super common in NYC. People will yell at you if you stand in the left lane on an escalator. First random video I googled for nyc escalator shows this behavior: https://www.youtube.com/watch?v=zmCOjC_9Iyc https://www.youtube.com/watch?v=zmCOjC_9Iyc
- htfu 7y ago
  Europe too. It'd surprise me if it isn't more common than not, globally.
dilap 7y ago
> Turns out, strangely, that it actually reduces throughput compared to just having everyone stand Wait, what? How can this be true? Imagine an escalator w/ both lanes filled with people just standing. Now imagine the left lane starts walking: clearly, higher throughput. Now, maybe you're imagining a scenario where people don't want to walk. Now everyone stands on the right, and the left lane is completely empty. OK, now we've reduced throughput by half compared to "everyone standing". So as we consider moving between the extremes of "no walkers" and "walker saturation", there will be some break-even point of throughput. And beyond that having a walking lane will be more efficient. (Also, besides raw throughput, having a walking lane gives you a better "fastest possible traversal time", which is also valuable, for people in a hurry.)
- dmoy 7y ago
  My first reaction to learning this was also about the same, haha. The issue with the "everyone starts walking" is the same reason why stationary cars are closer together than moving cars. If people walked with military trained precision you could get the same density and vastly higher throughput by walking. But for civilian strangers, it turns out two lanes of standing gives high enough density to trump the increased speed of walking, in terms of total throughput. I'm fairly certain there's even a study showing this. They tested it in london underground at least. But yes, it's certainly better for the few walkers.
  - dilap 7y ago
    Ah, I didn't consider density, that's a good point! Taking a look at the study you mention (linked in other comments), it seems like the escalators they studied were well to the "too few people want to walk" side of the curve to be efficient. I wonder how close the break-even point is to the simple metric, "do you have to wait to enter on the right?" Or thinking of the queue length for standers, clearly when the length is 0 allowing walking is more efficient (you've taken nothing away from the standers, and the walkers are more efficient). But there is some point where the stand-queue length, let's call it N, is big enough that the corresonding wait-time means overall throughput is lowered by allowing walking. I think it would be quite reasonable to require standing in those situations. So the rule could be something like, "stand on the right, walk on the left, unless there is a queue of more than N people waiting to stand on the right, in which case you may stand on the left." Easy right? ;-) (I wonder if N would vary w/ escalator length? Intuitively, almost certainly. So we'd have to post signs next to each escalator w/ its individual stand-queue limit. :-)
    - dmoy 7y ago
      That makes a lot of sense to me.
- mistersquid 7y ago
  > Now, maybe you're imagining a scenario where people don't want to walk. Agreed that this is an imagined scenario because people in a hurry will want to maximize their speed by walking/running up the escalator. More importantly, people generally (I'm imagining) do not want to stand on the same escalator step as another person, especially if they are strangers to each other. That means in a 2-lane standing escalator there will be breaks between people standing to the left or the right which, effectively, will turn a 2-lane standing-only escalator into a "1-lane" standing escalator.
davidmurdoch 7y ago
Even if it does reduce throughput, which from what I've seen comes in waves (after disembarking a train), the people who are okay standing there get to stand without being pushed, while those that are in a hurry get to hurry without pushing. Not everything has to be at max efficiency all the time, sometimes the optimal solution is relative.
unrealhoang 7y ago
I guess, that set up is optimized for latency and not throughput, which really makes sense.

by dmoy 7y ago

electriclove 7y ago

That's generally the custom in the US as well.

davidmurdoch 7y ago
Where in the US have you seen this? I've never seen it happen!
- mistersquid 7y ago
  It's not strictly observed but in San Francisco BART people generally stand to the right while walkers pass on the left. EDIT: spelling
- verylittlemeat 7y ago
  Super common in NYC. People will yell at you if you stand in the left lane on an escalator. First random video I googled for nyc escalator shows this behavior: https://www.youtube.com/watch?v=zmCOjC_9Iyc https://www.youtube.com/watch?v=zmCOjC_9Iyc
htfu 7y ago
Europe too. It'd surprise me if it isn't more common than not, globally.

dilap 7y ago

> Turns out, strangely, that it actually reduces throughput compared to just having everyone stand Wait, what? How can this be true? Imagine an escalator w/ both lanes filled with people just standing. Now imagine the left lane starts walking: clearly, higher throughput. Now, maybe you're imagining a scenario where people don't want to walk. Now everyone stands on the right, and the left lane is completely empty. OK, now we've reduced throughput by half compared to "everyone standing". So as we consider moving between the extremes of "no walkers" and "walker saturation", there will be some break-even point of throughput. And beyond that having a walking lane will be more efficient. (Also, besides raw throughput, having a walking lane gives you a better "fastest possible traversal time", which is also valuable, for people in a hurry.)

dmoy 7y ago
My first reaction to learning this was also about the same, haha. The issue with the "everyone starts walking" is the same reason why stationary cars are closer together than moving cars. If people walked with military trained precision you could get the same density and vastly higher throughput by walking. But for civilian strangers, it turns out two lanes of standing gives high enough density to trump the increased speed of walking, in terms of total throughput. I'm fairly certain there's even a study showing this. They tested it in london underground at least. But yes, it's certainly better for the few walkers.
- dilap 7y ago
  Ah, I didn't consider density, that's a good point! Taking a look at the study you mention (linked in other comments), it seems like the escalators they studied were well to the "too few people want to walk" side of the curve to be efficient. I wonder how close the break-even point is to the simple metric, "do you have to wait to enter on the right?" Or thinking of the queue length for standers, clearly when the length is 0 allowing walking is more efficient (you've taken nothing away from the standers, and the walkers are more efficient). But there is some point where the stand-queue length, let's call it N, is big enough that the corresonding wait-time means overall throughput is lowered by allowing walking. I think it would be quite reasonable to require standing in those situations. So the rule could be something like, "stand on the right, walk on the left, unless there is a queue of more than N people waiting to stand on the right, in which case you may stand on the left." Easy right? ;-) (I wonder if N would vary w/ escalator length? Intuitively, almost certainly. So we'd have to post signs next to each escalator w/ its individual stand-queue limit. :-)
  - dmoy 7y ago
    That makes a lot of sense to me.
mistersquid 7y ago
> Now, maybe you're imagining a scenario where people don't want to walk. Agreed that this is an imagined scenario because people in a hurry will want to maximize their speed by walking/running up the escalator. More importantly, people generally (I'm imagining) do not want to stand on the same escalator step as another person, especially if they are strangers to each other. That means in a 2-lane standing escalator there will be breaks between people standing to the left or the right which, effectively, will turn a 2-lane standing-only escalator into a "1-lane" standing escalator.

davidmurdoch 7y ago

Even if it does reduce throughput, which from what I've seen comes in waves (after disembarking a train), the people who are okay standing there get to stand without being pushed, while those that are in a hurry get to hurry without pushing. Not everything has to be at max efficiency all the time, sometimes the optimal solution is relative.

unrealhoang 7y ago

I guess, that set up is optimized for latency and not throughput, which really makes sense.