3 ms·

We have available to us high-speed, high-capacity elevators now, standard in large buildings. The DC Metro's escalators were a lot of things, among them great

by mapt 11y ago

We have available to us high-speed, high-capacity elevators now, standard in large buildings. The DC Metro's escalators were a lot of things, among them great big monumental architectural Statements; But as you and anyone else from the area knows, they were not particularly well thought-out (and we are still paying for that mistake in maintenance problems, wait times, expensive rain shelters, et cetera). Their progenitor, as I recall, went to the great lengths of riding them aboard a wheelchair every day in a pained attempt to prove to the planning committee that elevators, which would have spoiled his precious vaulted look, were not necessary.

dredmorbius 11y ago
Elevators and the numbers of bodies you need to move with mass transit really aren't amenable. A ten-car train in an urban commuter rail system might have 40-80 passengers per car. That's up to 800 people deboarding (say, for a downtown terminal station), though generally you're looking at a low few hundred. Dumping that demand onto 3-4 escalators is doable, and the streaming is continuous. For elevators, I don't see it working. Too many people and elevators don't operate continuously as escalators do. Unless there've been tremendous advances I'm unaware of. Schindler's high-capacity elevators are rated for 6-21 people. It would take 38 elevator trips to empty the train I described above (divide among multiple shafts and/or car trips as you like, but realize that speed is 1-1.6 m/s (about 3.6 mph), or just over 60s to travel 100m, plus return and dwell time. If train service intervals were ten minutes, you'd need ten shafts assuming 3 minutes per round-trip to clear 800 passengers. http://www.schindler.com/content/pl/Internet/pl/modernizacja/_jcr_content/rightPar/downloadlist/downloadList/80_1351088438162.download.asset.80_1351088438162/SCHINDLER%205400%20(eng).pdf http://www.schindler.com/content/pl/Internet/pl/modernizacja...
- kazinator 11y ago
  > [E]levators don't operate continuously as escalators do. [...] Unless there've been tremendous advances I'm unaware of. http://en.wikipedia.org/wiki/Paternoster http://en.wikipedia.org/wiki/Paternoster :)
  - GFischer 11y ago
    Very interesting... if Hitachi did go past the prototype stage, it could indeed be the answer... Video from the link (in Japanese): https://www.youtube.com/watch?v=j7YIBWve0n4 https://www.youtube.com/watch?v=j7YIBWve0n4
    - jacquesm 11y ago
      Paternosters have been used in the past but usually were discontinued because of (gruesome) accidents. There were a couple in Amsterdam in my childhood.
      - GFischer 11y ago
        Yes, the old versions (where there were periods in which someone could fall into a shaft) look dangerous. The Hitachi version is interesting because it incorporates the behaviour one expects from standard elevators, at the cost of some speed. It sounds ideal for a mass transit station, and it could use the same pattern as is currently used for subways (a small time it remains motionless, then the doors close after a beep). I found an English version of their video https://www.youtube.com/watch?v=mnX5WZhvzZY https://www.youtube.com/watch?v=mnX5WZhvzZY and ThysenKrupp is also working on a similar idea: http://rt.com/news/210143-maglev-horizontal-elevator-thyssenkrupp/ http://rt.com/news/210143-maglev-horizontal-elevator-thyssen... Though Hitachi has decided to focus on speed instead: http://www.smithsonianmag.com/ist/?next=/smart-news/worlds-fastest-elevator-will-be-built-china-180951203/ http://www.smithsonianmag.com/ist/?next=/smart-news/worlds-f... I hope the innovation in this space doesn't dry out :)
        dredmorbius 11y ago
        Falling into shafts is bad. Getting stuck between car and floor strikes me as rather worse. I'm familiar with a few such incidents (friends were witnesses, I, fortunately, was not), with conventional elevators, overloaded. The screaming, and then lack, is apparently something not easily forgotten.
  - dredmorbius 11y ago
- mapt 11y ago
  The Wheaton DC Metro station features the longest set of single-span escalators in the Western Hemisphere, each featuring a length of 230 feet (70 m), with a vertical rise of 115 feet (35 m). The trip takes approximately 2 minutes and 45 seconds. Extrapolate that to a ~100m depth for a wait of 8 minutes 15 seconds, with a ~200m horizontal span that needs to be excavated manually all the way to the surface - you probably need one to two city blocks of demolition for a 30deg escalator. There are some high-speed elevators out there, at these heights we're strongly limited by comfortable acceleration (at the highest peak speeds from Mitsubishi or Toshiba you'd be talking about upwards of ~15m/s, but you couldn't safely reach those at this height). 1m/s^2 seems to be okay. That puts a half a trip at 10 seconds, or 20 seconds from when the doors finish closing to when the doors begin opening. Figure 25 seconds on either end for filling and emptying, and you have a 90 second round trip. Expect something like 4 20-person elevators for typical stops, to maybe 16 for an inner-city transfer station, and you can move 50-200 people per minute. According to Metro, a single escalator can move 90 people per minute; They typically pack 2 escalators and a stairwell, or 3 escalators running 2-1 peak flow, into a shaft, but escalator availability ran as low as 60 percent for a number of decades before a recent improvement drive (now ~92%), so you had good odds that at least one was broken (or, in optimistic parlance, 'had become stairs').

by mapt 11y ago

dredmorbius 11y ago

Elevators and the numbers of bodies you need to move with mass transit really aren't amenable. A ten-car train in an urban commuter rail system might have 40-80 passengers per car. That's up to 800 people deboarding (say, for a downtown terminal station), though generally you're looking at a low few hundred. Dumping that demand onto 3-4 escalators is doable, and the streaming is continuous. For elevators, I don't see it working. Too many people and elevators don't operate continuously as escalators do. Unless there've been tremendous advances I'm unaware of. Schindler's high-capacity elevators are rated for 6-21 people. It would take 38 elevator trips to empty the train I described above (divide among multiple shafts and/or car trips as you like, but realize that speed is 1-1.6 m/s (about 3.6 mph), or just over 60s to travel 100m, plus return and dwell time. If train service intervals were ten minutes, you'd need ten shafts assuming 3 minutes per round-trip to clear 800 passengers. http://www.schindler.com/content/pl/Internet/pl/modernizacja/_jcr_content/rightPar/downloadlist/downloadList/80_1351088438162.download.asset.80_1351088438162/SCHINDLER%205400%20(eng).pdf http://www.schindler.com/content/pl/Internet/pl/modernizacja...

kazinator 11y ago
> [E]levators don't operate continuously as escalators do. [...] Unless there've been tremendous advances I'm unaware of. http://en.wikipedia.org/wiki/Paternoster http://en.wikipedia.org/wiki/Paternoster :)
- GFischer 11y ago
  Very interesting... if Hitachi did go past the prototype stage, it could indeed be the answer... Video from the link (in Japanese): https://www.youtube.com/watch?v=j7YIBWve0n4 https://www.youtube.com/watch?v=j7YIBWve0n4
  - jacquesm 11y ago
    Paternosters have been used in the past but usually were discontinued because of (gruesome) accidents. There were a couple in Amsterdam in my childhood.
    - GFischer 11y ago
      Yes, the old versions (where there were periods in which someone could fall into a shaft) look dangerous. The Hitachi version is interesting because it incorporates the behaviour one expects from standard elevators, at the cost of some speed. It sounds ideal for a mass transit station, and it could use the same pattern as is currently used for subways (a small time it remains motionless, then the doors close after a beep). I found an English version of their video https://www.youtube.com/watch?v=mnX5WZhvzZY https://www.youtube.com/watch?v=mnX5WZhvzZY and ThysenKrupp is also working on a similar idea: http://rt.com/news/210143-maglev-horizontal-elevator-thyssenkrupp/ http://rt.com/news/210143-maglev-horizontal-elevator-thyssen... Though Hitachi has decided to focus on speed instead: http://www.smithsonianmag.com/ist/?next=/smart-news/worlds-fastest-elevator-will-be-built-china-180951203/ http://www.smithsonianmag.com/ist/?next=/smart-news/worlds-f... I hope the innovation in this space doesn't dry out :)
      - dredmorbius 11y ago
        Falling into shafts is bad. Getting stuck between car and floor strikes me as rather worse. I'm familiar with a few such incidents (friends were witnesses, I, fortunately, was not), with conventional elevators, overloaded. The screaming, and then lack, is apparently something not easily forgotten.
- dredmorbius 11y ago
mapt 11y ago
The Wheaton DC Metro station features the longest set of single-span escalators in the Western Hemisphere, each featuring a length of 230 feet (70 m), with a vertical rise of 115 feet (35 m). The trip takes approximately 2 minutes and 45 seconds. Extrapolate that to a ~100m depth for a wait of 8 minutes 15 seconds, with a ~200m horizontal span that needs to be excavated manually all the way to the surface - you probably need one to two city blocks of demolition for a 30deg escalator. There are some high-speed elevators out there, at these heights we're strongly limited by comfortable acceleration (at the highest peak speeds from Mitsubishi or Toshiba you'd be talking about upwards of ~15m/s, but you couldn't safely reach those at this height). 1m/s^2 seems to be okay. That puts a half a trip at 10 seconds, or 20 seconds from when the doors finish closing to when the doors begin opening. Figure 25 seconds on either end for filling and emptying, and you have a 90 second round trip. Expect something like 4 20-person elevators for typical stops, to maybe 16 for an inner-city transfer station, and you can move 50-200 people per minute. According to Metro, a single escalator can move 90 people per minute; They typically pack 2 escalators and a stairwell, or 3 escalators running 2-1 peak flow, into a shaft, but escalator availability ran as low as 60 percent for a number of decades before a recent improvement drive (now ~92%), so you had good odds that at least one was broken (or, in optimistic parlance, 'had become stairs').