8 ms·
The big benefit is that you get more than one elevator per shaft. For skyscrapers the amount of floor space wasted by elevators grows exponentially by the numbe
by danielvf 9y ago
The big benefit is that you get more than one elevator per shaft. For skyscrapers the amount of floor space wasted by elevators grows exponentially by the number of floors.
Say you have a 5 story building that needs a one shaft elevator. 5 floors tiles 100 sqft per floor is 500 sqft of wasted shaft space. Then say you have a 10 story building that needs two shafts. Now you are wasting 10 floors times two shafts or 2,000 sqft. And so on.
An old and terrifing solution to this was to use two shafts and run a continuous loop of open door elevators.
https://m.youtube.com/watch?v=Ro3Fc_yG3p0 https://m.youtube.com/watch?v=Ro3Fc_yG3p0
- anoother 9y agoPaternosters. You say terrifying, I say fun. There's one in Leicester University (not the only one in the UK, I'm sure). Really not that dangerous, with a cable near the top of each aperture that triggers a stop if it's touched.
- stcredzero 9y agoThe SF garage my fiancee parks in has this thing made from an industrial belt, with steps bolted onto it. I think there are quite a few of those in Stuttgart as well, though they are being fazed out. It's very efficient, but not for ze stupits!
- pimlottc 9y agoOut of curiosity, where in SF? I'd be interested to see one.
- stcredzero 9y agoThe parking garage near the corner of Bush and Mason.
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- URSpider94 9y agoI saw one like this as a child, in Chicago. As I remember, it was explicitly only for the employees to use to get to the cars, as it was a valet facility.
- stcredzero 9y agoThat's what the one I saw was!
- christoph 9y agoThere's one in the library at Essex University as well - https://www.youtube.com/watch?v=pvn06yQIb9o https://www.youtube.com/watch?v=pvn06yQIb9o I'm glad they still have it, I was nervous when I searched that I would find out it had been ripped out since I was last there.
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- itcrowd 9y agoThis is right if you assume constant floor area for increasingly taller buildings. I think taller buildings require more floor space and that offsets the increase (at least somewhat).
- spookyuser 9y agohttps://www.youtube.com/watch?v=YgJBD1wf-YQ https://www.youtube.com/watch?v=YgJBD1wf-YQ Here is Tom Scott's video about the continuous loop elevator's.
- lathiat 9y agoBetter video :-)
- mindleyhilner 9y agoSorry to sound stupid, but how is that exponential? Isn't it O(mn) where m = number of floors and n = number of shafts? EDIT: Unless there's some dependence between m and n, like if taller buildings always need more shafts or something.
- JumpCrisscross 9y ago> like if taller buildings always need more shafts or something The dependence is on keeping wait times reasonable. Taller buildings mean each shaft's elevator spends more time travelling, i.e. less time being available.
- masklinn 9y agoAt this point you start doing locals (multiple elevators per shaft traversing only a subset of the entire building) and express (elevators skipping floors, usually between ground floors and various "sky lobbies" at 30~40 floors interval).
- JumpCrisscross 9y agoWhich still involves adding shafts.
- ajarmst 9y agoThere's also a weight issue. The longer the shaft, the longer and heavier the cable must be, and the more tension and stretch. In some buildings, there may also be structural issues militating against an open shaft running the entire heightof the buldng.
- rtkwe 9y agoTaller buildings need more shafts because they'll spend more time in transit so unless the occupants have the patience of saints you need lots shafts to keep wait times down. Eventually most tall buildings setup sky lobbies and express lifts that only service a certain range of floors to keep wait times down during peak hours. It's really rough in convention center hotels when a huge convention comes to town a lot of the time it's practically impossible to get an elevator down from the middle floors because it's already full from the floors above you.
- beefman 9y agoThat's polynomial growth http://www.wolframalpha.com/input/?i=100+*+f+*+ceil(f%2F10) http://www.wolframalpha.com/input/?i=100+*+f+*+ceil(f%2F10)
- danielvf 9y agoI deserved that. My examples understate the real life problem though. This missing factor is that it also costs more shaft time to serve a higher floor with a longer travel distance than it does a lower floor with a shorter travel distance. So in the simple elevator case, people from floor one hundred are going to be spending more time in the shaft than people from floor ten. Still not exponential, but cubic-ish growth puts a hard limit on things.
- mjevans 9y agoRight, that also explains the concepts of 'express' elevators and lobby floors. Due to the passengers the rate of travel for an elevator is not constant: * There's a maximum rate of acceleration and deceleration that people are comfortable with. * A longer travel distance means more time to speed up / slow down. * Thus an elevator or two which are dedicated to operate at the longer distance travel that distance at a more effective speed and provide more rapid service. * Even more importantly, it also cuts down on the number of slow elevator shafts necessary to service floors by allowing them to be stacked.
- lobster_johnson 9y agoThe space isn't wasted if it's used to transport people, though.
- BurningFrog 9y agoIn an n floor building, nobody is being transported in n-1 floors.
- lobster_johnson 9y agoNo one is using 100% of the space in the rest of the building either. Restrooms aren't a waste of space even if they're not constantly filled. Not everything has to be at 100% utilization to be worth the investment.
- wlesieutre 9y agoBut as you make a building larger the number of restrooms increases linearly. A building twice the size uses twice the space for restrooms. Say you design a 50 story building and it has one bank of elevators that all run from 1 to 50. What if you wanted to make it twice as high, and have the same elevator capacity for the top half? You can add another identically sized bank that starts at the ground floor, skips up to 51 and then covers from there to 100. In the top half of the building you used the same fraction of space for your elevator shafts as you'd used originally. Great! Except the elevator shafts to get there had to go through floors 2-50, and they ate up as much space there as the original elevator bank did. The building has 2x the original volume, but you're spending 3x the space on elevator shafts so you didnt double the useful floor area. As you try to design taller and taller buildings, the increasing cost of vertical circulation gets worse and worse.
- Dylan16807 9y agoThat's not a counter. No matter what your goal utilization is, your ability to deliver that per square foot drops tremendously. If restrooms were like elevators then adding a bunch more floors would suddenly require all two-stall restrooms in the building to be five times as big.
- smoyer 9y agoI rode one of those "terrifying" elevators in the '90s in Frankfurt DE and it wasn't actually scary. I could in fact be dangerous but people are pretty smart about not being stupid near them. I will admit that we taped a piece of paper to the floor to make sure the cabin (which was completely carpeted) didn't flip over at the top before we rode it the whole way around.
- e12e 9y agoCould you expand on your "safety paper"? Was it taped to the top floor, as a signal to get out?
- mjmasn 9y agoTook me a while to parse but I think he means they taped paper to the floor, then observed that the paper was still on the floor (as opposed to the ceiling) after the elevator looped around. The entire elevator was carpeted so it wasn't obvious if this would be the case or if indeed the elevator flipped over before beginning its descent.
- mkl 9y agoNot OP, but here's how I think it worked: There are effectively two vertical shafts, and the elevator car goes up one and down the other. If the car flipped over as it goes over the top to the other shaft, then what was the floor would become the ceiling. So, tape something to the floor to identify it as it's going up, then wait for that car to come down the other shaft and look at where your identifying paper is. It does seem pretty obvious that it wouldn't flip over - that seems like an insanely dangerous design.
- e12e 9y agoAh, yeah I guess that makes sense :-)
- smoyer 9y agoNo ... since the elevator compartments were completely carpet covered, we wanted to make sure they didn't flip over when then went around the top and bottom (and yes it was taped to the floor).
- DenisM 9y agoPerhaps you could just hang two elevators on one set of cables in the same shaft? They will have to move in sync and the range will be cut in half, but the throughput will nearly double during the rush hour. In a tall building could be an acceptable tradeoff.
- jdavis703 9y agoThat makes it a lot harder to have a dramatic lobby, which is an important component of most skyscrapers.
- wlesieutre 9y agohttps://en.wikipedia.org/wiki/Double-deck_elevator https://en.wikipedia.org/wiki/Double-deck_elevator is like that, but right on top of each other so the range isn't reduced. Most people are going between the ground floor and whatever floor their destination is on, so a shaft with two cars that go 0-50 and 51-100 wouldn't be very useful.
- DenisM 9y agoIndeed. Same article also covers shared-shaft elevators, exactly as I described.
- wlesieutre 9y agoAh, sky lobbies are a neat solution to get more efficient use out of the two elevators, I've never encountered one of those!
- willyt 9y agoActually it's quite common to have cars in the same 'shaft' serving a subset of floors. The original world trade centre towers pioneered this system. Express elevators take you to transfer lobbies and then you transfer to local elevators for intermediate floors. The locals for different sets of levels occupy the same footprint within the building.
- 35bge57dtjku 9y agoWhy not invent and install spiral escalators? That would give you the high throughput of the paternoster more safely. You could still have a few elevators for travel between the higher up 'elevator lobbies' people mentioned.
- kurthr 9y agoWow, cool... they have! http://gizmodo.com/feast-your-eyes-on-the-worlds-largest-spiral-escalator-1691920542 http://gizmodo.com/feast-your-eyes-on-the-worlds-largest-spi... There must be more spiral escalators now. I know there's one in Nordstrom's too.
- 35bge57dtjku 9y agoNice. I was picturing one more like a spiral staircase though, where the inner edge of each step touches an inner pole.