[HN Gopher] Where to wait for an elevator (2010)
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Where to wait for an elevator (2010)
 
Author : bumbledraven
Score  : 66 points
Date   : 2022-07-06 17:07 UTC (5 hours ago)
 
web link (www.johndcook.com)
w3m dump (www.johndcook.com)
 
| baxtr wrote:
| Might be a bit off-topic...
| 
| But: The one big question I have with elevator UX is this: why
| isn't it possible to deselect a choice? So pressed 10th floor but
| wanted 11th. There is no way to press button 10 and then button
| 11 to correct that mistake.
| 
| Will I ever solve this mystery?
 
  | thefifthsetpin wrote:
  | Some elevators are clever enough to detect kids messing with
  | them. If you select enough floors, they'll just deselect
  | everything soon, including your errant selection.
  | 
  | Admittedly, that's not very helpful unless you somehow knew
  | that the elevator you were in had been configured in such a
  | way.
 
  | rootusrootus wrote:
  | I imagine that's by design. Otherwise you could unselect other
  | people's choices.
 
    | baxtr wrote:
    | Yes of course it's by design. I just wonder why.
 
      | samatman wrote:
      | Maybe ask a woman?
 
      | dejj wrote:
      | In Marc-Uwe Kling's "Qualityland", reversing elevators,
      | turning around subway cars, and flicking traffic lights is
      | a level-skill obtained by accumulating social credit
      | points.
      | 
      | [1] https://www.amazon.com/Qualityland-Visit-Tomorrow-Marc-
      | Uwe-K...
 
      | mulmen wrote:
      | Because you could deselect other peoples choices.
 
        | eddd-ddde wrote:
        | This isn't an argument, as you can also select other
        | people's non-choices.
 
        | [deleted]
 
        | halfnormalform wrote:
        | Elevators sometimes have an anti-mischief feature where
        | they will deselect every floor if all the floors are
        | selected in a brief period of time. The cab will slow to
        | a stop if no new buttons are pressed. It's kind of eerie,
        | actually.
 
        | mulmen wrote:
        | Neat! How do you know this?
 
        | halfnormalform wrote:
        | The elevators at my office were upgraded a few years ago
        | and one of the elevator techs happened to mention it to
        | me. I tried it out while alone, for obvious reasons.
 
        | mulmen wrote:
        | Cool. I was hoping for something other than "I
        | exhaustively test all new elevators".
 
        | rootusrootus wrote:
        | There's some incentive not to do that, however, because
        | in many cases it will inconvenience you just as much as
        | everyone else. But if you could just deselect all the
        | floors between the current one and your destination,
        | there's a pretty strong incentive there.
        | 
        | Until someone punches you out, of course, because it'd be
        | hard to hide and you're in a confined space with them...
 
        | rahimnathwani wrote:
        | That doesn't prevent people from getting to their
        | destination.
 
        | ehvatum wrote:
        | How do I go about deselecting other people's choices, if
        | that's my specific goal? I can get whatever I want in
        | Jira, but nothing in elevators. It's fucked.
 
        | [deleted]
 
      | jaywalk wrote:
      | Not worth complicating the UX to address such a minor
      | issue.
 
        | baxtr wrote:
        | Minor to you... Introducing a great experience is the job
        | of good UX. Not simply limiting options and saying
        | 'done'. I am sure there are better options to handle
        | this. Seems like no-one has put the effort into it (yet).
 
        | [deleted]
 
        | jaywalk wrote:
        | Unnecessarily stopping at a floor for a few seconds is
        | minor to literally everyone riding in a public elevator.
        | 
        | But yeah, I'm sure that at all of the various elevator
        | companies, over all of the years that elevators have had
        | electronic controls, nobody has bothered to put any
        | thought into this.
 
        | allenu wrote:
        | This is it exactly. It opens up the door to even more
        | complexity in the design...
        | 
        | Now that you can unselect floors, if the elevator is on
        | its way to the 5th floor and you unselect it, should it
        | skip that floor mid-movement?
        | 
        | If there's only one floor selected, we'll probably want
        | to disallow unselecting it while the elevator is moving,
        | but what if you just hopped on and it hasn't moved yet?
        | 
        | This would probably make for an interesting interview
        | question.
 
  | asmosoinio wrote:
  | In the Philippines (tested in Manila) high rises this seemed to
  | be a common feature: Double clicking a selected floor would
  | deselect.
 
  | NovemberWhiskey wrote:
  | Elevators in Japan often support this; usually either a double-
  | tap or press-and-hold the button to deselect.
 
  | butterNaN wrote:
  | I have been to a few elevators in India where you can deselect
  | a choice like you described. However they are not rare.
 
  | layer8 wrote:
  | There are two cases where deselecting a floor would complicate
  | the logic:
  | 
  | 1. When the currently targeted floor is deselected and the
  | remaining selected floors are all in the other direction: Then
  | the elevator would have to either reverse course without
  | stopping -- a situation which otherwise doesn't occur and would
  | be unexpected and possibly dangerous for the passengers -- or
  | stop on a non-selected floor before changing direction, which
  | would be confusing as well.
  | 
  | 2. The deselected floor was the only selected floor: The
  | elevator would then have to choose a floor to stop on by itself
  | -- e.g. the next one it can safely stop on -- which is also a
  | situation that doesn't otherwise occur. In addition,
  | deselecting the only selected floor doesn't seem to be a
  | practical use case.
  | 
  | So instead of having to define, implement and test a behavior
  | for those odd situations, it's safer and less costly to just
  | disallow deselection.
 
    | xmodem wrote:
    | Rather than testing these scenarios, couldn't one simply
    | just(tm) not allow deselection in these scenarios?
 
      | layer8 wrote:
      | Then you'd have to test _that_. And it would still be
      | confusing to users that deselecting only sometimes works.
 
        | bobthepanda wrote:
        | Right.
        | 
        | HN is not representative of the average person, or even a
        | standard cross section of society. A elevator has to be
        | legible to an 8 year old child, an 80 year old retiree,
        | someone who is blind, a person who is deaf, etc.
        | 
        | When designing for such a broad audience, KISS (keep it
        | simple, stupid)
 
    | deathanatos wrote:
    | I didn't think elevators permitted scenario 1 to occur at
    | all; I thought they refused to allow selecting floors not in
    | the direction of travel.
    | 
    | (I don't usually board elevators traveling in the wrong
    | direction, ofc., so, I'm not that sure.)
 
      | zerocrates wrote:
      | I haven't done it in a while but my recollection is that if
      | you press a "wrong-direction" floor it will just go there
      | after having completed all the previously-selected stops.
 
        | scrumbledober wrote:
        | not just previously selected but it will wait until there
        | are no stops in the current direction, then switch
        | directions and go in the reverse order
 
        | zerocrates wrote:
        | Yeah I wasn't sure what will happen if more people add in
        | stops in the "right" direction afterwards, I don't think
        | I've ever been in that situation, but that makes sense.
 
      | spogbiper wrote:
      | The one in my building will allow you to select any floor
      | at any time. it always goes to the last stop in the current
      | direction before reversing as far as i have noticed
 
    | [deleted]
 
  | hahnchen wrote:
  | If I were to guess, people enter the elevator and
  | subconsciously just press which floor they want to go to. If
  | you allow deselecting, someone will inadvertently deselect
  | where they want to go to if that button is already selected.
 
  | pflenker wrote:
  | Because in a busy environment (where consistently more than one
  | person uses the elevator) the scenario of making a wrong
  | decision and having the wish to correct it occurs far less than
  | the scenario where someone does not pay attention to which
  | floors have been selected already and deselects your
  | destination. At the worst case this means that you both miss
  | your stop because you both did not notice.
 
    | baxtr wrote:
    | Yes, some elevator environments are busy. But many aren't.
 
    | alephxyz wrote:
    | Might also get confusing if the LED indicating the button's
    | been pressed stops working
 
      | Swenrekcah wrote:
      | This comment right here is an example of thinking like a
      | good designer. No amount of sleek surfaces and cool
      | lighting can beat this.
 
        | h4waii wrote:
        | Leave the button recessed after it's been selected, even
        | if the LED fails (how often does this actually happen?)
        | it's still a visual and tactile indicator.
        | 
        | To deselect the floor, simply press in again.
 
| mellavora wrote:
| So why is it that if you select 2 and 3 you don't get to floor 5?
 
  | vidanay wrote:
  | You mean 6?
 
    | mikkergp wrote:
    | I mean 8
 
| OisinMoran wrote:
| "Since you can't move without increasing the average distance,
| you must have started at the best spot."
| 
| Technically this isn't a fully sound inference. All this proves
| is that you're at a _local_ optimum. So you 'd also need to know
| or show that there is only one optimum/the problem is
| convex/local=global or any variant.
| 
| Of course that _is_ the case here, but it 's always worth noting
| the specific properties of a problem that make a neat solution
| possible.
 
| glitcher wrote:
| The best real-world optimization: stand aside to make room for
| anyone exiting the elevator before crowding the doorway trying to
| walk in too quickly!
 
  | novosel wrote:
  | Oh my god, this.
 
| acomjean wrote:
| clearly they aren't using "destination dispatch" where the
| elevator tells you where to wait after you tell it where you want
| to go.
| 
| https://en.wikipedia.org/wiki/Destination_dispatch
| 
| I've only seen this in one building. It was a little weird, but
| it supposedly is coming soon to more and more elevators.
 
  | tarentel wrote:
  | I worked in a building at NYC that did this. It was confusing
  | at first as I just immediately jumped into the first elevator
  | door that opened since it was my first day and didn't realize
  | there were no buttons inside. After the initial and very short
  | learning curve due to all the stairs I had to climb that day I
  | would say it was much more efficient than any other building I
  | had been in.
 
    | bombcar wrote:
    | I encountered one that did this, but the screen for selecting
    | your floor was a temperamental touch screen, so trying to
    | type "13" would often select "1" and "11" before 13,
    | consigning you to riding and stopping at those floors, also.
    | 
    | Then I found the secret wheel-chair button assortment, which
    | was genuine buttons.
 
  | yccs27 wrote:
  | If you want a fun challenge, try making your own elevator
  | algorithm! https://play.elevatorsaga.com/
 
  | jaywalk wrote:
  | I stayed at a hotel that used this. It's a very nice, efficient
  | system. Much better than everybody cramming into the next
  | elevator that arrives and selecting a bunch of floors.
 
  | bobbylarrybobby wrote:
  | At the end of the workday, not having several full elevators
  | stop on their way down to the lobby to try (and fail) to take
  | you down from the second floor is a godsend to everyone
  | involved.
 
    | ncmncm wrote:
    | 2nd floor? You need the exercise.
 
  | ThePadawan wrote:
  | I live in a building that has this. As a resident - it works.
  | 
  | Whoever made this building made a whole lot of mistakes though:
  | 
  | - They put this into a building with public spaces (e.g. a
  | doctor's office).
  | 
  | - When standing in front of the elevators, nowhere does it say
  | which office is on which floor (it says so in the lobby which
  | you walked by to get to the elevators)
  | 
  | - The screens where riders have to select floors automatically
  | turn off after not being used for a few minutes. At that point,
  | to people who have never used them before, they do not look
  | like they have anything to do with the elevators at all.
  | 
  | - When these screens do turn on, they list the floors in
  | reverse order (i.e. highest first). That makes sense because
  | the people on the highest floors are the most likely to use the
  | elevators, right? Well, all the offices are on floors 1 through
  | 4. They're on page two of the screen. The button for "next
  | page" is not labelled as such. You have to know it's there.
  | 
  | - The screens are resistive touch screens and not well
  | calibrated. The buttons to select a floor are approximately the
  | same height as the tip of your index finger. A first time user
  | won't hit the correct floor the first time, guaranteed.
  | 
  | - At the point where you are standing in front of the
  | elevators, you are so deep into the building that you have 0
  | cell reception. I have randomly encountered food delivery
  | people be stranded there because they could not call their
  | customers to figure out how to use the elevator.
  | 
  | Every single week I have to rescue a poor 80 year old person
  | who needs to go to the doctor and is horribly lost and
  | confused, and it just breaks my heart how the building's owner
  | (which I've contacted about this to no avail) chose "oh the
  | salesperson said this was more efficient and trendy" and now a
  | large percentage of users are so much worse off for that
  | choice.
 
    | ehvatum wrote:
    | I wonder if there is any improving that system without
    | replacing it.
 
      | xmodem wrote:
      | Most of the problem described here is the input mechanism.
      | The building I work in has "destination dispatch" too but
      | instead of a touchscreen, it has a large numeric keypad
      | that you type your floor number on, with physical buttons
      | that look like normal elevator buttons. We do also have
      | some floors that are open to the public and i've only seen
      | people confused by it a couple of times in several years of
      | working here.
 
      | ThePadawan wrote:
      | There are some easy fixes to the things I described - like
      | adding a list of offices and floor numbers above the
      | touchpads, or adding a phone signal boosting indoors
      | antenna.
      | 
      | Apart from that, the first thing I wondered when I moved in
      | was "oh, as a resident, does that mean I just get a keyfob
      | I can wave at this screen that knows I live on the X-th
      | floor?". That's also feasible, to the degree that the
      | Wikipedia article linked above refers to this.
      | 
      | The problem with all these fixes is of course that they all
      | cost more than $0.
      | 
      | And neither the company owning this building nor any
      | landlord company involved in its operation is even based in
      | the same ZIP code as the building. So why would they care?
 
        | 8organicbits wrote:
        | > So why would [the landlord] care?
        | 
        | A complaint from one of many residents may be futile, but
        | a complaint from the retail tenant with the largest space
        | would carry more weight. Surely showing that this
        | elevator decreases the value of their building would be
        | something they'd care about, if delivered correctly.
 
| chis wrote:
| Is there any intuitive explanation for why the mean minimizes the
| squared error? I know it IS true - this property is used for
| linear regressions etc - but I couldn't actually explain it.
| 
| It seems like whatever minimizes a squared error should itself
| have some squares in it.
 
  | shikoba wrote:
  | If you know about inertia, the grabiy center is where inertia
  | is minimized. But it's just a way to rephrase it.
 
| xcskier56 wrote:
| Whelp, now I'm gonna think about minimizing the distance to every
| elevator every time I'm in front of more than 2 elevators...
| thanks
 
| kazinator wrote:
| > _So standing in front of the second elevator minimizes the
| expected distance to the next elevator, assuming all three
| elevators are equally likely to arrive next._
| 
| > _What if you want to minimize the worst case instead of the
| average case? Stand half way between the first and third
| elevators._
| 
| What is the difference between "in front of second" and "halfway
| between first and third"?
 
  | troglonoid wrote:
  | In the first paragraph he says the elevators aren't evenly
  | spaced, and then again, it is mentioned in the James Hadley
  | quote.
  | 
  | In this scenario, the second elevator isn't centered between
  | the first and the third elevators.
  | 
  | If I understand the description properly, the layout may be
  | something like this:
  | 
  | []__[]____[]
 
  | sanderjd wrote:
  | The elevators are not evenly spaced. This point is in the
  | article but could have been belabored a bit more. If they are
  | evenly spaced, there is no difference.
 
  | mikkergp wrote:
  | I assume this must mean that the elevators are not equidistant
  | from eachother. As in 1 is 10 feet from 2 is 20 feet from
  | three.
 
  | PebblesRox wrote:
  | They're not necessarily evenly spaced. The middle elevator
  | might be a lot closer to one side than the other.
 
  | Jtsummers wrote:
  | From the problem statement (first two sentences of the post):
  | 
  | > Imagine a bank of three elevators along a wall. The elevators
  | are in a straight line but they are not evenly spaced.
 
| throw__away7391 wrote:
| Well ok, but if you listen carefully you can hear which elevator
| is coming/closest and always be standing directly in front of the
| one that is arriving.
 
| [deleted]
 
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