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> Destination Dispatch [...] are in general worse I wonder if this is an artifact of how the author used random destinations. I worked in a building that used
by omoikane 2mo ago
> Destination Dispatch [...] are in general worse
I wonder if this is an artifact of how the author used random destinations. I worked in a building that used Destination Dispatch, and the common travel pattern seemed to be:
- Everyone who is not on the ground floor generally want to go to the ground floor.
- People who are on the ground floor generally travel in large groups to the same destination.
This happens because people who worked on the same floor often leave for lunch at the same time, and return at the same time to the same floor. Destination Dispatch helps in this case because it's batching large groups of people with the same destination.
- taftster 2mo agoYes, it's definitely more likely for an individual already in an upper floor to return to ground than a stop above or below. The people queuing up in simulations don't seemingly get this right all the time. Also the group of people going to or returning from lunch is real as well. The grouping factor happens more at the middle of the day and less at the morning or evening. Primarily because of lunch.
- acomjean 2mo agoIs it because the criteria is wait time not travel time? Destination dispatch would avoid some extra stops on the trip. I just visited a new building with destination dispatch, so it seems to be still around. My EE roommate in college had to build an elevator circuit as a final problem. It was on a bread board and had a bunch of call buttons and had a motor and a clear disk with black squares so it could figure out where it was…. I think it was the simple algorithm…
- vova_hn2 2mo ago> Is it because the criteria is wait time not travel time? Yeah, it doesn't make any sense to optimize wait time instead of total time from pressing the button to reaching destination.
- kadoban 2mo agoHuman psychology might allow other reasonable criteria even if perfectly rational choice is just total time to destination.
- esikich 2mo agoIt very well could be the case that people get more upset about waiting for the car than total travel time when they are already in the car. Ie, pick them up sooner even if travel time is longer. In fact, I would bet that this is the case.
- donalhunt 2mo agoHaving chatted with friends who have gotten stuck in elevators, you definitely should care about total travel time. In one case, the building was still being commissioned and it took a while for anyone to even realize they were stuck (could spawn a whole discussion about launch processes in itself).
- esikich 2mo agoObviously. I'm talking about waiting for the elevator for 30 seconds, total trip is 2 minutes vs 1 minute 30 sec wait and total trip is 1m45s.
- Gabrys1 2mo agoIt should be both, I think. Same goes for queuing in the restaurant. Waiting for the table for 5 minutes, then 5 minutes for the waiter, then 10 minutes for the drink, then 25 for the food is better than waiting for the table for 25 and then getting your full order in another 5. Basically you have an irrational sense of progress even if things get delayed
- Ekaros 2mo agoThe criteria might also be throughput. That is moving maximum number of passengers in which case total travel time is likely much better metric than wait time.
- ApolloFortyNine 2mo agoSurely there's a dataset out there with elevator calls for an office building you could test on, instead of the poor random destination case. Surprisingly, claude failed to find a good one. Also, part of destination dispatch (I'm guessing based on experience) removes the 'stopping on every floor problem', so the real test would be total time including wait at that point I think.
- Ekaros 2mo agoI think most of these sort of data sets are considered trade secrets. They are certainly recorded and even stored. But as they could give competitive edge between manufacturers they are not publicly shared. And access to them would mean building maintenance or managers giving access to their occupants information which some of the occupants would not like.
- darkwater 2mo agoYeah, and definitely is not the right story for hotels. His premise of "morning traffic mostly from lobby to floors" is completely false in an hotel where you get it both ways due to people going down for breakfast and going back up and the down once again. I see hotels with the kiosk model changing the UI depending on breakfast rush hour
- whartung 2mo agoMost interesting hotel elevator system I’ve seen was in Washington DC. Instead of hitting the call button, you started the request with your floor. Then the system would assign you an elevator (there were 6 cars as I recall). I assume this gave the system more accurate routing data to make it more efficient for everyone.
- nkjoep 2mo agoIt’s explained in the article
- icosian 2mo ago> Yeah, and definitely is not the right story for hotels. The first time I encountered Destination Dispatch was in a London hotel, maybe 15 years ago. Anyone unfamiliar with the system would naturally sprint towards an open elevator and end up in an elevator with no buttons, totally bewildered. It's not the right system for a transient population.
- donalhunt 2mo agoMaybe they were embracing YOLO - who knows the possibilities of putting your trust in others' decisions / destinations. Or should it be YORO? You only ride once?
- alexpotato 2mo ago> - People who are on the ground floor generally travel in large groups to the same destination. I also thought that this is one of the biggest reasons destination dispatch was better. There are even articles about switching to destination dispatch in office buildings or hotels lead to dramatic reductions in wait time.
- dawnerd 2mo agoCruise ships that use destination dispatch have been much nicer too. Ships that use the older algorithms are a pain to wait during peak times. Guess plus side you’ll use the stairs more.
- pimlottc 2mo agoThis is case where you need to make sure your test data reflects real-world usage or you end up optimizing for the wrong thing. Ideally a new elevator installation would have a trial period where they record usage and then run it through a simulator like this to determine the optimal strategy for that particular building. And you'd want to re-run it every once in a while as the building tenants/usage changes. I wonder if this actually happens, though.
- shepherdjerred 2mo agoI wonder if we'll see LLM elevator scheduling
- fragmede 2mo agoIBM's Watson has been used for elevator scheduling.
- noisy_boy 2mo agoI apologize for bringing you to the 29th floor instead of the 3rd floor as you requested. That's on me. I will do better next time.
- brookst 2mo agoI want to own something here: this is the fourth time in a row I’ve brought you to the 29th floor when you asked for the third. I am creating a memory to always go to the 3rd floor instead of the 29th, which should prevent this from happening again.
- breakingcups 2mo agoSmall wrinkle: the existing documentation indicates that the 29th floor is in fact the 3rd floor.
- ufmace 2mo agoSorry, I forgot that this building only has 18 floors, it's on me that your elevator is now airborne.
- richk449 2mo agoIt is almost certainly because of the way the simulation was performed: It turns out these fancy kiosks are in general worse for wait times compared to the traditional good ol' up and down buttons. There are certainly edge cases when the kiosks can win out (extremely tall buildings with 8+ cars per elevator bank) but for the majority of cases, simple up down buttons reign supreme. This counterintuitive result is all thanks to the rebalancing step where every 5 seconds, the system re-optimizes each elevator's path. The kiosk enforces rigidity, you must get in the assigned elevator. There should be no way that only having more information results in a worse outcome. At minimum, you could ignore the extra information, and achieve the same results as using up and down buttons. Seems like the real reason it performed worse in this simulation is that when they implemented destination dispatch, they assigned an elevator at time of request, and had no system for reviewing and updated that assignment.
- sambellll 2mo ago> Seems like the real reason it performed worse in this simulation is that when they implemented destination dispatch, they assigned an elevator at time of request, and had no system for reviewing and updated that assignment. I don't think it's possible to have destination dispatch AND update assignment together, in the real world. - If the user clicks floor 26 and you tell them to wait at elevator G, you can't really tell them to move to F if it's taking too long. - But if you don't tell them an elevator to wait at, then you'd need them to run around what is possibly like 5-8 elevators to find which one is going to their floor? That's obviously not realistic. So then you're going to just have them get in the first one that opens? But then that's just the same as an up/down button.
- richk449 2mo agoInteresting. I didn't realize that destination dispatch told the user what elevator to take at the time of request. (I've never used it.) Why not have active display above each elevator that says what floors it is going to when it opens?
- NetMageSCW 2mo ago
- account42 2mo agoDestination Dispatch should also allow you to better optimize total travel time rather than just wait time. Especially in the tall office building case you could have an elevator that skips straight to the top floor instead of having to stop for people to get off people all the time.