I thought of an interesting idea, then searched to see if anyone had done it. It seemed like not, so I wrote the below post. Then I looked once more, and found a few instances (finding one makes it easier to find others). I still think the proposal is good, and I have not much idea whether anyone doing it competently. However it is not so novel as hoped, and one must wonder why such things have not been successful enough for me to have heard of them (even after trying unusually hard to hear about them).

Instead of modifying the post, Robin Hanson suggested I put it up more or less as it was before I knew such a thing existed, and then I can compare the details of my suggestion to the details of systems that are real (or real minus any widespread adoption). This can make for a rare test of how different things look if you have an actual business providing a service, versus a daydream about an actual business providing a service. This seems like a good idea to me, so here you have it. The changes I made were adding this part, and removing a half-written couple of sentences at the end about how there didn’t seem to be anyone doing this, though there are some related things. I mean to compare it with a real system another time.

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Consider how much time people spend in queues. Here is a proposal for reducing that dramatically, with a smartphone app.

The app controls a virtual queue. You tell your phone you want to join the queue. You continue shopping or whatever. Your phone pings you when you are near the front of the queue. You wander over and get in the physical line just before it is your turn.

There are many details to iron out here, but there seem to be plausible solutions:

1. How can people smoothly use this when there will be a large fraction of people who don’t have it?
   In the simplest case, places that have multiple queues could have one dedicated one. Where this is not practical, the owner of the queue might have a smartphone or tablet at the front running a different version of the software which would allow others to add their names to the queue – in which case they can stand around as usual until called – or their phone numbers and a time estimate, in which case they can also wander a bit.
2. How do you know how long the queue is?
   The app could trivially tell you this. Ultimately, it could also probably give you better stats on how much time it will likely take to get through it.
3. How does the person serving the queue know how long the queue is? The queue owner has their own version of the app which shows them the current queue. This allows them to tell the app when the next person is up, make judgements about staff allocation, resolve any disputes about who’s turn it is. The same device might be used to add people to the queue who don’t have the app.
4. How does the app know whether you have taken your turn?
   You get a final ping, telling you it is your turn. You respond to it by saying that you are doing so, or not. If you say not, then someone else is immediately called up, so if you do it wrong, it will probably be clear. The queue owner also has control of the queue, so if anything confusing happens, they can ask who you are, and tick off the right person on their app.
5. What if you don’t get there in time?
   You could be moved to the next position in line a couple of times before being pushed out of it entirely.
6. How does your phone know how long you need to get to the queue? Or do you just have to be within a few minutes of the queue all the time, for instance?
   In the simplest version, having a blanket few minute warning would be plenty useful in many cases. Google now already tells you when you should be leaving to get to a place though, so I assume similar functionality is feasible in the long run.
7. If you can’t go that far away, would this really be so useful?
   Take the supermarket case. In the worst case, it is probably more amusing to wander around nearby than stand in a queue. In more optimistic but fairly plausible cases, you can do your important shopping then get in queue, then do any more discretionary shopping, and thereby save time. More optimistically, if you come to trust the time estimates, you could start your shopping even after you got in line, and only be not that far away at the very end.
8. Why would anyone to take this up?
   In the long run, this system seems likely to be much better to me. But in the short run, it might  be confusing or annoying to customers or staff, or not be very smooth, or doing things differently might just be risky in general. There are some inducements to take it up at the start though. Obviously, it might quickly work well, look innovative, and be much less annoying than a queue. Also, at the start, it should cause more customers to wander around your shop while they wait, probably encouraging them to buy more things from you. If you have multiple queues, you might avoid the downside from people feeling forced to do a new thing, and also be able to more gently encourage them to download the app, as they see an inviting looking empty queue. I think another good case is probably restaurants. Many restaurants currently try to have a system like this, using a pen and paper, and people wandering back pretty often and checking in, or sitting around in the sidewalk. Often the queue takes a long time, so it is valuable to be able to leave. In this situation, I think many people would be happier to just get a ping when it is their turn, especially if in the meantime they can see roughly how long the wait is without walking back. In general, queues are pretty annoying already, so it seems it shouldn’t be that hard to be less annoying.
9. How do you know who is really first if there is someone already there?
   If you get a ping when it is your turn, this should be clear.
10. Can you join the queue way early, then wander in whenever you feel like it?
    If, when you miss your place, you are given too large a window to come back in, then you might have many people who could just turn up at any point, making it hard to know the real length of the queue. Thus you may want to avoid this. Though if you have a fairly good sense in practice of how often such people show up, it might not be that bad.
11. Is it too annoying for people to download an app, and subsequently open it?
    Again, it seems best if this kind of thing starts in contexts where there are multiple queues. Also, even if downloading an app is annoying, remember that your alternative is standing in a queue for ten minutes. Standing boredly in a queue also seems like a pretty likely context for someone to download an app, especially an app that will allow them to not do that again. Alternatively, you could partner with a pre-existing app running related services.
12. Probably many others that don’t strike me at this moment.

In the long run, there would be other useful services you could add. People could get in line whenever, and the app could tell say when to leave home. They could say ahead of time when they want to get to the front of the line, and be added at roughly the right time. The app could support purchase of better places in line from willing traders. You could naturally have good data on traffic, allowing better provision of services.

Overall, it just seems unlikely to me that the best wake to keep track of a list of people in these modern times is to physically line them up.