7 ms·

Citymapper has this bizarre flaw (in London at least) where it relies on average times to give you journey times. So, for example, if your train takes 10 minut

by bonaldi 12y ago

Citymapper has this bizarre flaw (in London at least) where it relies on average times to give you journey times. So, for example, if your train takes 10 minutes to reach your destination, leaves your local station every 30 minutes and you've just missed one, CityMapper will show an estimated journey time as 25 minutes (avg wait 15 minutes + 10 min journey), instead of the actual 39. On multi-train journeys like many Londoners have, that error compounds quickly, and it can make choosing the fastest route near-impossible. And I don't know why they do it, because they have all the timetable data (including live timetables).

andrewingram 12y ago
They also have harder problems to solve when it comes to buses. During the tube strikes, it was incredibly frustrating to have all the route suggestions involve getting the 29 in Camden. Anyone who's attempted to get the 29 from Camden late at night will know what I'm talking about. Essentially they need to start including knowledge not just about how frequent transport is supposed to be, but the typical number you'll have to miss before you can get on. For the 29 in Camden this number is around 5. But, as Citymapper becomes more ubiquitous within each city, this becomes a solvable problem. They can use the real-time usage of Citymapper to model congestion, and offer better route suggestions. I'm quite happy to use a journey that's 15 minutes longer if it means I'm warm, rather than standing in the cold for 30 waiting for the 'faster' option.
- EmilLondon 12y ago
  We would love to be able to solve those problems, but we need more humans!
  - pyre 12y ago
    Mental Image: A huge furnace powering a black box labelled "Citymapper Development." There's a ramp up to an opening in the front of the furnace. There are two grunts with full-body jumpsuits that say "Citymapper Employee" on them. They are heaving humans into the furnace. I'm sure you are a great team, but that was the silly mental image "we need more humans" gave me. ;-)
    - madaxe_again 12y ago
      Derived from http://simpsonsscreenshots.com/wp-content/uploads/2012/08/moredogs.png http://simpsonsscreenshots.com/wp-content/uploads/2012/08/mo..., I'm guessing!
    - azmaty 12y ago
      Thats kinda how it is.
- throwaway283719 12y ago
  To be clear for non-Londoners, route 29 has one of the highest crime rates amongst all London bus routes, especially late at night. I'm not sure if it's particularly bad around Camden, although there is probably a higher than average rate of drunken idiots.
  - nm_101 12y ago
    The 29 is a temporary insane asylum
  - easytiger 12y ago
    Most nightbus experiences start off feeling like fun (yey everyone is in party mood!), become somewhat riddle with a threat of general menace (think A Clockwork Orange) and end up, if you are going far enough, being suicidally depressing because you've sobered up. If you end up falling asleep you will end up in essex, alone and abandoned
michaelt 12y ago
I don't know why they do it If you represent every edge on the transport graph with a single fixed traversal cost, you can calculate the lowest cost route between two nodes with well known algorithms like (simple) Dijkstra's algorithm or (high performance) Contraction Hierarchies. When the cost of a route varies with time of day, and the best route changes with time of day, things get quite a bit more complicated.
- BorgHunter 12y ago
  Not as complicated as you might think. You essentially add time as an extra dimension to your graph, true, but because you're dealing with discrete vehicles instead of a continuously varying function, you can take shortcuts that make that portion of it pretty simple. It's the walk to and from the transit stops, in my experience, that's a PITA to deal with when you're trying to do transit routing.
  - michaelt 12y ago
    If you're doing simple Dijkstra and you only want to return a result for a single departure time, you're right that it's not too complicated as you still only have one cost per edge. If you want to do computations in advance, as you need to for fast algorithms like Contraction Hierarchies, you have a cost-vs-time profile for each edge. Things can get complicated quickly.
- deleted 12y ago
  [deleted]
EmilLondon 12y ago
This isn't a bizarre flaw. We favor routes with higher frequencies, as typically users don't want to take routes immediately. (I work on Citymapper's routing.)
- ownagefool 12y ago
  Maybe that's the case but I literally never look at maps except when I'm actually trying to go somewhere. Google maps have the arrive / leave by input that helps with your situation though.
- justincormack 12y ago
  I often want to take routes immediately - can we have a "now" option?
- scoot 12y ago
  Thank you for your work on CityMapper. However may I respectfully suggest you stop developing for a bit, and go out and actually use it for real, 'in the field'? Head out the office, pick a spot to get to (say a meeting in another part of town) and see if you can figure out which route is actually quickest. It's seldom the one suggested. Trying to figure out the real trip length for upcoming departures for a number of travel options is a head-wrecker. I use CityMapper frequently, and I love it. But this 'feature' is infuriating!
  - Brakenshire 12y ago
    > see if you can figure out which route is actually quickest On this question, there's a balance between possible maximum speed, and reliability. If I want to go to point B, the quickest possible route will often be made by stringing together a serious of improbable connections. For instance, the route could rely on taking three infrequent buses, with little leeway for transfer between one and another, on the assumption that they won't be slowed down by traffic (or just slow customers, stopping more than normal, etc). But if an app sends me along this route, and one of the buses is behind schedule, and I miss the connection, that then becomes a big problem. So there definitely is good sense in prioritizing frequent bus routes to some degree.
wjoe 12y ago
I've had really mixed experiences with the time estimates in London. Sometimes it will specifically say that a train/bus will arrive at 17:00, 17:10, 17:20 etc, but sometimes it will just say "every 10 minutes". I haven't worked out the reason for it, I've seen both versions on exactly the same services before. That's pretty much my only complaint about an otherwise perfect app though, but you're right that those little errors can add up to be quite inconvenient over a long or rushed journey.
- angusb 12y ago
  I know it switches from live timetable to "every 10 minutes" style estimates when: - day bus service ends and night buses begin - your phone signal dies Does it do it at other times too?
wrikl 12y ago
I've also experienced issues where the data provided by Citymapper for a desired journey in London is just plain inefficient when compared with common sense. Often the app will suggest a route which takes an extremely long way round (such as suggesting only one journey at something ridiculous like 85 minutes), seemingly optimising for some unintuitive variable (possibly number of changes or as-the-crow-flies distance? I'm not sure) which makes it unfortunately unusable for me. I was excited to try it out since I find the app well-made and seemingly a more focused version of Google Maps. However, Google Maps, given the same destination, provides several routes (and allows for explicit choice by the user for their own weighting) where 99% of the time the quickest route is the one that I had thought of beforehand. And this is when selecting Train + Underground in order to compare directly to the equivalent set of results in CM. A shame.
- quarterto 12y ago
  I've noticed this with bike sharing. It finds the nearest station by crow-flies distance, then finds a walking route to it, leading to absurd situations like https://citymapper.com/london/superrouter?start=51.498377681772226,-0.034160614013671875&saddr=Flat%2098%20New%20Caledonian%20Wharf&end=51.51429786349476,-0.09252548217773438&eaddr=36%20King%20St https://citymapper.com/london/superrouter?start=51.498377681...
  - deleted 12y ago
    [deleted]
macca321 12y ago
Even worse, it has a Boris Johnson icon in it.
azmaty 12y ago
Agreed on trains. Train data hasn't been good historically so we only recently have the ability to improve this. Internal debate, but not sure we agree on more frequent options like tubes and buses. We're experimenting with real-time ETA, but its pretty whack, things could jump around, which may be ok for nerds but not normal people. Stay tuned, we're not in any way finished. This is what we work on. (Founder of Citymapper)
- pnathan 12y ago
  Take a look at OneBusAway (if you haven't already), you might find that useful and thought-provoking.

by bonaldi 12y ago

andrewingram 12y ago

They also have harder problems to solve when it comes to buses. During the tube strikes, it was incredibly frustrating to have all the route suggestions involve getting the 29 in Camden. Anyone who's attempted to get the 29 from Camden late at night will know what I'm talking about. Essentially they need to start including knowledge not just about how frequent transport is supposed to be, but the typical number you'll have to miss before you can get on. For the 29 in Camden this number is around 5. But, as Citymapper becomes more ubiquitous within each city, this becomes a solvable problem. They can use the real-time usage of Citymapper to model congestion, and offer better route suggestions. I'm quite happy to use a journey that's 15 minutes longer if it means I'm warm, rather than standing in the cold for 30 waiting for the 'faster' option.

EmilLondon 12y ago
We would love to be able to solve those problems, but we need more humans!
- pyre 12y ago
  Mental Image: A huge furnace powering a black box labelled "Citymapper Development." There's a ramp up to an opening in the front of the furnace. There are two grunts with full-body jumpsuits that say "Citymapper Employee" on them. They are heaving humans into the furnace. I'm sure you are a great team, but that was the silly mental image "we need more humans" gave me. ;-)
  - madaxe_again 12y ago
    Derived from http://simpsonsscreenshots.com/wp-content/uploads/2012/08/moredogs.png http://simpsonsscreenshots.com/wp-content/uploads/2012/08/mo..., I'm guessing!
  - azmaty 12y ago
    Thats kinda how it is.
throwaway283719 12y ago
To be clear for non-Londoners, route 29 has one of the highest crime rates amongst all London bus routes, especially late at night. I'm not sure if it's particularly bad around Camden, although there is probably a higher than average rate of drunken idiots.
- nm_101 12y ago
  The 29 is a temporary insane asylum
- easytiger 12y ago
  Most nightbus experiences start off feeling like fun (yey everyone is in party mood!), become somewhat riddle with a threat of general menace (think A Clockwork Orange) and end up, if you are going far enough, being suicidally depressing because you've sobered up. If you end up falling asleep you will end up in essex, alone and abandoned

michaelt 12y ago

I don't know why they do it If you represent every edge on the transport graph with a single fixed traversal cost, you can calculate the lowest cost route between two nodes with well known algorithms like (simple) Dijkstra's algorithm or (high performance) Contraction Hierarchies. When the cost of a route varies with time of day, and the best route changes with time of day, things get quite a bit more complicated.

BorgHunter 12y ago
Not as complicated as you might think. You essentially add time as an extra dimension to your graph, true, but because you're dealing with discrete vehicles instead of a continuously varying function, you can take shortcuts that make that portion of it pretty simple. It's the walk to and from the transit stops, in my experience, that's a PITA to deal with when you're trying to do transit routing.
- michaelt 12y ago
  If you're doing simple Dijkstra and you only want to return a result for a single departure time, you're right that it's not too complicated as you still only have one cost per edge. If you want to do computations in advance, as you need to for fast algorithms like Contraction Hierarchies, you have a cost-vs-time profile for each edge. Things can get complicated quickly.
deleted 12y ago
[deleted]

EmilLondon 12y ago

This isn't a bizarre flaw. We favor routes with higher frequencies, as typically users don't want to take routes immediately. (I work on Citymapper's routing.)

ownagefool 12y ago
Maybe that's the case but I literally never look at maps except when I'm actually trying to go somewhere. Google maps have the arrive / leave by input that helps with your situation though.
justincormack 12y ago
I often want to take routes immediately - can we have a "now" option?
scoot 12y ago
Thank you for your work on CityMapper. However may I respectfully suggest you stop developing for a bit, and go out and actually use it for real, 'in the field'? Head out the office, pick a spot to get to (say a meeting in another part of town) and see if you can figure out which route is actually quickest. It's seldom the one suggested. Trying to figure out the real trip length for upcoming departures for a number of travel options is a head-wrecker. I use CityMapper frequently, and I love it. But this 'feature' is infuriating!
- Brakenshire 12y ago
  > see if you can figure out which route is actually quickest On this question, there's a balance between possible maximum speed, and reliability. If I want to go to point B, the quickest possible route will often be made by stringing together a serious of improbable connections. For instance, the route could rely on taking three infrequent buses, with little leeway for transfer between one and another, on the assumption that they won't be slowed down by traffic (or just slow customers, stopping more than normal, etc). But if an app sends me along this route, and one of the buses is behind schedule, and I miss the connection, that then becomes a big problem. So there definitely is good sense in prioritizing frequent bus routes to some degree.

wjoe 12y ago

I've had really mixed experiences with the time estimates in London. Sometimes it will specifically say that a train/bus will arrive at 17:00, 17:10, 17:20 etc, but sometimes it will just say "every 10 minutes". I haven't worked out the reason for it, I've seen both versions on exactly the same services before. That's pretty much my only complaint about an otherwise perfect app though, but you're right that those little errors can add up to be quite inconvenient over a long or rushed journey.

angusb 12y ago
I know it switches from live timetable to "every 10 minutes" style estimates when: - day bus service ends and night buses begin - your phone signal dies Does it do it at other times too?

wrikl 12y ago

I've also experienced issues where the data provided by Citymapper for a desired journey in London is just plain inefficient when compared with common sense. Often the app will suggest a route which takes an extremely long way round (such as suggesting only one journey at something ridiculous like 85 minutes), seemingly optimising for some unintuitive variable (possibly number of changes or as-the-crow-flies distance? I'm not sure) which makes it unfortunately unusable for me. I was excited to try it out since I find the app well-made and seemingly a more focused version of Google Maps. However, Google Maps, given the same destination, provides several routes (and allows for explicit choice by the user for their own weighting) where 99% of the time the quickest route is the one that I had thought of beforehand. And this is when selecting Train + Underground in order to compare directly to the equivalent set of results in CM. A shame.

quarterto 12y ago
I've noticed this with bike sharing. It finds the nearest station by crow-flies distance, then finds a walking route to it, leading to absurd situations like https://citymapper.com/london/superrouter?start=51.498377681772226,-0.034160614013671875&saddr=Flat%2098%20New%20Caledonian%20Wharf&end=51.51429786349476,-0.09252548217773438&eaddr=36%20King%20St https://citymapper.com/london/superrouter?start=51.498377681...
- deleted 12y ago
  [deleted]

macca321 12y ago

Even worse, it has a Boris Johnson icon in it.

azmaty 12y ago

Agreed on trains. Train data hasn't been good historically so we only recently have the ability to improve this. Internal debate, but not sure we agree on more frequent options like tubes and buses. We're experimenting with real-time ETA, but its pretty whack, things could jump around, which may be ok for nerds but not normal people. Stay tuned, we're not in any way finished. This is what we work on. (Founder of Citymapper)

pnathan 12y ago
Take a look at OneBusAway (if you haven't already), you might find that useful and thought-provoking.