[HN Gopher] I built my own CityMapper
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I built my own CityMapper
Author : ashfn
Score : 97 points
Date : 2025-10-27 11:18 UTC (5 days ago)
(HTM) web link (asherfalcon.com)
(TXT) w3m dump (asherfalcon.com)
| aaronbrethorst wrote:
| Before Citymapper existed, there was OneBusAway, a Ph.D. student
| project at the University of Washington.
|
| It still exists and powers millions of transit rider trips every
| day all around the world in Seattle, Washington DC, New York
| City, Poznan Poland, Buenos Aires Argentina, Adelaide Australia,
| and who knows where else.
|
| If you're interested in hacking on something like Citymapper, or
| setting up an OBA server for your own city, you can find
| everything you need on our GitHub organization:
| https://github.com/OneBusAway
|
| That includes docker images, an iOS app and a trip planner
| framework, android app, Sveltekit web app, and even a next
| generation OBA server written in Go.
|
| As far as the data to power this, you can get GTFS for every US
| transit agency from https://mobilitydatabase.org/
|
| (nb I've been involved in the OBA project since 2012)
| aaronbrethorst wrote:
| and if you want to get involved, join our Slack
| https://join.slack.com/t/onebusaway/shared_invite/zt-32w08cz...
| or just shoot me an email! aaron@onebusaway.org
| Alive-in-2025 wrote:
| Thanks for your great work on one bus away. This is such a
| fantastic app for people riding the bus. It uses info from the
| bus system to tell you how far the bus is away from your stop.
| It deals pretty well with the messy dynamic reality that
| traffic can slowdown or speed up, or even a bus has to stop for
| some reason and so the next one will come.
|
| Check it out if you are in one of their cities.
| milliams wrote:
| Why are the table and the description of the RAPTOR algorithm in
| the article images rather than text?
| denysvitali wrote:
| During university, we've built OptiTravel
| (https://github.com/denysvitali/optitravel) to do something
| similar. We couldn't use Google Maps APIs (project requirement),
| so we wrote a custom routing algorithm based on A* and I've
| created a Rust server to host GTFS data
| (https://github.com/denysvitali/gtfs-server) a la Transitland
| (https://transit.land/).
|
| Performance wasn't great since everything had to run locally and
| do network roundtrips, but it found routes in my hometown that
| Google Maps didn't show. Pretty cool discovering hidden
| connections in the transit network and being able to customize
| your own params
| (https://github.com/denysvitali/optitravel/blob/master/src/ma...)
| danielhep wrote:
| I am involved with the OpenTripPlanner project, which is a Java
| trip planning application that also uses the RAPTOR algorithm!
| It's used in cities all over the world, with the biggest
| deployment being ENTUR's in Norway, which covers the entire
| country. I believe all trip planning apps in Norway use this
| deployment.
|
| It supports many features and has a very active developer
| community.
| mwagstaff wrote:
| Very nice! I've also used the Rail Data Marketplace (terrible
| name) to build an app that uses the live departure board data
| (https://apps.apple.com/gb/app/traintrack-uk/id6504205950), and
| it's great the data is freely available.
|
| Whilst HN is on the case, does anyone know of an API (inside Rail
| Data Marketplace or elsewhere) that acts as a journey planner for
| UK national rail, i.e. you can input source + destination
| stations and it will output journey options?
| ashfn wrote:
| It looks like TFL's journey planner API has the ability to do
| some of these national rail trips, only tested a few though
| mwagstaff wrote:
| Unfortunately, I believe it's limited to TfL stations only
| (e.g. Overground) rather than National Rail.
|
| Oh, and I should have mentioned that I'm also aware of this,
| but it's not free so automatically outside of my app
| development budget. :/
|
| https://www.nationalrail.co.uk/developers/online-journey-
| pla...
| ashfn wrote:
| I tried a route from a London tube station to Newcastle
| train station and it found one on the frontend for the tool
| so I think it may support national rail
| idlemind wrote:
| Check out api.tfl.gov.uk which should have everything you need
| for London in a more structured format.
| ashfn wrote:
| I used this exact API extensively for both buses and tubes :)
| basisword wrote:
| Citymapper et al are excellent. The big issue I find is that half
| the time TFL seems to completely ignore its own bus schedule (at
| least in my area). You rush for a bus and it leaves 2mins before
| schedule (and the next one also turns up early). I would rather
| longer waits and better predictability.
| ashfn wrote:
| Im thinking it might be better to revisit the project and
| analyse long term patterns in bus arrivals
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