We wish the data displayed by the OneBusAway app were always 100% accurate. It’s pretty good, and we continue to work with the suppliers of the data to try and improve it, but alas it is sometimes incorrect.
Please note that the OneBusAway app does not itself have schedule data or generate real-time arrival predictions. The way OneBusAway works is that the app gets its information via your phone’s internet connection from a server. Each region that provides OneBusAway runs its own server, and that server provides both the schedule data and real-time data. These in turn come from the transit agency that runs the bus/train service and provides the data.
That said, we do send actionable feedback on to the transit agency involved — both the iPhone and Android apps have a feedback mechanism to make this easy. Such rider reports are valuable in particular to help the agency fix a bug in their schedule data, or to the app developers if there is a bug in the app itself. On the iPhone, this is done via the “Info” button on the lower right of the screen, then “Contact Us”. On Android, you can choose “Send feedback” from the main menu navigation drawer.
One kind of error is caused by the server having incorrect schedule data. (OneBusAway’s prediction mechanism is built around the idea of a schedule, and then possible deviations from that schedule based on the real-time data.) So for example if you are at a stop, and a bus is not showing up at all on the display that the agency’s schedule says should be there, this might be caused by incorrect schedule data. This sort of error doesn’t happen that often, but is straightforward to fix if it does, and rider feedback is important in detecting it. (The most likely time for this to happen is after a major schedule revision.)
Another kind of error can result from the server not getting any location information at all from the bus or train. If this happens, rather than having the vehicle disappear completely, OneBusAway displays the schedule information for that trip. So be sure and look for arrival times that are marked “Schedule Only” (for example, the last 10:15pm trip in the screenshot below). If that is the case, OneBusAway doesn’t have any real-time information about that bus — maybe it will be on time, maybe late, maybe even cancelled. (We hope to have cancelled trip indications in the future, but right now this is not part of the data.) This is the main source of “ghost buses” — that is, buses that OneBusAway says are coming but then seem to vanish. Another source of errors is inaccurate predictions from the software that takes the raw location data for the bus or train, and turns it into a prediction like “1 minute late” (imagine a bus, for example, that is anticipated to arrive 5 minutes late but that miraculously hits a green light at every intersection and makes up the lost time).
Yet another possible source of errors is if the bus is off-route. As noted above, OneBusAway data is built around the notion of a schedule and deviations from the schedule, so unfortunately this does not work well if the bus goes off the regular route. (In particular, the King County Metro data in Washington State does not include snow reroutes.)