A theoretical schedule shows the network’s planned stop times. A real-time schedule uses updated information to announce an expected arrival or estimate. That estimate can change: it reflects the known situation but does not guarantee the bus will arrive at the exact minute shown.
Understanding this difference helps you better prepare waiting time and connections.
Understanding the theoretical schedule
The theoretical schedule belongs to the planned service. It depends in particular on the line, the stop and the service calendar. A schedule valid on a weekday does not necessarily apply on Sunday or during a specific period.
Before reading it, check the date, the direction and the stop. Network documents can define separate calendars. The GTFS documentation describes the schedules and calendars used to represent this planned service.GTFS Schedule reference.
A theoretical schedule remains useful when real-time is not available, provided you recognise it as a planned stop.
Find transport stops nearby.
Explore stops listed around a city or your location. Check the details for transport modes and available information.
Understanding a real-time estimate
Real-time can update arrivals, report a cancellation or convey other service information. The GTFS-RT format notably allows updates to stop times. Published data vary by network.GTFS Realtime — Trip Updates.
The label “real-time” does not mean you are directly viewing a measurement of the vehicle at your stop. The app may present an estimate calculated from the available information.
Recognising the type of schedule shown
Look for a legend, an icon, the words “scheduled” or “real-time”, and a possible refresh time. Presentation depends on the tool: a countdown in minutes alone does not identify its source.
Check whether the displayed time corresponds to a planned stop or an updated estimate. A scheduled time may be shown when real-time is unavailable.
Illustrative example: a stop is scheduled for 8:10. An updated estimate later shows 8:14. The first time describes the plan; the second describes the estimate known at that moment. Keep this distinction if the estimate changes again.
Why the estimate can change
Vehicle progress and newly received information can modify the announced arrival. A transmission interruption or a recalculated estimate can also change what the app displays.
A change in the display alone does not reveal what happened. Check service information rather than automatically attributing the change to a delay.
Our article on schedules that change in apps explains useful checks.
Using schedules to prepare your departure
For an important appointment or connection, add a margin. Verify the stop, the correct direction and any disruptions. If only a theoretical timetable is available, present yourself taking into account its planned nature.
The presence of a stop on a map does not guarantee real-time data exists for that stop. You can consult ROOTE for available information in the covered area and supplement with the network. Our guide to finding a nearby stop helps you verify the location.
Scheduled data, estimates, and observations: three different moments
A scheduled time describes the service plan. An estimate announces a future event based on updated information. An observation describes an event or state observed at a specific moment. Real-time data can feed into an estimate: it therefore does not always mean that the passage has already been observed.
Educational example: the bus is scheduled for 8:10 am. At 8:05 am, an estimate announces 8:14 am. The vehicle finally passes at 8:16 am. The schedule, the forecast, and the observed passage answer three different questions. None of these example times describe an actual service.
A vehicle position observed at 8:05 am does not prove a passage at your stop at that time. Likewise, the time at which your application receives data does not replace the time of the original observation. If an estimate is no longer updated, keep its distinction from the theoretical schedule.
For the traveler, look for the type of information and its update date. For the application, keep separately the scheduled time, the forecast, and its timestamp; do not display a fallback theoretical time with the same label as a recent estimate.
| Information | Question it answers |
|---|---|
| Scheduled | What passage is listed in the service plan? |
| Estimated | When is the passage expected according to available data? |
| Observed | What event or state was observed, and when? |
The formats that carry this information
Frequently asked questions
Is a minutes countdown necessarily real-time?
No. Check the tool’s legend or description.
Does an estimate guarantee the announced arrival?
No. It can change with received information and service conditions.
What if real-time is missing?
Consult planned schedules and official network information, allowing an appropriate margin.