The routing API backend is connected to real-time information for some routes. This means that API queries can return real-time information.
Note: Real-time information is not always available and somtimes can be potentially slightly inaccurate.
Real-time means in this context prediction of arrival and departure times, trip cancellations, partial trip cancellations and occupancy status for vehicles that operate on routes.
Real-time estimates are enabled by default when making itinerary planning requests. Availability of real-time estimates is not guaranteed, but field realTime (true / false) in each leg of the itinerary will indicate whether that leg's arrival / departure time is using real-time or static timetables. When using real-time, it means that uncertainty for arrival time is less than for purely static timetable data.
Real-time estimates for itinerary planning can be turned off by using the argument preferences: {transit: {timetable: {excludeRealTimeUpdates: true}}} of planConnection query. Setting this to true will mean that the static timetables will be used in routing.
Departures that have been cancelled through a real-time feed can be included using the arguments preferences: {transit: {timetable: {includeRealTimeCancelations: true}}} of planConnection. This means that an itinerary can include a cancelled departure while some other alternative that contains no cancellations could be filtered out as the alternative containing a cancellation would normally be better.
For stop timetables and route timetables, real-time estimates are available from stop times through realtimeArrival and realtimeDeparture fields or from leg's start and end estimated field. Note that in stop times, these fields will have the static arrival / departure time by default and field realtime indicates whether the values of those fields have been updated from a real-time source.
Some vehicles might have real-time occupancy information available. This information can be accessed through Trip type's occupancy field.
Note: Currently, this information is always the current state (or the last known state). There is no occupancy prediction data available.