GTFS-RT > `TripDescriptor` matching improvement

[mmathieum]

trip_id is quickly outdated/out-of-sync between local static and online real-time data.

For non-frequency based schedule (99%):

• trip_id (& start_date) (& start_time?)
• route_id & direction_id (& start_date) & start_time
• start_date is optional because we can guess the "current" trip by picking the closest one.

Current MT implementation:

• if TripDescriptor contains a trip_id, it must match
• if TripDescriptor contains a route_id, it must match
• if TripDescriptor contains a direciton_id (& not ignored), it must match
• (Alerts only) must also match on stop_id, route_type, agency_id if in TripDescriptor

Current MT fallback for trip IDs mismatch:

• Service Alerts: primary target UUID (route+direction+stop)
• Vehicle Positions: primary target UUID (route+direction)
• Trip Updates: (none)

Issues:

• TripDescriptor's direction_id different than 0 or 1
  • should be always ignored by default GTFS-RT > static<>real-time matching (out-of-sync trip_id...) & tests #117
• Service Alerts: trip_id should be optional if route_id, direction_id and stop_id are used appropriately.
  • GTFS-RT > static<>real-time matching (out-of-sync trip_id...) & tests #117
• Vehicle Positions: trip_id should be optional if route_id and direction_id are provided
  • GTFS-RT > static<>real-time matching (out-of-sync trip_id...) & tests #117
• Trip Updates: trip_id are the best match when in-sync, alternatives can be quite complex
  • ?
• how do we know if trip_ids are outdated/out-of-sync between static & real-time data? or if we just don't have any data for the current TripDescriptor (filter)?
  • should we parse the real-time response and check if the 1st trip ID is inside the local DB to know if trip IDs match or not?
• once we know trip ID do not match, how can we try to match local trip IDs with real-time trip IDs GTFS-RT > static<>real-time matching (out-of-sync trip_id...) & tests #117
  • use TripDescriptor- > start_time if provided to match with local data? then StopTimeUpdate.stop_id must match?
  • ...

Links:

• Select a trip with TripDescriptor - Transit Partners Help
• https://gtfs.org/documentation/realtime/feed-entities/service-alerts/#entityselector
• https://gtfs.org/documentation/realtime/realtime-best-practices/#tripdescriptor
• https://gtfs.org/documentation/realtime/feed-entities/trip-updates/#tripdescriptor

[mmathieum]

OC Transpo: trip IDs to not match at all. Even stop IDs do not match 😞