What happens with deprecated data? Solving problems with GPS failure

Skip to first unread message

matevz petan

Nov 18, 2020, 5:59:50 AM11/18/20
to GTFS-realtime

Recently we have decided to implement RTFS-RT reporting. We decided to synchronize only the `Position` attribute in the `VehiclePosition` structure. My question is related to how obsolete data is treated. We are facing a scenario where the terminal (vehicle) could not determine its GPS location. I don't know what the best approach is in solving this problem, and I was hoping to get some feedback and advice how you solve this problem. As I can see there are only three ways to handle this situation:
1. You don't send any data about this terminal (vehicle)
2. You send data, but you set the `Position` attribute to `null` (It's marked as optional)
3. You send the last known location (with some limitations with how old the data can be, before it's marked as deprecated in our own system)

This brings me my second question, how does the google system behave in these scenarios (does google already use the old location, or do they predict the location based on speed, location, etc...)? Also, we have decided to use the `FULL_DATASET` incrementality mode (due to DIFFERENTIAL being still in development).

Also feel free to delete this post if there is already a duplicate post, or if I've missed the board (I could not find any relevant information regarding my problem).

Thanks to everyone willing to help me out,

Ivan Volosyuk

Nov 19, 2020, 8:38:10 PM11/19/20
to gtfs-r...@googlegroups.com
Each vehicle position should have a corresponding timestamp when the
GPS reading was made. When the feed reaches a consumer it is already
somewhat stale, so it is normal to have stale data in the system. When
you send the realtime data to google you will get the feed issues
report from which you will learn that (2) == (1). You should send (3)
if you want the realtime data to be presented to the user. Google
doesn't predict the location of a vehicle, just arrival/departure
times based on the latest available GPS location. That's why it is
important to have the correct timestamp for the GPS reading.
> --
> You received this message because you are subscribed to the Google Groups "GTFS-realtime" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to gtfs-realtim...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/gtfs-realtime/429aff0a-fa04-41bd-a6a3-329e0a166f46n%40googlegroups.com.
Reply all
Reply to author
0 new messages