New Rule Proposal: Individual scheduled trip_id not accounted for in Vehicle Positions feed

[evansiroky]

Summary:

An error should be raised whenever an individual Trip that should be in service at the time a Vehicle Positions feed was downloaded is not accounted for in any VehiclePosition record in the Vehicle Positions feed after accounting for canceled trips noted in the Trip Updates feed.

Steps to reproduce:

Given a TripUpdate dataset
and a Vehicle Positions dataset downloaded close to the same time as the TripUpdate dataset
and their associated GTFS Schedule dataset
When the validator has compiled a list of all trips that should be currently in service
and has scanned through all TripUpdate entities in a Trip Updates feed to determine which trips have been canceled
and has scanned through all VehiclePosition entities in a Vehicle Positions feed
and does not find an individual Trip that was expected to be in service being accounted for in any VehiclePosition record
Then the validator should flag this respective trip_id in question for not having any corresponding VehiclePosition entity describing its realtime status in the Vehicle Positions feed.

Expected behavior:

The GTFS-Realtime Best Practices state:

Feeds should cover the vast majority of trips included in the companion static GTFS dataset. In particular, it should include data for high-density and high-traffic city areas and busy routes.

The GTFS Validator should flag all trip_ids individually that should have been accounted for at the time that the trip should have been in service.

Observed behavior:

An error or warning is not raised for this problem at this time.

etc

• This issue seeks to add more detailed scope to Cover most trips in GTFS Schedule #119.
• This issue may run into problems with batch-processing from multiple files as discussed in Clarify batch processing docs and behavior in context of multiple files, cross message rules (E047) #100