New Rule Proposal: Feed-wide threshold of ServiceAlert records having missing/stale timestamp

[owades]

Summary:

A warning should be raised whenever a feed-wide threshold has been met among all entities that have a missing or stale timestamp.

Steps to reproduce:

Given a ServiceAlert dataset
When the validator has scanned each individual ServiceAlert record and detects that a certain feed-wide threshold of those records have a timestamp that is missing or stale
Then the validator should flag the ServiceAlert feed in question for having a feed-wide problem of missing or stale timestamps being set

Expected behavior:

The GTFS-Realtime Best Practices state:

Data within a GTFS Realtime feed should not be older than 90 seconds for Trip Updates and Vehicle Positions and not older than 10 minutes for Service Alerts.

The GTFS Validator should flag an error whenever a certain percent of ServiceAlert records do not have a timestamp value added or one that is added but is far enough in the past that it is stale.

Observed behavior:

Timestamps are currently only checked at the feed-level.

etc:

• This will need some definition of what percent of ServiceAlert records would need a missing/stale timestamp in order to be flagged.