[REQUEST] Implement shapes exists for a trip verification (GTFS rule)

[maximearmstrong]

Is your feature request related to a problem? Please describe. A trip should be related to an existing shape. The related shape must have a non null length. This is a GTFS rule implemented in Google Python validator and featured in Google Type Error as TYPE_TRIP_WITH_SHAPE_DIST_TRAVELED_BUT_NO_SHAPE and TYPE_TRIP_WITH_SHAPE_DIST_TRAVELED_BUT_NO_SHAPE_DISTANCES

Describe the solution you'd like Actual Google GTFS validator behaviour : verifies if shape id exists in shapes list. See comment below for logic.

Generate WARNING called trip_with_shape_dist_traveled_but_no_shape

Describe alternatives you've considered

Additional context Line 143 and 144 in Error support priorities https://docs.google.com/spreadsheets/d/1vqe6wq7ctqk1EhYkgtZ0_TbcQ91vccfs2daSjn20BLE/edit#gid=0

[barbeau]

To clarify, this rule is actually conditional across a few tables, starting with stop_times.txt shape_dist_traveled - if shape_dist_traveled exists for a trip in stop_times.txt, then for that trip_id the file trips.txt field shape_id must be populated, and shapes.txt must contain records for that shape_id.

[lionel-nj]

@timMillet @barbeau Is it guarantied that field shape_dist_traveled is expressed in km in all GTFS datasets? Or does it variate amongst data provider (feet vs meter vs kilometers)?

I found an example from the specification using kilometers: http://gtfs.org/reference/static#stop_timestxt:

Example: If a bus travels a distance of 5.25 kilometers from the start of the shape to the stop,shape_dist_traveled=5.25.
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[barbeau]

No, units for shape_dist_traveled can vary - no official unit is provided. Only that the distance units have to match stop_times.txt.

[emmambd]

It looks like this issue wasn't fully resolved: the unused shape notice checks if there's a shape_id in shapes.txt that isn't used in trips.txt, but it doesn't check if there's a shape_dist_traveled value in stop_times.txt that doesn't have a shape_id in both trips.txt and shapes.txt.