VehiclePosition.current_stop_sequence gets "stuck" while vehicle moves

[barbeau]

Summary:

From https://groups.google.com/forum/#!topic/gtfs-realtime/rZcgTvd-7Gc:

I came across a situation earlier today in a vehicle position feed where the current_stop_sequence for a trip was stuck at a value of 2 and the current_status stuck at "STOPPED_AT".

I say stuck because for the same vehicle the position coordinates were been continuously updated and you could see that the vehicle was progressing along the route pretty much in agreement with the TripUpdate predictions.

For trips I give a verbal description of where a vehicle is using current_stop_sequence and current_status and also use these values to mark a vehicle on a trip diagram. However, I also plot the trip and vehicle position on a map using the coordinates and see the contradiction.

We should add a rule to the validator to try and determine if VehiclePosition.current_stop_sequence gets "stuck" at a stop that the vehicle has already passed instead of progressing with the trip.

Steps to reproduce:

Run validator against agency with "stuck" VehiclePosition.current_stop_sequence

Expected behavior:

Validator should flag this as an error

Observed behavior:

No such rule exists to flag it as an error