GTFS performance checkpoints

[Developer at MBTA]

Dear developers,

We will be implementing a new field to an existing file as well as a new file to GTFS beginning next Tuesday, September 5, checkpoint_id and checkpoints.txt, respectively.

The checkpoint_id field, added to the end of the stop_times.txt file, will be useful for eventually supporting additional services on our MBTA-realtime API for performance data. Certain key stops on bus routes, and all stops on subway, will contain a checkpoint ID. A checkpoint represents a location along a route at which on-time performance is measured. A single checkpoint_id can be shared among several nearby stops on different routes in different directions. Checkpoints each have a corresponding human-readable name in the new checkpoints.txt file.

Now, you may be reading this and thinking, "Isn’t this what a timepoint is?" A "timepoint" already has a specific meaning in GTFS: a stop_time that is a "timepoint" indicates that if the vehicle arrives early, it will hold there until its scheduled departure time, rather than leave early. In this case we’re focused on using this stop to see whether the vehicle is running early or late — hence "checkpoint".

The MBTA GTFS documentation, which can be found at http://realtime.mbta.com/Portal/Content/Documents/MBTA_GTFS_Documentation.html, features these upcoming changes, and a sample of the revised stop_times.txt for several trips and checkpoints.txt can be found at https://drive.google.com/file/d/0B0AUBl3WssWRakMyaE55LXRCUUU/view?usp=sharing.

Sincerely,

developer@mbta

[Developer at MBTA]

Dear developers,

These additions are now live as of late yesterday.

Sincerely,

developer@mbta