Real-Time Data in GTFS-realtime Format
GTFS-realtime is a standard developed by Google for delivering real-time data. It is in Protocol Buffer format and needs to be combined with General Transit Feed Specification (GTFS) schedule data to be meaningful. The result is a highly efficient way to deliver data about all routes and vehicles at once using a minimum of bits. The MBTA makes alert data for all MBTA service, and real-time data for all services that have it, available via GTFS-realtime.
Documentation for the MBTA's GTFS-realtime feed can now be found at the MBTA-realtime developer portal.