Google is discussing a stiry named How Google Is Remapping Public Transportation. We did mention quite a few times the GTFS (General Transit Feed Specification) in the past.
Their summary: ""Google wants to 'organize the world's information,' but there isn't a marketplace or a category of knowledge it can organize without remaking it in the process. A case in point: public transportation. Largely outside the media spotlight, Google has wrought a quiet revolution over the last five years in the way commuters get schedule information for local buses and trains, and the way public transit agencies communicate with their riders. GTFS and GTFS-realtime, which Google invented, have become the de facto world standards for sharing transit data, and have opened up space for a whole ecosystem of third-party transit app developers. This in-depth article looks at the history of GTFS and Google's efforts to give people information (largely via their smartphones) that can help them plan their commutes on public transportation — and, not incidentally, drive a lot less.""
Specifically on the GTFS-realtime standard from the article: "To enable all that, Google introduced a new standard in 2011 called GTFS-realtime. It builds on GTFS, but is a different animal, since it includes new feed types for trip updates, service alerts, and vehicle positions, as well as provisions for constantly refreshing this data throughout the day. In an advisory to agencies, Google puts it this way: “Because GTFS-realtime allows you to present the actual status of your fleet, the feed needs to be updated regularly—preferably whenever new data comes in from your Automatic Vehicle Location system.”"