The article didn't explain what a GTFS feed was, and my first thought was it's a "Get The Fuck Somewhere feed". Turns out it's General Transit Feed Specification.
It has all the bus stops and times for applications to use. Metros usually generate them to send to google for their app but they sometimes also publish them online for people to use.
https://sf.streetsblog.org/2010/01/05/how-google-and-portlan...