A GTFS feed is composed of a series of text files collected in a ZIP file. Each file models a particular aspect of transit information: stops, routes, trips, and other schedule data. The details of each file are defined in the GTFS reference.
GTFS Spezification: https://developers.google.com/transit/gtfs/reference/
Routes are equivalent to "Lines" in public transportation systems. Routes are defined in the file routes.txt, and are made up of one or more Trips. A Trip represents a journey taken by a vehicle through Stops. Trips are time-specific — they are defined as a sequence of StopTimes, so a single Trip represents one journey along a transit line or route. A StopTime defines when a vehicle arrives at a location, how long it stays there, and when it departs.
Worldwide: https://transitfeeds.com/feeds Tools
sudo pip install transitfeed
Or get the trunk from
svn co https://github.com/google/transitfeed.git/trunk
Comes with some command line tools
Use transitfeeds feedvalidator.py on a zip file to obtain a detailed report on the data quality.