GTFS or the General Transit Feed Specification defines a common data format for public transportation schedules and associated geographic information.

[1][2] What was to become GTFS started out as a side project of Google employee Chris Harrelson in 2005, who "monkeyed around with ways to incorporate transit data into Google Maps when he heard from Tim and Bibiana McHugh, married IT managers at TriMet, the transit agency for Portland, Oregon".

[4] Bibiana and Tim McHugh eventually got into contact with Google and provided the company with CSV exports of TriMet's schedule data.

This resulted in "hundreds of useful and popular transit applications"[4] as well as catalogues listing available GTFS feeds.

Due to the common data format those applications adhere to, solutions do not need to be custom-tailored to one transit operator, but can easily be extended to any region where a GTFS feed is available.

Due to the wide use of the format, the "Google" part of the original name was seen as a misnomer "that makes some potential users shy away from adopting GTFS".

[7] GTFS is typically used to supply data on public transit for use in multi-modal journey planner applications.

This data is often extended using GTFS-Realtime to factor delays, cancellations, and modified trips into realtime journey planning queries.

[8] Other general purpose applications exist such as the ArcMap Network Analyst extension which can incorporate GTFS for transit routing.

The specification is designed to be sufficient to provide trip planning functionality, but is also useful for other applications such as analysis of service levels and some general performance measures.

In contrast to European transit industry exchange standards such as Transmodel or VDV-45X, GTFS only includes scheduled operations that are meant to be distributed to riders.

This article contains excerpts from "Opening Public Transit Data in Germany" by Stefan Kaufmann, which is available under a Creative Commons Attribution 3.0 unported license.