> ## Documentation Index
> Fetch the complete documentation index at: https://docs.bayareatransit.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Bulk feeds

> GTFS, GTFS-Realtime, GTFS+ companion files, and historic regional feed notes.

## GTFS operator list

The GTFS operator list identifies which agencies have feed downloads available and also identifies the operator id used for the regional feed.

## GTFS feed downloads

The bulk GTFS download endpoint returns a zip file for a specific operator or the regional feed. The transit specification also documents support for historic regional feed access.

The underlying GTFS tables are `agency.txt`, `routes.txt`, `trips.txt`, `stop_times.txt`, and `stops.txt`, but the important relationships are between the agency, route, trip, stop-time, and stop entities.

## GTFS-Realtime

The transit specification documents three GTFS-Realtime families:

* trip updates
* vehicle positions
* service alerts

For protobuf field semantics, the PDF points readers to the upstream GTFS-Realtime specification.

## GTFS+ files

Appendix D documents several additional files that accompany GTFS datasets:

* `directions.txt`
* `calendar_attributes.txt`
* `farezone_attributes.txt`
* `rider_categories.txt`
* `fare_rider_categories.txt`

In the GTFS+ files these appear as `farezone_attributes.txt`, `fare_rider_categories.txt`, and `rider_categories.txt`, but the useful mental model is the relationship between stops, fare zones, fares, and rider categories.

## Historic regional feed

Appendix E explains how the historic regional GTFS feed is derived, including feed slicing, copying shared entities, hashing and comparing trips, and differences between live and historic regional feeds.