Google Transit GTFS Realtime Reference and Differences

Page Summary

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• This document outlines the differences between the official General Transit Feed Specification (GTFS) Realtime and Google Transit's implementation.

• Google Transit ignores certain official GTFS Realtime fields, interprets some differently, and offers experimental support for others.

• Fields ignored by Google Transit include those related to alerts, carriage details, position, shapes, stop time updates, trip updates, and vehicle descriptors.

• Google Transit's interpretation of certain fields, such as stop_id and schedule_relationship , deviates from the official GTFS definition, with specific conditions and supported enum values.

• For information about differences between the GTFS Schedule and Google Transit implementation, refer to a separate article linked in the content.

This page describes the major differences between the official GTFS Realtime and Google Transit’s implementation of the specification in the following areas:

• Ignored official specifications:These fields are part of the official GTFS. Google Transit ingests this data without error but doesn't proactively use the data.

• Different interpretation:These fields include the parts of the official GTFS that Google Transit interprets differently than the GTFS definition of those parts.

• Experimental support:These fields are experimental in Google Transit’s implementation. If you want to implement a new experimental field, contact the Google Transit team .

• Google Transit-supported extension:This extension is not part of the official GTFS. The Transit-supported extension includes both public extensions and Google Transit-specific extensions. Any partner can send this information to Transit in their feed.

Realtime transit

The following sections document the major differences between the official GTFS and Google Transit's implementation of the Realtime transit feed.

Ignored official specifications in the realtime feeds

Some ignored specifications are experimental. To learn more, go to gtfs.org .

Table 1 lists the GTFS-defined fields that are ignored by Transit in the realtime feeds.

Table 1. Ignored official fields in realtime feeds

Message	Ignored field defined in the GTFS	Field type
message Alert	image	TranslatedImage
message Alert	image_alternative_text	TranslatedString
message Alert	severity_level	Enum
message Alert	tts_description_text	Proto
message Alert	tts_header_text	Proto
message CarriageDetails	id	String
message CarriageDetails	occupancy_percentage	int32
message Position	bearing	Float
message Position	odometer	Double
message Position	speed	Float
message Shape	encoded_polyline	String
message Shape	shape_id	String
message StopTimeUpdate (in TripUpdate )	arrival.uncertainty	int32
message StopTimeUpdate (in TripUpdate )	stop_time_properties	Proto
message TripUpdate	trip_properties	Proto
message TripUpdate	vehicle	VehicleDescriptor
message VehicleDescriptor	license_plate	String
message VehicleDescriptor	wheelchair_accessible	WheelchairAccessible
message VehiclePosition	congestion_level	Enum
message VehiclePosition	current_status	VehicleStopStatus
message VehiclePosition	current_stop_sequence	uint32
message VehiclePosition	multi_carriage_details.id	String
message VehiclePosition	occupancy_percentage	uint32
message VehiclePosition	stop_id	String

Different interpretation in the realtime feeds

Although Transit accepts certain GTFS fields, Transit interprets them differently than the GTFS.

Table 2 lists GTFS-defined fields in the realtime feeds that are either optional or required conditionally by Transit. For optional fields, the table shows whether or not the enum values are supported by Transit.

Experimental support in realtime feeds

If you need support to integrate new experimental fields, contact Google Transit .

Google Transit-supported extensions in realtime feeds

At the time of publishing this article, no fields belong to this category. If you need any assistance, contact Google Transit .