GTFS Realtime Reference v2

A GTFS Realtime feed lets transit agencies provide consumers with realtime information about disruptions to their service (stations closed, lines not operating, important delays, etc.) location of their vehicles, and expected arrival times.

Version 2.0 of the feed specification is discussed and documented on this site. Valid versions are "2.0", "1.0".

Term Definitions

Required

In GTFS-realtime v2.0 and higher, the Required column describes what fields must be provided by a producer in order for the transit data to be valid and make sense to a consuming application.

The following values are used in the Required field:

Required: This field must be provided by a GTFS-realtime feed producer.
Conditionally required: This field is required under certain conditions, which are outlined in the field Description. Outside of these conditions, the field is optional.
Optional: This field is optional and is not required to be implemented by producers. However, if the data is available in the underlying automatic vehicle location systems (e.g., VehiclePosition timestamp) it is recommended that producers provide these optional fields when possible.

Note that semantic requirements were not defined in GTFS-realtime version 1.0, and therefore feeds with gtfs_realtime_version of 1 may not meet these requirements (see the proposal for semantic requirements for details).

Cardinality

Cardinality represents the number of elements that may be provided for a particular field, with the following values:

One - A single one element may be provided for this field. This maps to the Protocol Buffer required and optional cardinalities.
Many - Many elements (0, 1, or more) may be provided for this field. This maps to the Protocol Buffer repeated cardinality.

Always reference the Required and Description fields to see when a field is required, conditionally required, or optional. Please reference gtfs-realtime.proto for Protocol Buffer cardinality.

Protocol Buffer data types

The following protocol buffer data types are used to describe feed elements:

message: Complex type
enum: List of fixed values

Experimental fields

Fields labeled as experimental are subject to change and not yet formally adopted into the specification. An experimental field may be formally adopted in the future.

Element Index

FeedMessage
- FeedHeader
  - Incrementality
- FeedEntity

Elements

message FeedMessage

The contents of a feed message. Each message in the stream is obtained as a response to an appropriate HTTP GET request. A realtime feed is always defined with relation to an existing GTFS feed. All the entity ids are resolved with respect to the GTFS feed.

Fields

Field Name	Type	Required	Cardinality	Description
header	FeedHeader	Required	One	Metadata about this feed and feed message.
entity	FeedEntity	Conditionally required	Many	Contents of the feed. If there is real-time information available for the transit system, this field must be provided. If this field is empty, consumers should assume there is no real-time information available for the system.

message FeedHeader

Metadata about a feed, included in feed messages.

Fields

Field Name	Type	Required	Cardinality	Description
gtfs_realtime_version	string	Required	One	Version of the feed specification. The current version is 2.0.
incrementality	Incrementality	Required	One
timestamp	uint64	Required	One	This timestamp identifies the moment when the content of this feed has been created (in server time). In POSIX time (i.e., number of seconds since January 1st 1970 00:00:00 UTC). To avoid time skew between systems producing and consuming realtime information it is strongly advised to derive timestamp from a time server. It is completely acceptable to use Stratum 3 or even lower strata servers since time differences up to a couple of seconds are tolerable.

enum Incrementality

Determines whether the current fetch is incremental.

FULL_DATASET: this feed update will overwrite all preceding realtime information for the feed. Thus this update is expected to provide a full snapshot of all known realtime information.
DIFFERENTIAL: currently, this mode is unsupported and behavior is unspecified for feeds that use this mode. There are discussions on the GTFS Realtime mailing list around fully specifying the behavior of DIFFERENTIAL mode and the documentation will be updated when those discussions are finalized.

Values

Value
FULL_DATASET
DIFFERENTIAL

message FeedEntity

A definition (or update) of an entity in the transit feed. If the entity is not being deleted, exactly one of 'trip_update', 'vehicle' and 'alert' fields should be populated.

Fields

Field Name	Type	Required	Cardinality	Description
id	string	Required	One	Feed-unique identifier for this entity. The ids are used only to provide incrementality support. The actual entities referenced by the feed must be specified by explicit selectors (see EntitySelector below for more info).
is_deleted	bool	Optional	One	Whether this entity is to be deleted. Should be provided only for feeds with Incrementality of DIFFERENTIAL - this field should NOT be provided for feeds with Incrementality of FULL_DATASET.
trip_update	TripUpdate	Conditionally required	One	Data about the realtime departure delays of a trip. At least one of the fields trip_update, vehicle, or alert must be provided - all these fields cannot be empty.
vehicle	VehiclePosition	Conditionally required	One	Data about the realtime position of a vehicle. At least one of the fields trip_update, vehicle, or alert must be provided - all these fields cannot be empty.
alert	Alert	Conditionally required	One	Data about the realtime alert. At least one of the fields trip_update, vehicle, or alert must be provided - all these fields cannot be empty.

message TripUpdate

Realtime update on the progress of a vehicle along a trip. Please also refer to the general discussion of the trip updates entities.

Depending on the value of ScheduleRelationship, a TripUpdate can specify:

A trip that proceeds along the schedule.
A trip that proceeds along a route but has no fixed schedule.
A trip that has been added or removed with regard to schedule.

The updates can be for future, predicted arrival/departure events, or for past events that already occurred. In most cases information about past events is a measured value thus its uncertainty value is recommended to be 0. Although there could be cases when this does not hold so it is allowed to have uncertainty value different from 0 for past events. If an update's uncertainty is not 0, either the update is an approximate prediction for a trip that has not completed or the measurement is not precise or the update was a prediction for the past that has not been verified after the event occurred.

If a vehicle is serving multiple trips within the same block (for more information about trips and blocks, please refer to GTFS trips.txt):

the feed should include a TripUpdate for the trip currently being served by the vehicle. Producers are encouraged to include TripUpdates for one or more trips after the current trip in this vehicle's block if the producer is confident in the quality of the predictions for these future trip(s). Including multiple TripUpdates for the same vehicle avoids prediction "pop-in" for riders as the vehicle transitions from one trip to another and also gives riders advance notice of delays that impact downstream trips (e.g., when the known delay exceeds planned layover times between trips).
the respective TripUpdate entities are not required to be added to the feed in the same order that they are scheduled in the block. For example, if there are trips with trip_ids 1, 2, and 3 that all belong to one block, and the vehicle travels trip 1, then trip 2, and then trip 3, the trip_update entities may appear in any order - for example, adding trip 2, then trip 1, and then trip 3 is allowed.

Note that the update can describe a trip that has already completed.To this end, it is enough to provide an update for the last stop of the trip. If the time of arrival at the last stop is in the past, the client will conclude that the whole trip is in the past (it is possible, although inconsequential, to also provide updates for preceding stops). This option is most relevant for a trip that has completed ahead of schedule, but according to the schedule, the trip is still proceeding at the current time. Removing the updates for this trip could make the client assume that the trip is still proceeding. Note that the feed provider is allowed, but not required, to purge past updates - this is one case where this would be practically useful.

Fields

Field Name	Type	Required	Cardinality	Description
trip	TripDescriptor	Required	One	The Trip that this message applies to. There can be at most one TripUpdate entity for each actual trip instance. If there is none, that means there is no prediction information available. It does not mean that the trip is progressing according to schedule.
vehicle	VehicleDescriptor	Optional	One	Additional information on the vehicle that is serving this trip.
stop_time_update	StopTimeUpdate	Conditionally required	Many	Updates to StopTimes for the trip (both future, i.e., predictions, and in some cases, past ones, i.e., those that already happened). The updates must be sorted by stop_sequence, and apply for all the following stops of the trip up to the next specified stop_time_update. At least one stop_time_update must be provided for the trip unless the trip.schedule_relationship is CANCELED - if the trip is canceled, no stop_time_updates need to be provided.
timestamp	uint64	Optional	One	Moment at which the vehicle's real-time progress was measured. In POSIX time (i.e., the number of seconds since January 1st 1970 00:00:00 UTC).
delay	int32	Optional	One	The current schedule deviation for the trip. Delay should only be specified when the prediction is given relative to some existing schedule in GTFS. Delay (in seconds) can be positive (meaning that the vehicle is late) or negative (meaning that the vehicle is ahead of schedule). Delay of 0 means that the vehicle is exactly on time. Delay information in StopTimeUpdates take precedent of trip-level delay information, such that trip-level delay is only propagated until the next stop along the trip with a StopTimeUpdate delay value specified. Feed providers are strongly encouraged to provide a TripUpdate.timestamp value indicating when the delay value was last updated, in order to evaluate the freshness of the data. Caution: this field is still experimental, and subject to change. It may be formally adopted in the future.

message StopTimeEvent

Timing information for a single predicted event (either arrival or departure). Timing consists of delay and/or estimated time, and uncertainty.

delay should be used when the prediction is given relative to some existing schedule in GTFS.
time should be given whether there is a predicted schedule or not. If both time and delay are specified, time will take precedence (although normally, time, if given for a scheduled trip, should be equal to scheduled time in GTFS + delay).

Uncertainty applies equally to both time and delay. The uncertainty roughly specifies the expected error in true delay (but note, we don't yet define its precise statistical meaning). It's possible for the uncertainty to be 0, for example for trains that are driven under computer timing control.

Fields

Field Name	Type	Required	Cardinality	Description
delay	int32	Conditionally required	One	Delay (in seconds) can be positive (meaning that the vehicle is late) or negative (meaning that the vehicle is ahead of schedule). Delay of 0 means that the vehicle is exactly on time. Either delay or time must be provided within a StopTimeEvent - both fields cannot be empty.
time	int64	Conditionally required	One	Event as absolute time. In POSIX time (i.e., number of seconds since January 1st 1970 00:00:00 UTC). Either delay or time must be provided within a StopTimeEvent - both fields cannot be empty.
uncertainty	int32	Optional	One	If uncertainty is omitted, it is interpreted as unknown. To specify a completely certain prediction, set its uncertainty to 0.

message StopTimeUpdate

Realtime update for arrival and/or departure events for a given stop on a trip. Please also refer to the general discussion of stop time updates in the TripDescriptor and trip updates entities documentation.

Updates can be supplied for both past and future events. The producer is allowed, although not required, to drop past events. The update is linked to a specific stop either through stop_sequence or stop_id, so one of these fields must necessarily be set. If the same stop_id is visited more than once in a trip, then stop_sequence should be provided in all StopTimeUpdates for that stop_id on that trip.

Fields

Field Name	Type	Required	Cardinality	Description
stop_sequence	uint32	Conditionally required	One	Must be the same as in stop_times.txt in the corresponding GTFS feed. Either stop_sequence or stop_id must be provided within a StopTimeUpdate - both fields cannot be empty. stop_sequence is required for trips that visit the same stop_id more than once (e.g., a loop) to disambiguate which stop the prediction is for.
stop_id	string	Conditionally required	One	Must be the same as in stops.txt in the corresponding GTFS feed. Either stop_sequence or stop_id must be provided within a StopTimeUpdate - both fields cannot be empty.
arrival	StopTimeEvent	Conditionally required	One	If schedule_relationship is empty or SCHEDULED, either arrival or departure must be provided within a StopTimeUpdate - both fields cannot be empty. arrival and departure may both be empty when schedule_relationship is SKIPPED. If schedule_relationship is NO_DATA, arrival and departure must be empty.
departure	StopTimeEvent	Conditionally required	One	If schedule_relationship is empty or SCHEDULED, either arrival or departure must be provided within a StopTimeUpdate - both fields cannot be empty. arrival and departure may both be empty when schedule_relationship is SKIPPED. If schedule_relationship is NO_DATA, arrival and departure must be empty.
schedule_relationship	ScheduleRelationship	Optional	One	The default relationship is SCHEDULED.

enum ScheduleRelationship

The relation between this StopTime and the static schedule.

Values

Value	Comment
SCHEDULED	The vehicle is proceeding in accordance with its static schedule of stops, although not necessarily according to the times of the schedule. This is the default behavior. At least one of arrival and departure must be provided. Frequency-based trips (GTFS frequencies.txt with exact_times = 0) should not have a SCHEDULED value and should use UNSCHEDULED instead.
SKIPPED	The stop is skipped, i.e., the vehicle will not stop at this stop. Arrival and departure are optional. When set `SKIPPED` is not propagated to subsequent stops in the same trip (i.e., the vehicle will stop at subsequent stops in the trip unless those stops also have a `stop_time_update` with `schedule_relationship: SKIPPED`). Delay from a previous stop in the trip does propagate over the `SKIPPED` stop. In other words, if a `stop_time_update` with an `arrival` or `departure` prediction is not set for a stop after the `SKIPPED` stop, the prediction upstream of the `SKIPPED` stop will be propagated to the stop after the `SKIPPED` stop and subsequent stops in the trip until a `stop_time_update` for a subsequent stop is provided.
NO_DATA	No data is given for this stop. It indicates that there is no realtime information available. When set NO_DATA is propagated through subsequent stops so this is the recommended way of specifying from which stop you do not have realtime information. When NO_DATA is set neither arrival nor departure should be supplied.
UNSCHEDULED	The vehicle is operating a frequency-based trip (GTFS frequencies.txt with exact_times = 0). This value should not be used for trips that are not defined in GTFS frequencies.txt, or trips in GTFS frequencies.txt with exact_times = 1. Trips containing `stop_time_updates` with `schedule_relationship: UNSCHEDULED` must also set the TripDescriptor `schedule_relationship: UNSCHEDULED` Caution: this field is still experimental, and subject to change. It may be formally adopted in the future. .

message VehiclePosition

Realtime positioning information for a given vehicle.

Fields

Field Name	Type	Required	Cardinality	Description
trip	TripDescriptor	Optional	One	The Trip that this vehicle is serving. Can be empty or partial if the vehicle can not be identified with a given trip instance.
vehicle	VehicleDescriptor	Optional	One	Additional information on the vehicle that is serving this trip. Each entry should have a unique vehicle id.
position	Position	Optional	One	Current position of this vehicle.
current_stop_sequence	uint32	Optional	One	The stop sequence index of the current stop. The meaning of current_stop_sequence (i.e., the stop that it refers to) is determined by current_status. If current_status is missing IN_TRANSIT_TO is assumed.
stop_id	string	Optional	One	Identifies the current stop. The value must be the same as in stops.txt in the corresponding GTFS feed.
current_status	VehicleStopStatus	Optional	One	The exact status of the vehicle with respect to the current stop. Ignored if current_stop_sequence is missing.
timestamp	uint64	Optional	One	Moment at which the vehicle's position was measured. In POSIX time (i.e., number of seconds since January 1st 1970 00:00:00 UTC).
congestion_level	CongestionLevel	Optional	One
occupancy_status	OccupancyStatus	Optional	One	The degree of passenger occupancy of the vehicle. Caution: this field is still experimental, and subject to change. It may be formally adopted in the future.
occupancy_percentage	uint32	Optional	One	A percentage value representing the degree of passenger occupancy of the vehicle. The value 100 should represent total the maximum occupancy the vehicle was designed for, including both seating and standing capacity, and current operating regulations allow. It's not impossible that the value goes over 100 if there are currently more passenger than the vehicle was designed for. The precision of precision should be low enough that you can't track a single person boarding and alighting for privacy reasons. Caution: this field is still experimental, and subject to change. It may be formally adopted in the future.

enum VehicleStopStatus

Values

Value	Comment
INCOMING_AT	The vehicle is just about to arrive at the stop (on a stop display, the vehicle symbol typically flashes).
STOPPED_AT	The vehicle is standing at the stop.
IN_TRANSIT_TO	The vehicle has departed the previous stop and is in transit.

enum CongestionLevel

Congestion level that is affecting this vehicle.

Values

Value
UNKNOWN_CONGESTION_LEVEL
RUNNING_SMOOTHLY
STOP_AND_GO
CONGESTION
SEVERE_CONGESTION

enum OccupancyStatus

The degree of passenger occupancy for the vehicle.

Caution: this field is still experimental, and subject to change. It may be formally adopted in the future.

Values

Value	Comment
EMPTY	The vehicle is considered empty by most measures, and has few or no passengers onboard, but is still accepting passengers.
MANY_SEATS_AVAILABLE	The vehicle has a large percentage of seats available. What percentage of free seats out of the total seats available is to be considered large enough to fall into this category is determined at the discretion of the producer.
FEW_SEATS_AVAILABLE	The vehicle has a small percentage of seats available. What percentage of free seats out of the total seats available is to be considered small enough to fall into this category is determined at the discretion of the producer.
STANDING_ROOM_ONLY	The vehicle can currently accommodate only standing passengers.
CRUSHED_STANDING_ROOM_ONLY	The vehicle can currently accommodate only standing passengers and has limited space for them.
FULL	The vehicle is considered full by most measures, but may still be allowing passengers to board.
NOT_ACCEPTING_PASSENGERS	The vehicle can not accept passengers.

message Alert

An alert, indicating some sort of incident in the public transit network.

Fields

Field Name	Type	Required	Cardinality	Description
active_period	TimeRange	Optional	Many	Time when the alert should be shown to the user. If missing, the alert will be shown as long as it appears in the feed. If multiple ranges are given, the alert will be shown during all of them.
informed_entity	EntitySelector	Required	Many	Entities whose users we should notify of this alert. At least one informed_entity must be provided.
cause	Cause	Optional	One
effect	Effect	Optional	One
url	TranslatedString	Optional	One	The URL which provides additional information about the alert.
header_text	TranslatedString	Required	One	Header for the alert. This plain-text string will be highlighted, for example in boldface.
description_text	TranslatedString	Required	One	Description for the alert. This plain-text string will be formatted as the body of the alert (or shown on an explicit "expand" request by the user). The information in the description should add to the information of the header.
tts_header_text	TranslatedString	Optional	One	Text containing the alert's header to be used for text-to-speech implementations. This field is the text-to-speech version of header_text. It should contain the same information as header_text but formatted such that it can read as text-to-speech (for example, abbreviations removed, numbers spelled out, etc.) Caution: this field is still experimental, and subject to change. It may be formally adopted in the future.
tts_description_text	TranslatedString	Optional	One	Text containing a description for the alert to be used for text-to-speech implementations. This field is the text-to-speech version of description_text. It should contain the same information as description_text but formatted such that it can be read as text-to-speech (for example, abbreviations removed, numbers spelled out, etc.) Caution: this field is still experimental, and subject to change. It may be formally adopted in the future.
severity_level	SeverityLevel	Optional	One	Severity of the alert.

enum Cause

Cause of this alert.

Values

Value
UNKNOWN_CAUSE
OTHER_CAUSE
TECHNICAL_PROBLEM
STRIKE
DEMONSTRATION
ACCIDENT
HOLIDAY
WEATHER
MAINTENANCE
CONSTRUCTION
POLICE_ACTIVITY
MEDICAL_EMERGENCY

enum Effect

The effect of this problem on the affected entity.

Values

Value
NO_SERVICE
REDUCED_SERVICE
SIGNIFICANT_DELAYS
DETOUR
ADDITIONAL_SERVICE
MODIFIED_SERVICE
OTHER_EFFECT
UNKNOWN_EFFECT
STOP_MOVED
NO_EFFECT
ACCESSIBILITY_ISSUE

enum SeverityLevel

The severity of the alert.

Caution: this field is still experimental, and subject to change. It may be formally adopted in the future.

Values

Value
UNKNOWN_SEVERITY
INFO
WARNING
SEVERE

message TimeRange

A time interval. The interval is considered active at time t if t is greater than or equal to the start time and less than the end time.

Fields

Field Name	Type	Required	Cardinality	Description
start	uint64	Conditionally required	One	Start time, in POSIX time (i.e., number of seconds since January 1st 1970 00:00:00 UTC). If missing, the interval starts at minus infinity. If a TimeRange is provided, either start or end must be provided - both fields cannot be empty.
end	uint64	Conditionally required	One	End time, in POSIX time (i.e., number of seconds since January 1st 1970 00:00:00 UTC). If missing, the interval ends at plus infinity. If a TimeRange is provided, either start or end must be provided - both fields cannot be empty.

message Position

A geographic position of a vehicle.

Fields

Field Name	Type	Required	Cardinality	Description
latitude	float	Required	One	Degrees North, in the WGS-84 coordinate system.
longitude	float	Required	One	Degrees East, in the WGS-84 coordinate system.
bearing	float	Optional	One	Bearing, in degrees, clockwise from True North, i.e., 0 is North and 90 is East. This can be the compass bearing, or the direction towards the next stop or intermediate location. This should not be deduced from the sequence of previous positions, which clients can compute from previous data.
odometer	double	Optional	One	Odometer value, in meters.
speed	float	Optional	One	Momentary speed measured by the vehicle, in meters per second.

message TripDescriptor

A descriptor that identifies a single instance of a GTFS trip.

To specify a single trip instance, in many cases a trip_id by itself is sufficient. However, the following cases require additional information to resolve to a single trip instance:

For trips defined in frequencies.txt, start_date and start_time are required in addition to trip_id
If the trip lasts for more than 24 hours, or is delayed such that it would collide with a scheduled trip on the following day, then start_date is required in addition to trip_id
If the trip_id field can't be provided, then route_id, direction_id, start_date, and start_time must all be provided

In all cases, if route_id is provided in addition to trip_id, then the route_id must be the same route_id as assigned to the given trip in GTFS trips.txt.

The trip_id field cannot, by itself or in combination with other TripDescriptor fields, be used to identify multiple trip instances. For example, a TripDescriptor should never specify trip_id by itself for GTFS frequencies.txt exact_times=0 trips because start_time is also required to resolve to a single trip instance starting at a specific time of the day. If the TripDescriptor does not resolve to a single trip instance (i.e., it resolves to zero or multiple trip instances), it is considered an error and the entity containing the erroneous TripDescriptor may be discarded by consumers.

Note that if the trip_id is not known, then station sequence ids in TripUpdate are not sufficient, and stop_ids must be provided as well. In addition, absolute arrival/departure times must be provided.

TripDescriptor.route_id cannot be used within an Alert EntitySelector to specify a route-wide alert that affects all trips for a route - use EntitySelector.route_id instead.

Fields

Field Name	Type	Required	Cardinality	Description
trip_id	string	Conditionally required	One	The trip_id from the GTFS feed that this selector refers to. For non frequency-based trips (trips not defined in GTFS frequencies.txt), this field is enough to uniquely identify the trip. For frequency-based trips defined in GTFS frequencies.txt, trip_id, start_time, and start_date are all required. For scheduled-based trips (trips not defined in GTFS frequencies.txt), trip_id can only be omitted if the trip can be uniquely identified by a combination of route_id, direction_id, start_time, and start_date, and all those fields are provided.
route_id	string	Conditionally required	One	The route_id from the GTFS that this selector refers to. If trip_id is omitted, route_id, direction_id, start_time, and schedule_relationship=SCHEDULED must all be set to identify a trip instance. TripDescriptor.route_id should not be used within an Alert EntitySelector to specify a route-wide alert that affects all trips for a route - use EntitySelector.route_id instead.
direction_id	uint32	Conditionally required	One	The direction_id from the GTFS feed trips.txt file, indicating the direction of travel for trips this selector refers to. If trip_id is omitted, direction_id must be provided. Caution: this field is still experimental, and subject to change. It may be formally adopted in the future.
start_time	string	Conditionally required	One	The initially scheduled start time of this trip instance. When the trip_id corresponds to a non-frequency-based trip, this field should either be omitted or be equal to the value in the GTFS feed. When the trip_id correponds to a frequency-based trip defined in GTFS frequencies.txt, start_time is required and must be specified for trip updates and vehicle positions. If the trip corresponds to exact_times=1 GTFS record, then start_time must be some multiple (including zero) of headway_secs later than frequencies.txt start_time for the corresponding time period. If the trip corresponds to exact_times=0, then its start_time may be arbitrary, and is initially expected to be the first departure of the trip. Once established, the start_time of this frequency-based exact_times=0 trip should be considered immutable, even if the first departure time changes -- that time change may instead be reflected in a StopTimeUpdate. If trip_id is omitted, start_time must be provided. Format and semantics of the field is same as that of GTFS/frequencies.txt/start_time, e.g., 11:15:35 or 25:15:35.
start_date	string	Conditionally required	One	The start date of this trip instance in YYYYMMDD format. For scheduled trips (trips not defined in GTFS frequencies.txt), this field must be provided to disambiguate trips that are so late as to collide with a scheduled trip on a next day. For example, for a train that departs 8:00 and 20:00 every day, and is 12 hours late, there would be two distinct trips on the same time. This field can be provided but is not mandatory for schedules in which such collisions are impossible - for example, a service running on hourly schedule where a vehicle that is one hour late is not considered to be related to schedule anymore. This field is required for frequency-based trips defined in GTFS frequencies.txt. If trip_id is omitted, start_date must be provided.
schedule_relationship	ScheduleRelationship	Optional	One	The relation between this trip and the static schedule. If TripDescriptor is provided in an Alert `EntitySelector`, the `schedule_relationship` field is ignored by consumers when identifying the matching trip instance.

enum ScheduleRelationship

The relation between this trip and the static schedule. If a trip is done in accordance with temporary schedule, not reflected in GTFS, then it shouldn't be marked as SCHEDULED, but marked as ADDED.

Values

Value	Comment
SCHEDULED	Trip that is running in accordance with its GTFS schedule, or is close enough to the scheduled trip to be associated with it.
ADDED	An extra trip that was added in addition to a running schedule, for example, to replace a broken vehicle or to respond to sudden passenger load.
UNSCHEDULED	A trip that is running with no schedule associated to it - this value is used to identify trips defined in GTFS frequencies.txt with exact_times = 0. It should not be used to describe trips not defined in GTFS frequencies.txt, or trips in GTFS frequencies.txt with exact_times = 1. Trips with `schedule_relationship: UNSCHEDULED` must also set all StopTimeUpdates `schedule_relationship: UNSCHEDULED`
CANCELED	A trip that existed in the schedule but was removed.

message VehicleDescriptor

Identification information for the vehicle performing the trip.

Fields

Field Name	Type	Required	Cardinality	Description
id	string	Optional	One	Internal system identification of the vehicle. Should be unique per vehicle, and is used for tracking the vehicle as it proceeds through the system. This id should not be made visible to the end-user; for that purpose use the label field
label	string	Optional	One	User visible label, i.e., something that must be shown to the passenger to help identify the correct vehicle.
license_plate	string	Optional	One	The license plate of the vehicle.

message EntitySelector

A selector for an entity in a GTFS feed. The values of the fields should correspond to the appropriate fields in the GTFS feed. At least one specifier must be given. If several are given, they should be interpreted as being joined by the logical AND operator. Additionally, the combination of specifiers must match the corresponding information in the GTFS feed. In other words, in order for an alert to apply to an entity in GTFS it must match all of the provided EntitySelector fields. For example, an EntitySelector that includes the fields route_id: "5" and route_type: "3" applies only to the route_id: "5" bus - it does not apply to any other routes of route_type: "3". If a producer wants an alert to apply to route_id: "5" as well as route_type: "3", it should provide two separate EntitySelectors, one referencing route_id: "5" and another referencing route_type: "3".

At least one specifier must be given - all fields in an EntitySelector cannot be empty.

Fields

Field Name	Type	Required	Cardinality	Description
agency_id	string	Conditionally required	One	The agency_id from the GTFS feed that this selector refers to.
route_id	string	Conditionally required	One	The route_id from the GTFS that this selector refers to. If direction_id is provided, route_id must also be provided.
route_type	int32	Conditionally required	One	The route_type from the GTFS that this selector refers to.
direction_id	uint32	Conditionally required	One	The direction_id from the GTFS feed trips.txt file, used to select all trips in one direction for a route, specified by route_id. If direction_id is provided, route_id must also be provided. Caution: this field is still experimental, and subject to change. It may be formally adopted in the future.
trip	TripDescriptor	Conditionally required	One	The trip instance from the GTFS that this selector refers to. This TripDescriptor must resolve to a single trip instance in the GTFS data (e.g., a producer cannot provide only a trip_id for exact_times=0 trips). If the ScheduleRelationship field is populated within this TripDescriptor it will be ignored by consumers when attempting to identify the GTFS trip.
stop_id	string	Conditionally required	One	The stop_id from the GTFS feed that this selector refers to.

message TranslatedString

An internationalized message containing per-language versions of a snippet of text or a URL. One of the strings from a message will be picked up. The resolution proceeds as follows: If the UI language matches the language code of a translation, the first matching translation is picked. If a default UI language (e.g., English) matches the language code of a translation, the first matching translation is picked. If some translation has an unspecified language code, that translation is picked.

Fields

Field Name	Type	Required	Cardinality	Description
translation	Translation	Required	Many	At least one translation must be provided.

message Translation

A localized string mapped to a language.

Fields

Field Name	Type	Required	Cardinality	Description
text	string	Required	One	A UTF-8 string containing the message.
language	string	Conditionally required	One	BCP-47 language code. Can be omitted if the language is unknown or if no internationalization is done at all for the feed. At most one translation is allowed to have an unspecified language tag - if there is more than one translation, the language must be provided.