Google Transit lets you use realtime data over General Transit Feed Specification (GTFS) static by adding vehicle positions data in your feed. Vehicle position provides Transit users with updates on the location of a vehicle, which lets users plan their trips more efficiently. This article lists the minimum requirements for a working feed of vehicle positions.
How vehicle position feeds work
Before you create a GTFS-realtime feed, you need to have a working GTFS static feed. After you’ve created a working GTFS static feed, you can sign up to share your reatime feed to show users your vehicle positions.
In order for vehicle positions to show accurate arrival and departure estimates, we require, at minimum, the list of fields shown below:
| Field name | Required? | Description |
entity |
Yes | (maps_transit.FeedEntity) |
entity_id |
Yes | Keep this stable until trip is updated |
vehicle (position) |
Yes | (maps_transit.VehiclePosition) |
trip |
Yes | (maps_transit.TripDescriptor) |
trip_id |
Yes | Uniquely identifies a trip from the static |
start_time |
Yes | Required for frequency-based trips |
start_date |
Yes | Required for frequency-based trips |
schedule_relationship |
Yes | SCHEDULED or other appropriate |
position |
Yes | (maps_transit.Position) |
latitude |
Yes | Degrees north in the WGS-84 coordinate system |
longitude |
Yes | Degrees east in the WGS-84 coordinate system |
bearing |
Optional | Might be used in the future |
speed |
Optional | Might be used in the future |
timestamp |
Yes | Epoch timestamp of when the position of the vehicle was obtained in seconds |
vehicle (descriptor) |
Yes | (maps_transit.VehicleDescriptor) |
id |
Yes | This must uniquely and stably identify a vehicle over the entire trip duration |
Example code
entity {
id: "entity_id"
vehicle: {
trip: {
trip_id: "270856"
start_time: "09:42:00"
start_date: "20170313"
schedule_relationship: SCHEDULED
}
position: {
latitude : -32.92627
longitude: 151.78036
bearing : 91.0
speed : 9.8
}
timestamp: 1527621931
vehicle: {
id : "bus-234"
}
}
}
For more details on trip descriptors, check out the TripDescriptors for TripUpdate and VehiclePosition article.