A set of values used to specify the mode of travel. NOTE: `WALK`, `BICYCLE`, and `TWO_WHEELER` routes are in beta and might sometimes be missing clear sidewalks, pedestrian paths, or bicycling paths. You must display this warning to the user for all walking, bicycling, and two-wheel routes that you display in your app.

| Enums ||
|---|---|
| `TRAVEL_MODE_UNSPECIFIED` | No travel mode specified. Defaults to `DRIVE`. |
| `DRIVE` | Travel by passenger car. |
| `BICYCLE` | Travel by bicycle. |
| `WALK` | Travel by walking. |
| `TWO_WHEELER` | Two-wheeled, motorized vehicle. For example, motorcycle. Note that this differs from the `BICYCLE` travel mode which covers human-powered mode. |
| `TRUCK` | Truck, which might be subject to regulatory or physical restrictions. You must populate vehicle attributes in the `https://developers.google.com/maps/documentation/routes/reference/rest/v2/RouteModifiers#VehicleInfo` message. |
| `TRANSIT` | Travel by public transit routes, where available. |