- [JSON representation](https://developers.google.com/maps/documentation/routes/reference/rest/v2/SpeedReadingInterval#SCHEMA_REPRESENTATION)
- [Speed](https://developers.google.com/maps/documentation/routes/reference/rest/v2/SpeedReadingInterval#Speed)

Traffic density indicator on a contiguous segment of a polyline or path. Given a path with points P_0, P_1, ... , P_N (zero-based index), the `SpeedReadingInterval` defines an interval and describes its traffic using the following categories.

| JSON representation |
|---|
| ``` { "startPolylinePointIndex": integer, "endPolylinePointIndex": integer, // The following is a list of mutually exclusive fields. At most one of the // fields will be set in a response: "speed": enum (`https://developers.google.com/maps/documentation/routes/reference/rest/v2/SpeedReadingInterval#Speed`) // End of mutually exclusive fields. } ``` |

| Fields ||
|---|---|
| `startPolylinePointIndex` | `integer` The starting index of this interval in the polyline. |
| `endPolylinePointIndex` | `integer` The ending index of this interval in the polyline. |
| The type of speed in this interval. The following is a list of mutually exclusive fields. At most one of the fields will be set in a response: ||
| `speed` | ``enum (`https://developers.google.com/maps/documentation/routes/reference/rest/v2/SpeedReadingInterval#Speed`)`` Traffic speed in this interval. |
| End of mutually exclusive fields. ||

## Speed

The classification of polyline speed based on traffic data.

| Enums ||
|---|---|
| `SPEED_UNSPECIFIED` | Default value. This value is unused. |
| `NORMAL` | Normal speed, no traffic delays. |
| `SLOW` | Slowdown detected, medium amount of traffic. |
| `TRAFFIC_JAM` | Traffic delays. |