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 U-turn avoidance is a route optimization feature that prevents vehicles from turning around at the specific pickup or delivery location of a visit. By setting u-turn avoidance, you specify that the vehicle should face the same direction when it arrives and when it leaves a visit location. U-turn avoidance works in the following way: 1. You set the u-turn avoidance property on a specific visit. 2. The API considers both directions of travel on two-way roads and chooses the most optimal path. 3. The API generates a route where the vehicle arrives and leaves without making a u-turn at the visit location. The driver may need to cross the road to reach this location. This property is ideal for situations where making a u-turn is difficult or impossible due to vehicle size, traffic signs, or usual traffic conditions. ## Properties The u-turn avoidance property is defined within the [`VisitRequest`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#VisitRequest) object. This object is used inside the [`pickups`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#Shipment.FIELDS.pickups) and [`deliveries`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#Shipment.FIELDS.deliveries) arrays of a shipment. | Property | Type | Description | |---|---|---| | [`avoidUTurns`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#VisitRequest.FIELDS.avoid_u_turns) | boolean | When set to `true`, the API prevents the vehicle from making a u-turn at this visit location. The vehicle will arrive and leave facing the same direction. | ## Examples This section covers two types of examples: - Code samples that illustrate the structure of u-turn avoidance. - A request example that includes the feature. ### Code samples The following example shows the structure of[`avoidUTurns`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#VisitRequest.FIELDS.avoid_u_turns) within a pickup and a delivery: ```json "pickups":[ { "arrivalLocation": { "latitude": 37.42506261000996, "longitude": -122.09535511930135 }, "avoidUTurns": true } ], "deliveries":[ { "arrivalLocation": { "latitude": 37.42421503206021, "longitude": -122.09526063135228 }, "avoidUTurns": true } ] ``` ### Request example The following example shows a basic [`optimizeTours`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/projects/optimizeTours.md.txt) request that incorporates u-turn avoidance. This request includes the following elements: - A shipment with a pickup and a delivery inside the `model` object. - The [`avoidUTurns`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#VisitRequest.FIELDS.avoid_u_turns) property set to `true` on both the pickup and delivery locations to prevent the vehicle from changing direction at those stops. ```json { "model": { "shipments":[ { "pickups":[ { "arrivalLocation": { "latitude": 37.42506261000996, "longitude": -122.09535511930135 }, "avoidUTurns": true } ], "deliveries":[ { "arrivalLocation": { "latitude": 37.42421503206021, "longitude": -122.09526063135228 }, "avoidUTurns": true } ] } ], "vehicles":[ { "travelMode": "DRIVING", "costPerKilometer": 1.0 } ] } } ``` ## Avoid u-turns with `sideOfRoad` While [`sideOfRoad`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#Waypoint.FIELDS.side_of_road) is a separate feature, it is closely related to u-turn avoidance because it prevents many u-turns by routing the vehicle to the side of the road closest to the destination. This forces the vehicle to approach a visit location from a specific direction, which eliminates the need to do a u-turn. In practice, you should use u-turn avoidance when it is safe to cross the road on foot to get to the visit location. If crossing the road is discouraged or not possible, consider setting [`sideOfRoad`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#Waypoint.FIELDS.side_of_road) to `true` instead. The [`sideOfRoad`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#Waypoint.FIELDS.side_of_road) property is defined within a [`Waypoint`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#Waypoint) object. ## Interaction with other features U-turn avoidance interacts with other routing features in the following ways: - **Side of road:** Setting both [`avoidUTurns`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#VisitRequest.FIELDS.avoid_u_turns) and [`sideOfRoad`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentModel.md.txt#Waypoint.FIELDS.side_of_road) to `true` slightly increases the chances of avoiding a u-turn while routing the vehicle to the side of the road closest to the visit location. However, doing so introduces extra complexities related to the restrictions of u-turn avoidance. For most visit locations, setting only one of these properties is enough to avoid u-turns. - **Injected solutions:** When you use u-turn avoidance, the API response includes an [`injectedSolutionLocationToken`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentRoute.md.txt#Visit.FIELDS.injected_solution_location_token) inside the generated [`ShipmentRoute.Visit`](https://developers.google.com/maps/tt/route-optimization/experimental/u-turn-avoidance/reference/rest/v1/ShipmentRoute.md.txt#Visit) to record which side of the road it selected. If you ever reuse this visit as an injected solution in a future request, you must pass this token back to the API. ## Limitations U-turn avoidance is a best-effort feature. The API might still include u-turns in a generated route under the following conditions: - The travel mode is set to a mode other than `DRIVING`. - The arrival and departure locations for a specific visit location are different. In this case, the API returns an error. - The visit is located on a dead-end road, requiring a u-turn to exit. - The u-turn occurs along the route, rather than at the actual visit location. - The maneuver is a very sharp turn onto a different road, which the API does not classify as a u-turn.