Avoid u-turns at pickup and delivery locations

By default, vehicles can arrive at a pickup or a delivery location from any direction, and then leave in any direction. In some cases, this forces the vehicle to make a u-turn at the visit location, which may be difficult or impossible because of vehicle size, traffic signs at the location, or usual traffic conditions.

To prevent vehicles from changing direction between the arrival and departure for a given pickup or delivery location, you can set avoid_u_turns to true for this location. Under this setting, the vehicle will arrive and leave the location with the same heading, thus avoiding the u-turn. On two-way roads the solver will consider both directions and choose one as part of the route optimization.

You can also set side_of_road to true to obtain a route where the vehicle arrives and leaves on the side of the road closest to the waypoint. In this case, the vehicle also does not change heading between the arrival and the departure. It is possible to set both side_of_road and avoid_u_turns to true to achieve the same result. For details, see Interaction with other features.

In practice, avoid_u_turns should be used when it is safe to cross the road to get to the waypoint. Use side_of_road when crossing is discouraged or not possible.

Example: Make an OptimizeTours request with avoid_u_turns

OptimizeTours requests can be made using either REST or gRPC.

Before making a request, replace the following parameters with values appropriate for your environment:

  • Ensure you have Application Default Credentials configured as described in Use OAuth.

  • Set PROJECT_NUMBER_OR_ID to your Cloud project number or ID.

    The following command sends an OptimizeTours request to the Route Optimization API and receives a response synchronously.

    curl -X POST 'https://routeoptimization.googleapis.com/v1/projects/PROJECT_NUMBER_OR_ID:optimizeTours' \
-H "Content-Type: application/json" \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
--data @- <<EOM
{
  "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
      }
    ],
  }
}
EOM

Once the request completes, you'll receive a response message.

Interaction with other features

  • avoid_u_turns can be used together with side_of_road = true. In this case, u-turns are avoided, but the solver selects a route that the vehicle is on the same side of the road as the waypoint, similar to setting side_of_road = true alone.
  • When avoid_u_turns = true for a certain visit request, then the ShipmentRoute.Visit in the corresponding response has the field injected_solution_location_token set. The precise meaning of its value is an implementation detail, but it encodes the information about the side of the road picked by the solver.
  • When you use a ShipmentRoute.Visit as part of the input request, if that ShipmentRoute.Visit corresponds to a VisitRequest in which avoid_u_turns = true, then ShipmentRoute.Visit must contain an injected_solution_location_token previously returned by the solver.

Limitations

U-turn avoidance is best effort. In certain situations, the route may still contain u-turns:

  • avoid_u_turns works only with travel modes that support side_of_road. Specifically, it is not supported for the WALKING travel mode.
  • avoid_u_turns can't be used for pickups and deliveries where the arrival and departure are not the same.
  • When a pickup or a delivery is on a dead-end road, it is necessary to make a u-turn to leave the road.
  • The aim of this feature is avoiding u-turns at pickup and delivery locations. U-turns between waypoints are not avoided.
  • Very sharp turns to a different road are not considered u-turns, and they will generally not be avoided.

There are additional limitations while this feature is under development. We expect them to be lifted as the feature evolves.