An order is a request to either transport goods consisting of a pickup and a delivery task or provide a service at a specific location. The main goal of the optimization is to effectively schedule these tasks onto routes. We differentiate among four types of orders:
- Pickup orders — An order to collect goods from a designated location and transport them to a depot. The pickup task is specific to the order while the delivery task is partially (e.g. location id, time slots,...) determined by the depot, chosen by the optimization.
- Delivery orders — An order to transport goods from a depot and distribute them to a designated location. The delivery task is specific to the order while the pickup task is partially (e.g. location id, time slots,...) determined by the depot, chosen by the optimization.
- Pickup-delivery orders — An order to transport goods between designated locations. Both the pickup and delivery tasks are specific to the order and depots are irrelevant for this type of order.
- Service orders — An order to provide a service at a designated location. Depots, compartments and loading incompatibilities are irrelevant for service orders as they do not involve transport.
Loads
Not every order fits into every vehicle. The loads of an order specify its dimensions such as weight, volume or pallets. The optimization will make sure that the order combination loaded into the vehicle will not exceed the maximum loads of the vehicle for each dimension. Loads cannot be defined for service orders.
Repositioning effort
Defines the effort to reposition an order when it obstructs another order in a compartment. Obstruction occurs when two orders are picked up and delivered in the same order and, therefore, do not satisfy the last-in-first-out (LIFO) principle. In such a case, the orders will be repositioned by moving the order with the least defined effort. Repositioning may incur a cost when configured on a vehicle. As service orders are not loaded, repositioning effort cannot be defined for this type of orders.
Outsourcing cost
The outsourcing cost associated with an order indicates an additional expense in the event that the optimization does not incorporate the order into a route. The optimization will refrain from scheduling the order if the additional cost of including it in a route exceeds the outsourcing cost.
When omitted, the optimization will try to plan the order regardless of the cost. In this case, the order does not contribute to the cost when unscheduled.
Order categories
Certain constraints are not only specific to the order but entail different entities such as vehicles or depots. These constraints are typically expressed based on categories, which are often functional properties of the order itself. Examples of order categories might be whether an order requires to be cooled, contains hazardous goods or possesses any other essential property associated with the order.
Tasks
The scheduling of an order requires the scheduling of one or more tasks. Orders involving the transportation of goods consist of a pickup and a delivery task while service orders consist of a singular task. While certain order properties—like load or outsourcing cost—remain task-independent, other properties such as a location or available time slots are specific to tasks. For orders requiring a transportation of goods from or a to a depot, some properties can also be defined on the depots where these tasks can take place.
- A pickup order consists of a pickup and a delivery task. The pickup task defines information about the task executed at a specific location while the delivery task defines information about the task executed at any suitable depot.
- A delivery order consists of a pickup and a delivery task. The delivery task defines information about the task executed at a specific location while the pickup task defines information about the task executed at any suitable depot.
- A pickup-delivery order consists of a pickup and a delivery task. Both the pickup and the delivery task define information about tasks executed at specific locations. For these type of orders neither the pickup nor the delivery task is executed at a depot.
- A service order consists of a singular task, which defines information about the service performed at a specific location.
The tasks that are defined on order level include the following properties.
Location
Certain tasks are executed at a specific location. For tasks that occur at a depot, the location cannot be defined and is instead inferred from the selected depot.
Time slots
A location establishes time slots, determining when tasks can be scheduled for execution at that specific place. A task can further restrict which of these available time slots can be used for scheduling an appointment to execute the task. For depot tasks it is not possible to restrict the time slots of the depot.
Duration
The duration of the task defines how long it takes to be executed. This includes the time required for the service to be performed or the goods to be loaded or unloaded.
Task categories
While some constraints can be expressed with respect to the order, other constraints apply only to a specific task. Therefore, categories can be defined not only for orders, but also for their tasks. Such task categories are often functional properties of the task itself. Examples of task categories might indicate the region in which a task should be executed, a preferred position in the route or any other essential property associated with the task.