The Queueing UC is part of the Loading Use Case. Therefore, it takes place after the loading machine has read the current and maximum payload of the hauling machine. As there could be multiple hauling machines queueing up for one or more loading machines, this UC determines the queueing position of the hauling machines. Thereby, the loading machine assignes a QueuePriority-Number to each hauling machine. The hauling machines can determine their respective queue position accordingly. Once the QueuePriority of a hauling machine is set to 1 this Use Case ends and the Positioning Use Case starts. A sequence diagram of this UC interaction is depicted in Figure 3.
Figure 3 – Sequence diagram of the Queueing (Loading) Use Case