## 2 Handling Loading Units in an Intermodal Handling Transshipment
### Assignment of a Storage Position and Container Translocation within a Terminal
In the context of research on assigning positions to freight units, the terms \"optimal\" or \"efficient\" action plan can be interpreted in various ways, specifically as  
* conducting work in a way that ensures the shortest possible operation time when handling freight units by equipment (including minimizing energy and fuel consumption, shortening operations to enable the handling of a larger number of units in a given time),
* shortening the handling time of units towards the vehicles,
* maximizing or evenly utilizing the surface of the storage yard (striving to even out the height of intermodal unit stacks, equalizing loading operation times),
* limiting the number of unproductive operations (modifying the execution of operations that may not result in the shortest handling of freight units during a single operation, but contribute to a shorter overall terminal working time). Terminal operations can be divided into those related to unloading, warehousing, equipment scheduling, gate handling, and railway forwarding, but none of these areas are treated separately. The authors do not consider how the effect of rationalizing actions in one area can complicate (or simplify) operations in the next stage of terminal handling. Issues of minimizing cargo handling energy expenditure are presented in publications [14; 17; 23; 28; 29; 30]. The main context of minimizing energy consumption of equipment is shown in [14; 18; 22; 35; 36; 37]. Increasing container terminal efficiency by limiting the number of manipulations is proposed in [14; 15; 18; 22; 24; 25; 26]. Container terminal efficiency understood as balancing workload is visible in [12; 15; 23; 36; 38; 39]. Ways to increase productivity by decreasing task lead time are presented in [14; 18; 22; 25; 32; 33; 34; 37; 40; 41] and by maximizing position utilization in publications [40; 41]. Most publications are related to the issue of ship or train unloading. Given the fact that unloading requires a large number of operations over a limited time, the basic problem addressed in the papers is minimizing unloading time. Some studies investigate minimizing the energy associated with allocating or unloading freight units. The first case refers to balancing consumed energy in the context of handling a greater number than several freight units. The second case concerns minimizing individual manipulations. The first approach should be treated as slightly more complex because the authors specify the possibility of manipulations that are not the most economic individually, but their sum leads to minimizing the total energy expenditure (however, only within the studied area). The authors of [41] noted that adopting other operational strategies when unloading freight units at a storage yard can lead to various effects in the form of different train handling times. Eliminating unproductive moves is an overlooked issue, which can be surprising in the context of striving for minimizing freight unit handling times or minimizing the energy that is required for all conducted operations. The issue appears in just a few publications; however, they manifest a strong assumption related to the knowledge of the freight unit release date. Conclusions Related to the Dependence between the Number of Occupied Positions and the Number of Unproductive Manipulations  
The concept of individual methods aimed at improving the operations of a container terminal has one fundamental flaw in the form of the lack of testing the total value of request streams to the handling system with the terminal transshipment capacity. It is worth employing simulation methods for this purpose. One of the interesting examples of employing simulation to reduce the number of unproductive manipulations was demonstrated in [42]. It was hypothesized that container allocation was a key factor impacting terminal operating effectiveness. The suggested model determines a possible freight operation sequence that minimizes costs associated with container storage.