To calculate the number of container terminal equipment the information on the annual cargo traffic distribution and the handling equipment productivity is required. The wrong calculations in the hourly tasks for operation or productivity can lead to the wrong decisions in the number of needed equipment, the impossibility to handle the growing cargo traffic. Therefore, it is necessary to pay a special attention to the methods of calculation and generation of the specified parameters. However, designing a new terminal or analyzing the activity of existing one the specialists do not consider some technical limitations of certain handling equipment that influence on its productivity. Particularly, the reduction in productivity of warehouse loading cranes at high filling of the stack is not taken into account. As the stack occupancy rate approaches one the number of permutations per container doubles, that is connected with impossibility to place containers on the tier designed for spreader movement. In this case an operator has to place some boxes on the top level of the stack and then put them back. The influence of the described technology on the productivity cannot be revealed by the traditional mathematical methods. To evaluate the impact of this parameter a simulation model of the warehouse loading crane operation is created. The model allows us to prove that the productivity decreases when reaching 90% of the warehouse's occupancy. The suggested method can be used to define the probability density function of handling equipment more correctly.