Evaluation of Sinking Effect in Container Stack

The container yard is the key element of any modern container terminal. The huge amount of boxes dwelling on the operational areas of the terminals could occupy a lot of space, since one-time storage capacity of the container mega terminal handling over one million TEUs annually is something around 20 000 TEUs. The ecological pressure imposed on modern container terminal does not permit to allocate for this storage large land areas, thus forcing the box stacks grow high. The selection of the individual boxes becomes a complex and time-consuming procedure, demanding a lot of technological resources and deteriorating the service quality. The predicted combinatorial growth of redundant moves needed to clear the access to the individual container is aggravated by the well-known and widely discussed ‘sinking effect’, when containers arrived earlier are gradually covered by the ones arriving afterwards. While the random selection could be adequately assessed by combinatorial methods, the ‘sinking effect’ allows neither intuitive consideration, nor any traditional mathematical means. The only practical way to treat this problem today is in simulation, but the simulation itself causes yet another problem: the problem of model adequacy. This study deals with one possible approach to the problem designated to prove its validity and adequacy, without which the simulation has naught gnoseological value.