THE GEOGRAPHY OF TRANSPORT SYSTEMS

Source: adapted from T. Toikka (2006) "The Real Price for Container
Transportation between Asia and Europe", Lappeenranta University of
Technology, Department of Industrial Engineering and Management.
Depending of the characteristics of the goods being carried, namely the weight-to-volume ratio, a 20 footer may not be the optimal containerized unit. For instance twice as much cell phones, DVD players or shoes could be carried on a 40 footer without infringing the weight restrictions, which are at about 27,000 kilograms. The cargo runs out of available volume before running out of available weight ("weighting out" versus "cubing out"). Since the costs of handling a 40 footer are not much higher than a 20 footer, there are notable advantages at using this load unit (or better a high cube 40 footer) instead.
For ponderous goods such as copying paper, the 20 footer is the optimum load unit as about 1,700 units each weighting just over 20,000 kilograms can be carried, which is the maximum. Using a 40 footer for such a load, which is twice the volume, would carry only 2,150 units (27.6% more). Yet, a 20 footer may be a suitable unit for goods with a a low weight-to-volume ratio if the demand of the consignee is not high enough to justify a more efficient load (40 foot) or if freight distribution is more dependent on higher frequency and smaller batches.