THE GEOGRAPHY OF TRANSPORT SYSTEMS

International trade is based on the notion of exchange which involves what is being traded, the partners involved as well as the transactional environment in which trade takes place, namely custom procedures (tariff and non-tariff barriers). Commonly, international trade is seen as a series of commercial transactions between trade partners that tracks the value of what is being traded as well as the concerned nature of goods (such as standard international trade classification). Its extent, either in value or volume, is an abstract expression of the quantity of goods being exchanged as they do not represent the actual physical flows supporting trade.
The physical realization of international trade requires a transport chain which is a series of logistical activities that organize modes and terminals, such as railway, maritime and road transportation systems, and thus the continuity along the supply chain through a set of stages, the most common being:
In the operational reality of modes and terminals, international trade is a series of physical flows that may not necessarily use the most direct path, but the path of least resistance. The existence of inland corridors where economies of scale are more effective shapes the structure of freight flows and well as the selection of the port of exit. On the maritime side, transshipments hubs have become strategic intermediary locations helping consolidate maritime flows and connecting different maritime systems of circulation. In such a setting, the container has become the fundamental element facilitating transfers between modes and supporting international trade flows. Distribution centers play an important role in physical flows since they can act as a buffer helping reconcile the temporal and spatial requirements of demand.