Source: Rodrigue, J-P and T. Notteboom (2007) "Re-assessing Port-Hinterland Relationships in the Context of Global Supply Chains", in J. Wang et al. (eds) Inserting Port-Cities in Global Supply Chains, London: Ashgate.

A Multi-Layer Approach to Port Dynamics

Since ports are the nexus of maritime and inland transport systems, port hinterlands are strongly shaped by port dynamics, particularly over four inter-related layers ranging from a spatial to a functional perspective:

• The locational layer relates to the geographical location of a port vis-�-vis the central places in the economic space and forms a basic element for the intrinsic accessibility of a seaport. The concept of centrality and intermediacy fits well within this maritime locational perspective. A good intermediate location can imply a location near the main maritime routes such as offshore hubs (e.g. Singapore, Mediterranean load centre ports such as Marsaxlokk and Gioia Tauro) and/or near production and consumption centers such as gateway ports (e.g. Rotterdam, New York, Santos). For gateway ports, a good location is a necessary condition for attaining a high intrinsic accessibility to a vast hinterland, which often builds upon the centrality of the port region. It becomes a sufficient condition when the favorable geographical location is valorized by means of the provision of efficient infrastructures and transport services.
• The infrastructural layer involves the provision and exploitation of basic infrastructure for both links and nodes in the transport system. Containerization and intermodal transportation, particularly the transshipment infrastructures they rely on, have contributed to a significant accumulation of infrastructures in a number of ports. This is where the intrinsic accessibility is valorized since a port site has little meaning unless capital investment is provided.
• The transport layer involves the operation of transport services on links and corridors between the port and other nodes within the multimodal transport system and the transshipment operations in the nodes of the system. It is a matter of volume and capacity.
• The logistical layer involves the organization of transport chains and their integration in logistical chains. This layer is mostly managerial with a decision making process in terms of the allocation of modes and the booking of transshipment facilities.

In a demand-driven market environment the infrastructural layer serves the transport and logistical layers. The more fundamental the layer is, the lower the adaptability (expressed in time) in facing market changes. For instance, the planning and construction of major port and inland infrastructures (infrastructural level) typically takes many years. The duration of the planning and implementation of shuttle trains on specific railway corridors (transport level) usually varies between a few months up to one year. At the logistical level, freight forwarders and multimodal transport operators (MTOs) are able to respond almost instantly to variations in the market by modifying the commodity chain design, i.e. the routing of the goods through the transport system. As adaptable as they may be, they are still dependant on the existing capacity, but their decisions are often indications of the inefficiencies of the other layers and potential adjustments to be made.