Source: adapted from Taaffe, E.J., H.L. Gauthier and M.E. O'Kelly (1996) Geography of Transportation, Second Edition, Upper Saddle River, NJ: Prentice Hall.
Corridor Development
The development of transportation networks commonly leads to the creation of corridors. A model has been developed by Taaffe, Morrill and Gould (1963) to explain this process. Although this model specifically applies to empirical evidence derived from transport development in West Africa, it can be applied elsewhere, such as in North America. Six phases summarize the model:
- Phase A (Scattered ports). A set of small trade ports are established along a coastline. They are connected to a wider network of trade and provide access to locally supplied resources.
- Phase B (Penetration lines and port concentration). Trade lines accessing the hinterland are constructed permitting the development of new resources and/or markets. The ports to which they are connected grow in proportion to the new traffic generated.
- Phase C (Development of feeders). The hinterland of penetrating lines is further expanded by the development of feeders.
- Phase D (Beginning of interconnections). The transport networks that have so far been developing independently gradually become interconnected. Intermediate centers also start to emerge.
- Phase E (Complete interconnection). As the level of connectivity increases, traffic tends to concentrate in the most connected ports (often corresponding to the largest cities), implying that several less well connected ports decline or disappear.
- Phase F (Emergence of high priority links). Economies of scale favor the concentration of the traffic along the most efficient links, supporting the emergence of transport corridors. Links having lower volumes can even be closed down. The regional transport system has thus reached a phase of maturity and the structure of the network is unlikely to change unless of significant economic or technological developments.