Source: Rodrigue, J-P, C. Comtois and B. Slack (1997) "Transportation and Spatial Cycles: Evidence from Maritime Systems", Journal of Transport Geography, Vol. 5, No. 2, pp. 87-98.
Cycles, Space and Transportation
Since transportation technology is widely standardized, cycles represent different scales of spatial change of a transport system. However, some transportation systems have limited potential for spatial diffusion, simply because of the scale of their geographical system, such as public transit that covers at most a metropolitan area. Transport development and spatial diffusion are closely linked. The growth and contraction of the transport system is commonly taking place through a hierarchical diffusion process influenced by the existing network structure of the network. As highly dynamic entities, networks are the agents, and, at the same time, recipients of the spatial diffusion of transport systems.
The above figure provides a synthetic representation of a cycle impacting two transport systems, one which is local in character and the other that encompasses the world. Cycle C1 represents the diffusion of a transit system closely related with urban growth and decline, but also with competition from other modes. From A to B, cycle C1 experiences periods of introduction, growth and maturity, while after B, obsolescence and/or competition are causing a decline in ridership. This has been the fate of public transit in a number of North American cities since the 1960s. Cycle C2 is more indicative of a transport system servicing international trade, like containers shipping. With an initial state effecting a service area of limited geographical coverage (a few ports for instance; C), growth and maturity provide a transportation system covering a global scale and often takes the shape of a hub-like to minimize operation costs while maintaining good market (spatial) coverage (D). It is not imperative that transport systems after reaching their peaks, irremediably enter a phase of decline and eventually obsolescence. This will only take place of they cease to have a commercial utility.