The Core Principles of Transport Geography
Transport geography can be better understood from a series of core principles:
  • Transportation is the spatial linking of a derived demand. It takes place because of other economic activities and is linking the spatial components of this demand. For instance, commuting is the spatial linking of labor flows resulting from the demand for labor at one location (e.g. a commercial district) and its supply at another (e.g. a residential district). A market economy could not function without the capacity of transportation to link supply and demand.
  • Distance is a relative concept involving space, time and effort. How distance is perceived is a function of the amount of effort made to overcome it. These efforts can be assessed in terms of spatial distance, time distance or other effort measures such as cost or energy spent to overcome distance.
  • Space is at the same time a the generator, support and a constraint for mobility. It is the formal context in which mobility takes place, so space can be a support for mobility as it will shape the nature and structure of the transport system. At start, spatial differences in attributes such as resources, employment and demand act as generators and attractors of movements. How space acts as a constraint for transport is often relative and paradoxical. For instance, a river acts as a constraint for land transport systems such as roads and railways, but represents the support for fluvial transportation (if the river is navigable). At the same time that the atmosphere is the physical support for air transport operations, the weather can be a constraining factor under specific circumstances (e.g. snowstorms, thunderstorms, hurricanes). Further, transportation is a space by itself, an activity space, implying that during the transportation process, either in modes or at terminals, socioeconomic activities are taking place.
  • The relation between space and time can converge or diverge. Every form of transport involves the consumption of a unit of time in exchange of a given amount of space. Over time this process has mostly converged, implying that a greater amount of space can be reached with the same amount of time (or the same amount of space can be reached with a lesser amount of time). This is jointly the outcome of technological improvements as well as a better capacity and extent of transport infrastructures. The relation between space and time can also diverge when congestion starts to be significant and that each additional unit of movement results in additional delays.
  • A location can be a central or an intermediate element of mobility. Locations are said to be central when they act as generators (origins) or attractors (destinations) of movements. Locations are labeled as intermediate when movements are passing (transiting) through them on their way to other locations. Ports and airports are often intermediate locations since they act as gateways or hubs within a complex transport network.
  • To overcome geography, transportation must consume space. Transportation infrastructures are important consumers of space, which includes the pathways (e.g. roads and rail lines) as well as the terminals. The more extensive a transport system and the higher the level of mobility, the more extensive its consumption of space. For instance, in highly motorized cities, roads and parking space can consume up to 50% of the land. Globalization has been linked with the setting of massive terminal facilities such as container ports and airports. While space consumed by road infrastructure is mostly linked with local and regional activities, the space consumed by rail, port and airport terminals is linked with activities taking place at a higher scale.
  • Transportation seeks massification but is constrained by atomization. Transport systems are the most effective when they develop economies of scale, particularly in terms of the loads (passengers or freight) they can carry. Massification involves conveyances with higher capacity and supported by larger terminals. However, more than often the first and last segments of a transport sequence require atomization, which implies that transport loads (passengers or freight) must be consolidated and deconsolidated. So, the higher the level of massification, the more complex atomization becomes.
  • Velocity is a modal, intermodal and managerial effort. Velocity does not necessarily mean speed, but the time it takes for a passenger or a unit of freight to move across a complete transport sequence. For instance, the speed advantage of air transportation is undermined if a passenger is spending several hours between connecting flights. Therefore, the velocity of passengers or freight is a joint consideration of the effectiveness of the respective modes involved, as well as that of the intermodal operations connecting the modes. In addition, the complexity of transport systems requires an effective management of its operations, such as scheduling. All of the above jointly contribute at improving the velocity of flows carried by transport systems.