Author: Dr. Jean-Paul Rodrigue

Transportation imposes an organization on activities and a spatial structure. Inversely, the spatial structure influences transportation.

1. The Spatial Organization of Transportation

The spatial organization relies on two dimensions that underline that uniformity rarely exists. The first relates to spatial differentiation, where attributes such as location, size, and density illustrate inequalities in the distribution of features such as population or resources. This differentiation results from a cumulative process of spatial accumulation as several elements of the spatial structure, such as urban areas, accumulate population and infrastructures at different rates and densities. The second relates to spatial interactions where flows illustrate inequalities in the characteristics of origins and destinations.

Transportation favors not only economic development but also has an impact on spatial organization. Throughout history, transport networks have structured space at different scales. The fragmentation of production and consumption, the locational specificities of resources, labor, and markets generate a wide array of people and freight flows. The structure of these flows in terms of origin, destination, and routing are closely related to spatial organization. Space shapes transport as much as transport shapes space, which is a salient example of the reciprocity of transportation and its geography. This reciprocity can be articulated over two points:

• Reciprocity to locations. This relationship concerns the transport system and the impacts it has on locations. Since the transport system is composed of nodes and links as well as the flows they support, the spatial organization of this system is a core defining component of the spatial structure. Transportation, by its physicality, shapes the spatial structure. Even if the streets are not the city, they shape its organization in terms of locations, orientations, and relations. The same applies to maritime shipping networks, which are not international trade but reflect the spatial organization of the global economy.
• Reciprocity to demand. This relationship concerns activities that are all dependent on transportation at different levels and different scales. Since every single activity is based on a level of transport demand and mobility, their relationship with transportation is reflected in their spatial organization. While a small retail activity is conditioned by local accessibility from which it draws its customers, a large manufacturing plant relies on accessibility to global freight distribution for its inputs (parts) as well as its outputs (finished goods).

The more interdependent an economy is, the more transportation becomes a support and a factor shaping its interdependencies. However, the importance of transportation can be neglected as interdependencies will be noticed while their structural support less so. The effect is being observed while its cause is not. Transportation infrastructures are constrained by a number of factors, including the physical environment, the level of demand, the available capital, and the regulatory environment. The relationship between transport and spatial organization can be considered from three major geographical scales; the global, the regional, and the local.

2. Global Spatial Organization

At the global level, transportation supports and shapes economic specialization and productivity through international trade. Improvements in transport are expanding markets and development opportunities, but not uniformly. The inequalities of the global economy are reflected in its spatial organization and the structure of international transport systems. Globalization incited a growth in spatial flows (trade) and increased interdependencies. Telecommunications, maritime transport, and air transport support most global flows because of their scale of service. The nature and spatial structure of these flows can be considered from two major perspectives that seek to explain global differences in growth and accessibility:

• Core / periphery. This basic representation assumes that the global spatial organization favors a few core areas that grow faster than the periphery, with differential growth creating inequalities in development levels. For instance, global migration flows are illustrative of different levels of economic development, with flows from locations with lower development levels to higher development levels dominating. Transportation is thus perceived as a factor of polarization and unequal development. From this perspective, parts of the global economy are gaining because they are more accessible, while others are marginalized and bound to dependency. However, this trend can be reversed if international transport costs are significantly reduced. This is evidenced by the substantial growth of many Pacific Asian economies that have opted for an export-oriented strategy that requires good access to global freight distribution. Consequently, the core/periphery relationship is flexible, relative, and can change over time.
• Poles. Transportation is perceived as a factor of articulation in the global economy, where the circulation of passengers and freight is regulated by poles corresponding to a high accumulation of transport infrastructures, distribution facilities, and economic activities. These poles are subject to centrifugal and centripetal forces that have favored the concentration of some activities and the dispersion of others. The global economy is thus based on the backbone of freight distribution, which relies on networks established to support its flows and on nodes that regulate flows within networks. Networks, particularly those concerning maritime shipping and air transportation, are flexible entities that change with the ebb and tides of commerce, while nodes are locations fixed within their regional geography.

Depending on their geographical and modal context, global flows are handled by poles labeled as gateways and hubs.

Gateway. A location offering accessibility to a large system of circulation of freight and passengers. Gateways reap the advantage of a favorable physical location such as highway junctions, the confluence of rivers, a good port site, and have been the object of a significant accumulation of transport infrastructures such as terminals and their links. A gateway is commonly an origin, a destination, and a point of transit. It generally commands the entrance to and the exit from its catchment area. In other words, it is a pivotal point for the entry and exit of a region, a country, or a continent and often requires intermodal transfers.

Hub. A central point for the collection, sorting, transshipment, and distribution of goods for an area. This concept comes from a term used in air transport for passengers as well as for freight and describes collection and distribution through a single point such as the “Hub and Spoke” concept.

The global spatial organization is a priori conditioned by its connectivity, often reflective of a network structure. Its main components are the nodes and the foreland (international connectivity, usually by maritime and air transportation) and hinterlands (regional connectivity, usually by land transport systems). Through the principle of economies of agglomeration and accessibility, a region can accumulate several major intermodal infrastructures, namely port, and airport terminals, reinforcing its connectivity. When these nodes act as an interface, they can be characterized as gateway systems (or regions) that play a substantial role in the global distribution of freight, connecting major circulation systems. Gateways also act as bottlenecks in global freight distribution, imposing constraints on their capacity, infrastructure performance, or supply chain management capabilities. Gateways emerged in the 19th century when rail transportation began structuring hinterland accessibility by allowing specific locations, such as ports, to command access to vast market areas. Later, the emergence of air transport enabled the setting of gateways between global and regional air transport systems.

Services are following a spatial trend that appears to be increasingly different than production. As production dispersed globally to lower-cost locations, high-level services focused on a relatively few large metropolitan areas labeled as world cities. They are centers for financial services (banking, insurance), head offices of major multinational corporations, innovation clusters, nexuses for the arts, and the seats of major governments. Gateways and world cities may not necessarily correspond as locations, underlining the ongoing dichotomy between central places (commercial imperatives) and transport places (distribution imperatives). This is particularly true for containerized traffic linked with new manufacturing clusters and intermediary hubs. The world’s largest container ports are not necessarily global cities, but many, such as New York, Shanghai, and Tokyo, are.

3. Regional Spatial Organization

Regions are commonly organized along with an interdependent set of cities, forming what is often referred to as an urban system. The key spatial foundation of an urban system is based on a series of market areas, which are a function of the level of activity of each center concerning the friction of distance. The spatial structure of most regions can be subdivided into three basic components:

• Locations of specialized industries, such as manufacturing and mining, tend to agglomerate according to location factors such as raw materials, labor, or market accessibility. They are often export-oriented industries from which a region derives the bulk of its basic growth.
• Service industry locations, including administration, finance, retail, wholesale, and similar services, tend to agglomerate in a system of central places (cities), providing optimal accessibility to labor or potential customers.
• Transport nodes and links, such as roads, railways, ports, and airports, service major centers of economic activity.

Jointly, these components define the spatial order of a region, mostly its organization in a hierarchy of relationships involving the mobility of passengers and freight. More or less well-defined urban systems spatially translate such developments, with the most important cities being the best connected and accessible while lower-order centers have less connectivity. This begets whether connectivity is an outcome of city size or if city size is the outcome of connectivity. Many conceptual models have been proposed to explain the relationships between transport, urban systems, and regional development, particularly core-periphery stages of development and network expansion theories. Three conceptual categories of regional spatial organization can be observed:

• Central places / urban systems models try to find the relationships between the size, the number, and the geographic distribution of cities in a region to explain variations in the regional spatial structure. Most urban systems have a well-established and stable hierarchy where a few centers dominate. Transportation is particularly important in such a representation as the organization of central places is based on minimizing the friction of distance. The territorial structure depicted by the central places theory is the outcome of a region seeking the provision of services in a (transport) cost-effective way.
• Growth poles where economic development is the structural change caused by the growth of new industries. The clustered location of these activities is the catalyst of the regional spatial organization. Growth poles first initiate, then diffuse, development. Growth is distributed within a regional urban system, but this process is uneven, with the core benefiting first and the periphery eventually becoming integrated with a system of flows. In the growth poles theory, transportation is a factor of accessibility, reinforcing the importance of poles.
• Transport corridors represent an accumulation of flows and infrastructures of various modes, with their development linked with economic, infrastructural, and technological processes. When these processes involve urban development, corridors are a system of cities oriented along an axis enabling commercial relations. Many urban regions, such as BostWash (Boston – Washington) or Tokaido (Tokyo – Osaka), share this spatial commonality. The development of high-speed train systems around the world takes place along major urban corridors and reinforces the existing regional spatial structure.

It is at the regional level that transportation has the most significant impact since the choice of routes reinforces the existing accessibility and may increase the importance of corridors. Therefore, transportation can be more of a factor in reinforcing regional inequalities.

4. Local Spatial Organization

Although transport is an important element in rural spatial organization, it is at the urban level that transportation has the most significant local spatial impact. Urbanization and transport are interrelated concepts, particularly with transport shaping the size and extent of cities. Every city relies on a need for mobility of passengers (residence, work, purchases, and leisure) and freight (consumption goods, food, energy, construction materials, and waste disposal). Urban demographic and spatial evolution transform the scale and scope of movements. Employment and attraction zones are the essential elements shaping the local urban spatial organization:

• Employment zones. The growing dissociation between the workplace and the residence is mainly due to the success of motorized transport, notably the private automobile. Employment zones located away from residential zones have contributed to an increase in the number and length of commuting trips. Before suburbanization, public transit was wholly responsible for commuting. Today, the automobile supports most of these trips, but the city supports a wide range of mobility options. This trend is particularly prevalent in highly populated, industrialized, and urbanized zones, but motorization is also dominant in developing economies.
• Attraction zones. Attraction zones linked to transport modes are areas to which a large number of individuals will travel for reasons such as shopping, professional services, education, and leisure. As with central places theory, there is a specific hierarchy of services within an urban area ranging from the central business district offering a wide variety of specialized services to small local centers providing basic services such as groceries and personal banking.

The development of cities is conditioned by transport, and several modes, from urban transit to the automobile, have contributed to creating urban landscapes. Three distinct phases can be noted:

• Conventional (classic) city. Constructed for pedestrian interactions and constrained by them, the historical city was compact and limited in size. The emergence of the first urban transit systems in the 19th century permitted the extension of the city into new neighborhoods. However, pedestrian movements still accounted for the vast majority of movements, and the local spatial organization remained compact. Many European and Asian cities still have a significant level of compactness, where urban transit remains a defining element of spatial organization.
• Suburbanization. The advent of more efficient urban transit systems and, later, the automobile permitted an increased separation between basic urban functions (residential, industrial, and commercial) and their spatial specialization. The rapid expansion of urban areas, especially in North America, created a new spatial organization, less cohesive than before but still relatively adjacent to the existing urban fabric. Although this process started in the early 20th century, it accelerated in the 1950s.
• Exurbanization. Additional improvements in mobility favored urban expansion in the countryside, where urban and rural activities are somewhat intermixed. Many cities became extended metropolitan regions with a wide array of specialized functions, including residential areas, commercial centers, industrial parks, logistics centers, recreational areas, and high-tech zones. These exurban developments have also been called “edge cities”.

The automobile has influenced contemporary urban spatial organization, but other socioeconomic factors have also shaped urban development, such as gentrification and differential changes in land values. The diffusion of the automobile has led to an urban expansion relying on the mobility of individuals and often conflicting urban functions (residential, industrial, commercial). Still, distance decay remains a force shaping urban spatial organization since suburban and exurban developments tend to occur as concentric rings within large metropolitan areas. Transport thus contributes to the local spatial organization. However, it must also adapt to urban morphologies. Transport networks and urban centers complement and condition each other.

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Related Topics

• 1.2 – Transportation and the Physical Environment
• 2.3 – Transport and Location
• 1.5 – Transportation and Commercial Geography
• 7.2 – Globalization and International Trade
• 8.1 – Transportation and the Urban Form
• B.3 – Gateways and Transport Corridors in North America
• B.5 – Transcontinental Bridges

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