- Spatial form. Refers to the spatial arrangement of a city, particularly in terms of the orientation of its main axis of circulation. This form thus conveys a general structure to urban transportation ranging from centralized to distributed. The prevailing influence has been expansion and motorization, resulting in polycentric cities, which are economically and functionally flexible but consume more energy.
- Spatial pattern. Refers to the organization of the land use in terms of location of major socio-economic functions such as residence, commercial and industrial. The prevailing trend has been a growing disconnection and fragmentation between land uses. Also, different types of land use can be incompatible with their adjacency the source of additional externalities. For instance, residential land use is incompatible to the majority of industrial, manufacturing, warehousing and terminal activities activities as they generate noise and congestion externalities to which residents are highly susceptible. In such a context, buffers, which apply different barriers effects to promote physical separation, can be used to help mitigate incompatible land uses.
- Spatial interaction. Refers to the nature and the structure of movements generated by urban land uses. The prevailing trend has been a growth in urban interactions in terms of their volume, complexity and average distance.
|Economic Costs||Urban pattern and density||Average commuting distance|
|Density of population|
|Decrease in agricultural production|
|Energy||Gasoline use per capita|
|Energy per passenger km|
|Public utilities provision costs|
|Social Costs||Community disruption||Environmental externalities (e.g. noise)|
|Accessibility to facilities|
|Environmental Costs||Damage to the ecosystem||Land taken to the natural environment|
- Economic Costs. They are related to the costs incurred to maintain an urban area according to the characteristics of its land uses. Lower densities and segregated land uses increase economic costs in terms of average commuting distances, public utility provision, and energy consumption. In several instances, urban growth has always occurred at the expense of the most productive rural areas. Once land use shifts from rural to urban, it rarely becomes available for other usage. High levels of subsidies for urban transit are an indirect externality related to land use. It is increasingly difficult to provide adequate levels of service, notably in suburban areas, where land use density (residential and commercial) is not high enough for a profitable public transit system. Overall, land use externalities affect the economic efficiency of urban areas.
- Social Costs. Community disruption includes a wide range of social cost imposed by the land use density, pattern and interaction. Environmental externalities, like noise, smog and odors, contribute to disrupt the quality of life. Transportation infrastructure, notably railways and highways are a physical barrier that divides a community and disrupt pedestrian / vehicular linkages. Further, the design of the transportation system for a specific mode restrains accessibility of persons who do not have access to that mode. This is notably true with cars.
- Environmental Costs. The most obvious environmental cost is related to the quantity of land taken at the expense of the natural environment. It must also be considered that land use contributes to environmental degradation as a source of waste, particularly for industrial activities (air pollution, water pollution, hazardous materials, etc.).
- Densification. Involves a more rational and intensive use of the existing land uses to minimize the environmental footprint and the level of energy consumption. Yet this implies higher levels of capital investment and the provision of an adequate level of public transit, since in a car-dependent context densification easily leads to congestion and other externalities.
- Devolution. Due to economic and demographic trends several cities could lose a share of their population, imposing a rationalization of urban land uses. In old industrial regions of Europe and North America, several cities have lost a share of their economic base and correspondingly their population. This involves dismantling urban infrastructure and closing sections or whole neighborhoods, which could lead in time to the emergence of urban forests and even forms of urban agriculture. Detroit is a salient example since the population of the city dropped by more than a half from 1.8 million in 1950 to 713,000 in 2010. Yet, the population of its metropolitan area has remained relatively stable since the 1970s, hovering around 4.2 million. This implies that the process of devolution is very location specific.