The spatial organization of transportation and mobility
Environmental Externalities of Land Use
Economic Costs. The costs incurred to maintain the functionality of an urban area according to the characteristics of its land uses. Lower densities and specialized land uses increase economic costs in terms of average commuting distances, public utility provision, and energy consumption. Commonly, urban growth has occurred at the expense of the most productive rural land. Once land use shifts from rural to urban, it rarely becomes available for other uses, although there are cases where abandoned urban land reverted to vacant and even agricultural. High subsidy levels 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 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 dividing communities and disrupting non-motorized mobility (pedestrians, cyclists). Further, the design of a transportation system around a specific mode restrains accessibility to those who do not have access to that mode. This is notably the case for the automobile, which is a key determinant of the activity space of its users.
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.).