Source: adapted from Camagni, R., M.C. Gibelli and P. Rigamonti (2002) “Urban Mobility and Urban Form: the Social and Environmental Costs of Different Patterns of Urban Expansion”, Ecological Economics, Vol. 40, pp. 199–216.
The urban expansion of land uses can take place in five general forms:
- Infilling. New developments are set in previously unused or redeveloped areas for new uses. Brownfield redevelopments are a good example of urban expansion opportunities on sites that have lost their economic significance, such as old industrial sites, abandoned terminals (waterfronts or rail yards), and shopping malls.
- Extension. A standard form of expansion where land use is a development directly adjacent to existing land uses. New infrastructures such as streets and utilities are expanded from the existing network.
- Linear development. Similar to extension, but in this case, the expansion is shaped by an existing circulation corridor such as a highway or a transit line (subway, light rail). It directly takes advantage of the accessibility offered by the transport infrastructure.
- Sprawl. A standard form of suburban development taking advantage of scattered lots. Each developer is taking advantage of an existing plot of land without considering the existing urban pattern.
- Large-scale projects. The setting of a large infrastructure project such as a new port, airport, industrial zone, logistics zone, or intermodal rail terminal consumes a large amount of land. Its operational rationale is often very different from the existing landscape, so the level of integration to existing land uses can be limited. These projects often act as the impetus for new surrounding developments.