Source: adapted from S. Hanson (1995), The Geography of Urban Transportation.
In motorized urban areas, mobility can be divided into five major spatial categories:
- Inside the central city. The central city includes the Central Business District (CBD) and the adjacent ring of high-density residential areas, including industrial and warehousing districts. These movements are usually serviced by high-density public transport systems such as subways, tramways, and buses. They used to be the dominant pattern of urban mobility, but this primacy has been rescinded with suburbanization.
- Towards the central area. Represents the classic pendular commuting pattern and is mostly linked to the tertiary and quaternary activities generally located in the central area. Cars are mostly a privileged mode, but public transit is used along major corridors, particularly if parking is limited. With the significant growth of economic activities outside central areas, this type of movement is less important than it used to be.
- Towards suburbia. Mostly linked with commuters living in central areas and having seen their jobs relocated to suburbia.
- Within suburbia (Lateral). With the demographic and economic development of suburbia, this type of movement is growing in importance. Since suburban areas are generally of lower density (with the exception of commercial clusters), transit systems cannot effectively service these areas. They are almost strictly the automobile domain and involve mobility from the suburbs towards small to medium-sized employment centers, particularly around highways.
- Exurbia. The emergence of economic activities in peri-urban areas (exurbia) has added a new dimension to urban mobility. These movements concern sparsely settled residential areas and employment centers loosely organized around clusters.
The above figure is illustrative of the United States, and the proportions are generic and will vary by metropolitan area.