Source: Adapted from Newman, P. and J. Kenworthy (1999) Sustainability and Cities: Overcoming Automobile Dependence, Washington, DC: Island Press, p. 180.
Each type of urban activity has its own mobility requirements that are serviced by the urban transport system and have locational preferences that vary according to urban transport infrastructures. Population-based activities (e.g. residential) are dominant where rail (e.g. subway and light rail) and bus infrastructures are converging, while freight based activities (e.g. manufacturing and warehousing) agglomerate nearby high capacity road infrastructures such as highways. Both activities and infrastructure are mutually self-reinforcing since they are part of a feedback loop.