ABSTRACT
More than 50 years ago Jacobs (1961) argued that a mix of functions and the various forms of cofunctioning between them was key to understanding how cities work. She noted that the modernist segregation of the city into monofunctional zones had the effect of preventing close connections of home to work, school, shopping, entertainment and recreation. An effective mix shortens the distances between wherever we are and wherever we need to be. For Jacobs the value of mix was in a general contribution to the social and economic vitality and intensity of the city. She distinguished between the primary functions that attract people to a given neighbourhood and the secondary uses that are sustained by those primary uses (Jacobs 1961: 160–161). Jacobs’ work has been increasingly embraced in urban planning, including the new urbanism movement (Grant 2005). More recently the question of functional mix has become an important focus in the fields of health and transport planning. Functional mix is a key ingredient of walkability, and higher levels of walking correlate in turn with lower levels of cardiovascular and other diseases (Frank et al. 2006). Transport flows are similarly enhanced by functional mix, and in this case the benefits accrue at every scale from the walkable neighbourhood to the metropolis (Cervero 1989). There are thus three main drivers of the demand for a better understanding of urban mix that will apply across different morphologies and scales: urban vitality/productivity, health and transport. However, the theory remains fragmented and undeveloped; basic questions about how to define the ingredients of the urban mix and the methods of measurement and mapping remain unresolved. It is the goal of this chapter to move this debate a step forward.
