Polycentrism and ?defragmentation?: towards a more sustainable urban form?

JENKS, MIKE; KOZAK, DANIEL

World Cities and Urban Form: fragmented, polycentric, sustainable?

Routledge

Lugar: Londres, Nueva York; Año: 2008; p. 71 - 94

With the rapid increase in urbanisation worldwide, particularly in Asia, and the growth in the number of very large cities and metropolitan regions, the need to achieve more sustainable urban forms is becoming critical. The sheer scale of the changes from a rural to a predominantly urban world population leads to some questions about the adequacy of our existing knowledge and the paradigms of urban sustainability. Evidence is beginning to emerge that some policies and forms that could be suggested as appropriate for world cities and their regions, and for cities experiencing rapid growth through in-migration of rural populations. At the regional level, networks of cities and polycentrism have claims to interconnections that, although characteristic of globalization, may have some potential for sustainability. At the city level polycentric development may have, or at least is claimed to have, the potential to achieve more sustainable forms, provided all the 'nodes' are linked with efficient public transport. At this level, and within urban areas, promising urban forms may include 'transit oriented development'. Linking public transport and development may take a number of different forms, including the intensification (or densification) of development around transport interchanges ? transit development zones (TDZ) (e.g. see TOD/TDZ website, 2004). TDZs may include higher density residential development with commercial facilities and other services. Major transport routes may also provide the opportunity for denser development along the routes, and this has been successfully undertaken in Curitiba in Brazil and in Bogota, Colombia, with its 'Transmilenio' bus rapid transit system. So is polycentrism a form that can help world cities become more sustainable, or is it another hopeful planning ideal that has credence in theory but problems in practice? This chapter considers the concepts associated with polycentrism and some of the implications of this emerging urban form. Aspects of two world cities, Buenos Aires and Bangkok, are then examined in more detail to uncover the nature of their polycentric forms and whether these represent the fragmentation of the cities, or contribute towards sustainability. Finally some ideas are proposed about 'defragmenting' the city to achieve more sustainable urban forms in world, mega- or very large-cities.