Cities, networks, polycentrism: examining the place of polycentrism in spaces of flows

In a globalising world economy, cities have increasingly come to be defined not by the size of their built up area or population but by their functions in networks that connect them to capital flows that cross territorial boundaries (Rozenblat 2010). As Sassen (1991, p. 631) wrote it in her global cities book, ‘massive trends toward spatial dispersion of economic activities at the metropolitan, national and global level, which we associate with globalisation, have contributed to a demand for new forms of territorial centralisation of top-level management and control operations’. As centralities for management and control functions in network enterprises operating at different spatial scales, globalising cities can be expected to be economically vibrant owing to their role in facilitating the circulation and accumulation of intellectual and financial capital. Moreover, according to protagonists of Jacobs (1984), the vibrancy of these cities spills over metropolitan boundaries to form prosperous globalising city regions (Scott 2001a, 2001b; Hall and Pain 2006). A new paradigm of city networks, functions and flows has therefore overtaken the traditional paradigm of places and territorial borders as the structure of the contemporary global space economy. In the networked economy that has been evolving for half a century, it follows that city regions are differentiated not only by their physical pattern of urban development, but also by their functional pattern in network space. In consequence, city-region spatial form (morphology) and city-region Jacobsean economic expansion, while interrelated, are distinctive development processes that should not be confused with each other (Taylor and Pain 2007; Pain 2012). However, the concept of polycentrism has referred to morphological space without paying due regard to network space, functions and flows, for almost two decades in a policy to rebalance uneven regional economic development in Europe (European Commission 1999; Davoudi 2003; Duhr and Nadin 2005; Halbert et al. 2006; Pain 2008). Thus, European spatial planning strategy has promoted the development of polycentric urban regions (PURs) based on examples of regions populated by many similar-sized urban centres, such as the Randstad region in the Netherlands and the Rhine-Ruhr region in Germany, which are regarded as a superior spatial form to monocentric regions dominated by one centre such as South East England and the French Paris region.