Whereas European spatial planning in the 1980s was mainly concerned with land-use regulation and specific development projects, the 1990s were characterised by a revival of strategic spatial planning (Albrechts et al., 2003; Albrechts, 2004; Healey, 2004). This reorientation in spatial planning meant a shift in focus from the physical planning of space-using functions such as hospace-using, industry, transport and nature to the development of strategic frameworks and new visions for regional development. This resurgence of interest in strategic spatial planning can be seen as a departure from the neoconservative and postmodern disbelief in the ‘makeability of society’ (Albrechts, 2004) and is fuelled in part by the problems of coordinating public policy, promoting urban and regional competitiveness through the development of a collective asset base and mitigating inequalities of opportunity across cities and regions (Healey, 2004).
In this ‘new’ strategic spatial planning (cf. Healey, 2004), polycentricity is a catchphrase; polycentric development policies have mainly been introduced to encourage a more balanced spatial distribution of economic activities between geographic units (cities, regions) across an area as well as higher levels of urban and regional competitiveness (Meijers and Romein, 2003). The rationale behind such policies differs from area to area and ranges from the overconcentration of economic activities in one place and the underutilisation of resources in other places to the desire to prevent exodus from rural areas, promote environmentally sustainable development, and increase economic and social cohesion and solidarity in general (Meijers et al., 2007).
Polycentricity can mean different things at different geographical scales (Kloosterman and Musterd, 2001; Davoudi, 2003; Meijers et al., 2007; Vandermotten et al., 2008). At the level of the European Union, polycentricity has mainly been introduced to stimulate growth outside of the areas known as the ‘Pentagon’ “to ensure regionally balanced development, and create global economy integration zones” (Commission of European Community, 1999, para. 67). At the national level, polycentric development policies have aimed to achieve competitiveness and cohesion by reducing disparities in development between regions and between cities at different levels in the national urban hierarchy (Meijers et al., 2007). At the regional level, academic discussion and policy debate has predominantly focused on the development of Polycentric Urban Regions (PURs), which can be best described as a set of historically and spatially separate metropolitan areas comprising a larger, functionally interrelated urban region (Kloosterman and Musterd,
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2001). As indicated by Faludi (2004), such polycentric spatial constellations are supposed to be more competitive than their monocentric counterparts because they provide opportunities to take advantage of some of the positive factors associated with large agglomerations, such as broader labour markets, luxury goods and services and airports, while avoiding some of the negative factors associated with such agglomerations, such as pollution, crime and congestion.
Despite the scale-dependent interpretation of polycentricity, one of the common characteristics of polycentric development policies is that they all seek the spatial integration of particular regions (i.e., the enlargement of particular functional regions) through urban network development. At the continental and national levels, it is believed that equality will be improved by strengthening urban-rural relationships through the creation of a network of internationally accessible metropolitan regions (well-distributed across the European Union or across the country in question). At the regional level, functional linkages between medium-sized cities and towns within a PUR are promoted to achieve synergies between the different parts of the region (Meijers, 2005) and so that they will be able to compete with their monocentric counterparts, such as London and Paris (Dieleman and Faludi, 1998). This is supposed to create a favourable setting for economic growth, especially when the cities and towns in such an urban network complement each other in terms of their economic specialisations. Polycentric development policies seem to combine the ostensibly conflicting objectives of regional cohesion and competitiveness (Waterhout, 2002).2
Although polycentricity has featured prominently as a normative strategic planning concept in policy documents and the academic literature, less attention has been paid to polycentricity as an analytical construct for studying the spatial organisation of geographic areas (Van Houtum and Lagendijk, 2001; Davoudi, 2003). Indeed, most of the planning and geography literature has focused on polycentricity as a spatial-planning vision as well as on capacity-building in and governance of polycentric areas, where polycentricity is perceived as a goal in itself. However, the number of studies that assess empirically how well the polycentric model fits the reality of contemporary urban systems is gradually increasing. This development has been spurred not only by an increase in the availability of data on urban networks but also by the increasing need to assess the validity and usefulness
2 At the same time, evidence that a polycentric region was functionally integrated would also support planning on larger geographical scales than that of the city or region in question to manage those spatial interdependencies (Turok and Bailey, 2004).
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of the notion of polycentricity in the context of polycentric development policies (Meijers, 2008b).
In particular, many scholars have questioned the extent to which PURs really operate as functionally integrated entities and whether spatial planning really contributes significantly to the development of a PUR (see, for example, Albrechts, 2001). Although it is often argued that the monocentric city is being replaced by the polycentric urban network as the dominant form of spatial organisation, it remains unclear to what extent the PUR model accurately reflects spatial reality. The existence of multiple urban centres in close proximity to each other does not necessarily even imply that there are strong functional links between those centres, let alone that the ostensible PUR is functionally polycentric in that the orientation of the functional links (for example, commuting, shopping, and trade) within that PUR are multidirectional. Taking these considerations into account, several scholars have argued that there is limited spatial integration and urban network formation at the level of the PUR, even in regions that are considered archetypical PURs from a morphological point of view, such as the Basque country (Van Houtum and Lagendijk, 2001; Meijers et al., 2008), the Randstad in Holland (Lambooy, 1998;
Lambregts et al., 2006; Van Oort et al., 2010), and the Flemish Diamond (Albrechts, 2001;
Cabus and Vanhaverbeke, 2006; Hanssens et al., 2011). As a PUR cannot exist in practical terms without a minimum amount of interaction between the various parts (Champion, 2001; Parr, 2004; Governa and Salone, 2005), this purported lack of integration raises serious questions for the many policy attempts to initiate and sustain polycentric economic-development trajectories in Europe.
However, Lambregts (2009) rightly notes that the degree of polycentricity and spatial integration that can be seen in a particular region is highly dependent on the indicators used to measure it. Urban networks are multiplex phenomena and, therefore, polycentricity and spatial integration can be studied by evaluating different types of functional linkages between cities and regions, for example, commuter trips (Van der Laan, 1998; Aguilera, 2005; De Goei et al., 2010; Burger et al., 2011a), telephone calls (Camagni and Salone, 1993; Halbert, 2008), intra-firm networks (e.g., the POLYNET study documented in Hall and Pain (2006) and Hoyler et al. (2008)), and inter-firm networks (Van Oort et al., 2010;
Hanssens et al., 2011). The spatial organisation of each of these types of functional linkages is not necessarily similar and, therefore, a region may appear polycentric and spatially integrated with respect to one type of functional linkage but monocentric and
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loosely connected with respect to another type of functional linkage.3 Most of the empirical studies have evaluated the spatial organisation of regions by looking only at one, or at most two or three, types of functional linkages. Similarly, spatial planners have limited themselves to mere abstract descriptions of concepts such as the PUR and have difficulty envisioning regions in a more refined way, partly due to a dearth of data on how a given city or town is linked with other places in the wider territory (Healey, 2004; 2006). As the appropriate level for meaningful policy-making differs across types of functional relationship, it is difficult to develop a cohesive set of policy recommendations for PUR development based on only one type of relationship.
The aim of this chapter is to stimulate further discussion on the multiplexity of urban networks in the context of polycentric development policies and the ‘relational complexity’
(cf. Healey, 2006) of urban regions. Focusing on the PUR and comparing the geographic scope and spatial structure of different functional networks, we analyse the extent to which different urban networks overlap. In this study, we examine the networks of the Randstad region in the Netherlands, which has been described as an archetypical PUR in the geography and planning literature (Lambregts et al., 2005; 2006). We argue that by taking into account the multiplexity of urban networks, to the meaning of functional polycentricity, spatial integration and urban network development at the level of the PUR from an analytical point of view can be better understood. With respect to polycentricity as a normative planning strategy, insights into the complex structure of polycentric areas will help policy-makers to decide what functions would be best organised at the PUR level. At a more general level, this investigation makes a valuable contribution to the debate regarding the appropriate scales for governance.
The remainder of this chapter is organised as follows. Section 4.2 gives a more detailed introduction to the notions of functional polycentricity, spatial integration, and the multiplexity of urban networks. Section 4.3 introduces the Randstad region in the Netherlands as an empirical setting and describes the data and the methodology. Section 4.4 summarises the empirical results, and Section 4.5 presents a discussion of the implications and our conclusions.
3 This has been demonstrated empirically by, for example, Lambregts et al. (2005; 2006), whose analyses of commuting patterns, intra-company office networks and inter-company business-services networks give very different pictures of the spatial organisation of the Randstad region in Holland. Similar conclusions can be drawn with regard to other regions based on the work of Limtanakool et al. (2009) and Lüthi et al. (2010).
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