Polycentricity, Performance and Planning: Concepts, Evidence and Policy in Barcelona, Catalonia

摘要

Problem statement More than half of the world’s population currently lives in urban settlements, a proportion that is expected to increase to more than 65 percent by 2050 (UN, 2014). The larger agglomerations are a complex spatial configuration of places and flows that are polycentric by nature, or at least they demonstrate a certain development of a multi-center structure. Recently, the focus on agglomerations’ polycentric structure has attracted a great deal of attention from both researchers and policymakers, who must manage the economic, social, and environmental challenges that the population of these metropolitan agglomerations will experience in the coming decades. In research, a considerable portion of the study of polycentric agglomerations has focused on the conceptualization of polycentricity and the empirical analysis of its economic, social, and environmental dis(advantages). Although academics have made a strong effort both to clarify the concept of polycentricity and to empirically explore its dis(advantages)—see, e.g., the special issues of journals such as European Planning Studies (1998; 2015), Urban Studies (2001) and Regional Studies (2014)—two major issues remain in the literature. First, various approaches to polycentricity co-exist without a high level of integration. One approach refers to polycentricity on the intra-urban (Davoudi, 2003) or intra-metropolitan scale (Brezzi and Veneri, 2015; Limtanakool, 2006), whereas another refers to polycentricity on the inter-urban (Davoudi, 2003) or regional scale (Brezzi and Veneri, 2015; Veneri and Burgalassi, 2012). Moreover, when these approaches are integrated, they are often conflated, at least to an extent (Van Meeteren et al., 2015). Second, empirical examinations of the economic, social and environmental advantages of polycentricity have not yet led to conclusive findings (see, e.g., Burger, 2011; Lee, 2006a; Meijers, 2007a). In the policy realm, polycentric development appears to be the main hallmark of spatial plans for metropolitan areas worldwide. Indeed, more than 75 percent of recent spatial plans developed for large metropolitan areas in OECD countries consider polycentric development as the best strategy for managing urban development. Some of the key policy objectives that polycentric development is expected to fulfill include offering an economical, efficient transportation system and a sustainable environment, along with extending access to education, jobs, amenities, and decent housing to a large number of people. Policy experts’ current interest in polycentricity is rooted in the early 1990s, when after two decades of focusing on local urban development projects and land-use regulations, planning practice refocused its attention on producing strategic frameworks and visions for territorial development in cities and metropolitan regions, strongly emphasizing their relationship with sustainable development (Albrechts et al., 2003). Polycentric development therefore re-entered planning practice as a bridging concept between sustainable development (broadly interpreted as fulfilling economic, social, and environmental objectives) and territorial development. However, the understanding of polycentric development in current planning policies appears largely disconnected from the ongoing polycentricity debate in research. This lack of connection between the understanding of polycentricity in research (evidence) and in policy (spatial plans) becomes apparent when considering the issue of how polycentric development can be conceptualized in spatial plans and how the assumed benefits of polycentricity can be realized in planning practice. This issue is of great importance to facilitating a more evidence-informed planning in which polycentricity appears as a bridge-building tool between research (evidence) and policy (spatial plans) with the aim of improving the feasibility and effectiveness of spatial plans’ economic, social, and environmental objectives. It is necessary to conduct a further exploration of the three aforementioned major issues related to (1) the conceptualization of polycentricity, (2) the empirical analysis of the dis(advantages) of polycentricity, and (3) how to interpret the relationship between polycentricity in research and polycentricity in policy. That is the key motivation for this thesis: to link the knowledge of polycentric constellations and their economic, social, and environmental effects to planning practice and policy in metropolitan areas. General aims and questions The overarching research goal of this dissertation is to contribute to the debate on polycentricity in the three interrelated issues mentioned above. First, it aims to renew the conceptualization of polycentricity by bringing together two distinct literatures, namely, the literature on intra-urban polycentricity and the literature on inter-urban polycentricity. Second, it aims to empirically substantiate the relationship between polycent