Polycentric Urban Research Articles

Polycentric Urban System, Territorial Development and Resilience of the Rural Population (Extremadura, Spain)

Over the last several decades, cities have seen concentrated development and population increase. It is a global process, still unfinished, that has simultaneously generated strong territorial imbalances because of socioeconomic backwardness and depopulation of rural areas. The alternative proposed by all institutions is a polycentric urban system, so that cities contribute to decentralizing this development towards their respective areas of influence, thus stabilizing the populations in them. Extremadura is a paradigmatic example, since it has a polycentric system of small cities that have been able to retain half of the population in rural areas. The objective of this article, first, is to define the urban structure and, based on this, typify the range, the hierarchy of the system and its territorial distribution, for which a multivariate analysis is applied. Secondly, a series of isochrones and displacement ranges are defined to analyze urban accessibility, which is key to determining the degree of decentralization of development and population stability. However, a wide peripheral and remote strip remains in the region, for which a concrete proposal is finally made for discussion.

Morphological and Functional Polycentric Urbanization in Colombo Metropolitan of Sri Lanka Using Time-Series Satellite Images from 1988–2022

Examining urban growth in metropolitan areas from both morphological and functional perspectives is paramount for sustainable development in developing and developed countries. As a collaborative and critical approach, polycentrism operates concurrently at local, regional, and national levels. However, the decentralized morphologies and functional attributes of polycentric urban spaces are yet to be adequately explored, despite their significant influence on sustainable urban planning and management. Colombo, the only metropolitan area in Sri Lanka, has experienced considerable yet ambiguously imbalanced spatial growth due to insufficient data. This study employed time-series satellite imagery from 1988 to 2022, in conjunction with a network model, to elucidate Colombo’s uneven urban patterns, while achieving an accuracy of over 80% throughout the period. The results revealed that the metropolis has evolved into a polynuclear city, complicating the identification of centers and their corresponding developmental stages. Nevertheless, the study successfully pinpointed the morphological and functional Grama Niladhari divisions, disclosing the morphological features of centralized dispersion and the functional traits of decentralized concentration. These insights provide significant implications for local government, guiding urban planning initiatives to achieve sustainable development goals.

Polycentric Urban Spatial Structure Identification Based on Morphological and Functional Dimensions: Evidence from Three Chinese Cities

Regarding whether a polycentric urban spatial structure is a sustainable urban development model, various studies use different employment center identification methods, resulting in inconsistent conclusions. This paper takes Hangzhou, Wuhan, and Nanning, three Chinese cities at different stages of development as cases, and adopts various methods to identify employment centers to compares the polycentric spatial structure differences from morphological and functional dimensions, and puts forward a multi-dimensional perspective for analyzing the characteristics of the polycentric spatial structure. The results show that the polycentric model of GL_SC threshold method has the relatively good explanatory power, which can best represent the characteristics of urban development in China. The explanatory power of the polycentric model of the Wuhan commuter flow method (adjusted R-squared value is 0.37) is slightly weaker than that of the GL_SC threshold method (adjusted R-squared value is 0.40), indicating that the agglomeration development forces are equivalent to the decentralized development forces and it is a balanced polycentric development structure. In Hangzhou and Nanning, the GL_SC threshold method (adjusted R-squared values are 0.28 and 0.36, respectively) is stronger than the commuter flow method (adjusted R-squared values are 0.19 and 0.33, respectively), which reflects the strong characteristics of agglomeration polycentric development. However, from the comparison of the number and distribution of employment center identification, the polycentric development characteristics of Hangzhou are stronger than those of Nanning. The comparison of the identification results of the morphological and functional dimensions shows that the two dimensions as a unified evaluation process can more fully reflect the characteristics of an urban polycentric development structure, thereby providing preliminary research support for the study of the impact of polycentric structure on economic development, air pollution, work and residential commuting, etc.

Global Connectivity, Spatial Proximity, Multimodal Transport, and Polycentric Urban Regions: UAE Urban Development 2020 - 2030

At a current world city scale, conurbations interweave complex multimodal systems of logistics, transport, and communications. As this process evolves into a global network of interconnected urban nodes. While diffusing globally, China’s One Belt One Road (OBOR) proposal creates an infrastructural framework for global exchange, analogous to the Ancient TransAsian links of Silk Road and Indian Ocean. Linked spatial dimensions and functional regions have always existed at different scales without any synchronized nomenclature for a grid with exact dimensional measurements. The global surface exists as a topological phenomenon of multi scalar dimensions covered by varied surface phenomena from earth to vegetation with fluid elements alternating in liquidity and flows. increasingly the world cities trend divides more advanced urban regions from less well viably connected territories, governments, industries, and commerce. Thus, the world has been experiencing an unequal distribution of trade and associated transport, logistics and handling facilities. In relation to global trade and transport tends to focus on the post-industrialized West and East and so underplays the role of other parts of the world system, including the MENASA (Middle East–North Africa–South Asia) region. In doing so, scholars discount a variety of spatial, morphological, environmental, historical, and socio-political urban patterns particular to these other regions and cities. This article addresses this oversight by examining the United Arab Emirates coastal conurbation (U.A.E.–CC, including Dubai–Abu Dhabi–Sharjah–Ajman), with its unique global positioning and political and economic conditions. The U.A.E.–CC is explored in relation to theories of the world/global city, the airport city or aerotropolis, and the polycentric urban region (PUR). The article demonstrates the emerging formation and potential of the U.A.E.–CC PUR, a member of a world-city network specializing as a transport hub and tourist destination and a global logistics center.

To What Extent Can Satellite Cities and New Towns Serve as a Steering Instrument for Polycentric Urban Expansion during Massive Population Growth?—A Comparative Analysis of Tokyo and Shanghai

In response to the call of the New Urban Agenda—Habitat III for a reinvigoration of long-term and integrated planning towards sustainable urban development, this paper presents an empirical comparative study of planning practices based on the “satellite city” and “new town” concepts in Tokyo and Shanghai to examine from a long-term perspective how well they have guided polycentric urban development at a time of massive population growth. We aim to deliver evidence-based contributions to boost the knowledge transfer between the Global North and the Global South. The paper adopts a multi-dimensional framework for the comparative analysis, including a review of long-term urban development policies and an inspection of the population distribution and extent of built-up areas using time-specific categorizations to map the spatiotemporal changes based on GHSL data. The comparative analysis shows that urban plans in Tokyo and Shanghai based on satellite cities and new towns as steering instruments for polycentric urban growth management have not lived up to the original aspirations. In fact, the intended steering of population distribution has essentially failed, despite the practical steps undertaken.

Using Remote Sensing Data and Graph Theory to Identify Polycentric Urban Structure

Polycentric urban structures determine the combination and correlation of urban resources. In the past, nighttime light data were often used to identify the center locations, but the borders of polycentric urban regions (PURs) could not be obtained. Using multisource remote sensing data and graph, this research proposes an effective method for polycentric structure identification. First, we regard nighttime light data as a continuous mathematical surface, which can be constructed as nighttime light intensity graphs (NLIGs). Then, the space-optimized Girvan–Newman (SGN) method is proposed to detect the communities, and the eigenvector centrality (EC) and gray value are used to discover the central node of each community. Finally, the geographical location mapping (GLM) between Landsat 8 data segmentation objects and nodes is established, and the PURs and centers can be mapped to the communities and central nodes. This study took Shenyang, Chengdu, and Xi’an as study areas and used monthly Visible Infrared Imaging Radiometer-National Polar-orbiting Partnership (NPP-VIIRS) data in April 2019 and Landsat 8 data in January and August 2019. The average accuracies of PURs and centers identified by the proposed method were 86.24% and 72.5%, respectively. The developed method can provide technical support and data support for urban planning.

Impact of Polycentric Urban Network on Industrial Structure Upgrades: Evidence from the Yangtze River Economic Belt

Impact of Polycentric Urban Network on Industrial Structure Upgrades: Evidence from the Yangtze River Economic Belt

Identification and Evaluation of the Polycentric Urban Structure: An Empirical Analysis Based on Multi-Source Big Data Fusion

Identifying and evaluating polycentric urban spatial structure is essential for understanding and optimizing current urban development. In order to accurately identify the urban centers of the Guangdong–Hong Kong–Macao Greater Bay Area (GBA), this study firstly fused nighttime light data, POI data, and population migration data based on wavelet transform, then identified the polycentric spatial structure of the GBA by carrying out cluster and outlier analysis, and evaluated the level of different urban centers byconducting geographical weighted regression analysis. Using data fusion, we identified 4579.81 km² of the urban poly-center area in the GBA, with an identification accuracy of 93.22%. Although the number and spatial extent of the identified urban poly-centers are consistent with the GBA development plan outline, the poly-center level evaluation results are inconsistent with the development plan, which shows there are great differences in actual development levels among different cities in the GBA. By identifying and grading the polycentric spatial structure of the GBA, this study accurately analyzed the current spatial distribution and could provide policy implications for the GBA’s future development and planning.

Polycentric Urbanization and Sustainable Development in China

AbstractThis paper addresses urbanization in the context of China's efforts to meet its commitments regarding the United Nations’ Sustainable Development Goals (SDGs). This paper focuses specifically on governmental policies to promote polycentricity, with multiple urban centers of a similar scale within metropolitan areas, rather than a traditional single, dominant central business district. Polycentric urban forms have the potential to reduce average commuting times, thereby impacting greenhouse gas emissions. Polycentricity may also enhance access to employment and other opportunities for marginalized households. To this end, we examine the nexus between emerging polycentric urbanization patterns in Chinese cities and modes of governance at the national and local levels. Changsha, in Hunan province, is selected as a case study to illuminate the issues. Our analysis shows that fiscal considerations and other national and local governance imperatives can play a crucial role in determining how urbanization evolves. While China is unique in many ways, there are also important commonalities with other countries in the global South that are experiencing rapid urbanization, so the insights generated here may be more broadly applicable.

Estimation of Traffic Emissions in a Polycentric Urban City Based on a Macroscopic Approach

Estimation of Traffic Emissions in a Polycentric Urban City Based on a Macroscopic Approach

Regenerating Hong Kong’s New Towns: Resilience and Collaboration in the Context of Polycentric Urban Development

Hong Kong’s New Towns, since their emergence in the 1960s, have been planned with various strategies aimed at creating self-sufficient communities. External challenges have led to varied successes in achieving this goal, as Hong Kong’s industry, society, and modes of live and work have gradually changed. As the city continues to build new urban areas and connecting infrastructures, its existing New Towns deserve to be re-evaluated, as they can continue to grow and adapt in parallel with Hong Kong’s evolving economic and strategic position with the Greater Bay Area. This article presents a series of urban design strategies for the upgrading of existing New Towns, developed in the context of the Master of Science in Urban Design programme at The Chinese University of Hong Kong. Based on their historic development, current qualities and challenges, and a review of international precedents, theories and policies, four strategic methods for New Town regeneration are discussed. Firstly, we assess the strategic location of Kowloon’s New Territories to develop principal nodes within the polycentric structure of the region. Secondly, we explore strategies for increased economic and employment opportunities, through the promotion of regional innovation systems and entrepreneurialism. Thirdly, the role of public space and placemaking in the upgrading of neighbourhoods and community life is discussed. Finally, we review strategies to enhance the ecological performance of New Towns.

Mapping the Spatial Conditions of Polycentric Urban Development in Europe: An Open‐source Software Tool

Urban polycentricity has become a key concept in urban and regional studies and is increasingly adopted as an organizational framework for conducting empirical research. Within this literature, polycentric urban regions are commonly defined as territories that have multiple, proximately located (sub)centers and are characterized by balanced urban development. However, analytical‐operational frameworks to identify and classify PURs are often ad hoc efforts to answer a specific research question and underlying work is often shelved rather than shared and/or made accessible. As a result, challenges associated with generalizability, reproducibility, and replicability clearly loom large in the urban polycentricity literature. Against this backdrop, this article describes the discrepancy between a rich debate on polycentricity and the paucity of tools enabling the disambiguation and reproducibility of results claimed by various authors around this polysemic concept. We present an online and open tool—PURban—that brings together the major analytical‐operational frameworks and data sets in urban polycentricity research and allows parametrizing key operational choices. To illustrate the tool, we demonstrate how it facilitates the identification, mapping and analysis of degrees of morphological polycentricity in European urban systems. We conclude by reflecting on how this tool can act as a catalyst for future research on urban polycentricity.

Polycentric Urban Development and its Determinants in China: A Geospatial Big Data Perspective

The urban structure of large Chinese cities has been well researched, but a systematic analysis of polycentric urban development and the determinants of subcenter formation across municipal districts in cities at the prefectural level and above (PLACMD) is lacking. Using geospatial big data and spatial analysis methods, we measure the urban spatial structure of all 294 PLACMDs to determine the polycentric urban structure in China and conduct an exploratory regression analysis of 59 PLACMDs (due to data restrictions) to explore the formation of polycentric cities. Our results suggest that using location‐based data allows for a timelier and more accurate center identification of detailed urban structural features than using other data. Each PLACMD in China has at least one center, and polycentricity is currently the most common urban spatial structure. PLACMDs with higher populations are more polycentric. Compared with the results obtained from large American urban areas, our regression results imply that population alone accounts for most of the variation in the polycentric index and that commuting costs provide a weak explanation of the existence of Chinese PLACMDs. Both economic development and agglomeration economics are associated with the polycentric index. In contrast, the topographical features are statistically nonsignificant in the regression model.

Assessing Polycentric Urban Development in Mountainous Cities: The Case of Chongqing Metropolitan Area, China

Mountainous settlements accommodate nearly one tenth of the world’s population. Most mountainous cities have adopted the strategy of polycentric urban development due to an asymmetric geography, which has received little attention from mainstream research. To fill the research gap, we proposed an analytical framework and conducted a multi-dimensional measurement of polycentricity. Taking Chongqing for the case study, this work confirmed that polycentricity is morphological and functional in mountainous cities. Polycentricity is believed to be particularly applicable to mountainous and water-rich landscapes, leading to an appropriate, balanced distribution and the strong multi-directional connectivity of urban nodes. This characteristic may partly result from natural determinism and long-term planning adaptation, complementary to market forces. Policy implications for planning such as avoiding excessive encroachment on natural barriers and increasing functional linkage in newly established subcenters were also proposed.

How Does Polycentric Urban Form Affect Urban Commuting? Quantitative Measurement Using Geographical Big Data of 100 Cities in China

The relationship between polycentric urban form and urban commuting has been widely debated in Western academic circles. However, qualitative and quantitative studies have not reached a unified conclusion. The evolution of urban form in China is remarkably different from that of developed Western countries. Many Chinese cities have begun using polycentric structures as their future development strategies. This study quantitatively measures whether polycentric urban form can improve commuting efficiency in China by using traditional statistics and emerging geographic big data. We use the polycentric index (PI) as the dependent variable and the congestion delay index (CDI) and mean traffic speed (MTS) as the main independent variables. Control variables include urban morphological space compactness (CT), number of private cars per thousand people (PC), number of buses per thousand (PB), urban road area per capita (PUA) and urban population density (PD). Regression models are employed to detect the relationships among the variables. The main research conclusions are as follows: (1) A high degree of PI results in low CDI and fast MTS; (2) a compact spatial form increases the impact of polycentricity on commuting efficiency; (3) maturity road infrastructure is an important measure to promote urban commuting under a polycentric urban form; and (4) the order of effect magnitude of polycentricity on MTS is PD > PC > CT > PUA > PB; on CDI, PD > PC > PB > CT > PUA. The results can be used in examining whether the current polycentric urban pattern planning in China’s cities can effectively improve commuting efficiency. They also provide a reference for the healthy development of China’s urban space and policy formulation of subsequent urban planning.

Continuum Dynamic Traffic Assignment Model for Autonomous Vehicles in a Polycentric Urban City with Environmental Consideration

This paper proposed a continuum dynamic model for autonomous vehicles in a polycentric urban city by considering the environment impact of traffic emission. The model assumes that homogeneous autonomous vehicles are continuously distributed over the urban areas which tend to choose a path to minimize their total travel cost from origin to destination. To describe the path choice behavior of travelers, we presented the continuum dynamic traffic assignment model which consists of a two-dimensional hyperbolic system of nonlinear conservation laws with source terms and an Eikonal-type equation. The elastic demand is considered using a function which associating each copy of flow with its total instantaneous travel cost. For the environmental impacts, here we consider the influence of CO emission and include the cost of emission into the actual transportation cost. A solution algorithm for the model is designed as a cell-centered finite volume method for conservation law equations and a fast sweeping method for Eikonal-type equations on unstructured grids. Numerical examples are given to demonstrate the model and the proposed solution algorithm. Further, the results of the travel cost considering CO emissions and not considering CO emissions are compared.

Does the Polycentric Urban Region Contribute to Economic Performance? The Case of Korea

This study aims to explore whether and to what extent two types of polycentricity, morphological and functional, affect the level of urban economic performance. In the analysis, it is found that morphological polycentricity is positively associated with the level of labor productivity whereas functional polycentricity is negatively related to it. In the context of the Korean urban system, characterized by the domination of a few cities and high levels of population density, regions which are more morphologically polycentric and functionally monocentric are likely to have higher labor productivity. These results reflect the processes of agglomeration economies and their impact on urban dynamics. This study contributes to the debates on the impacts of polycentricity on economic performance by examining this relationship in the East Asian context, not in Europe or America, and by distinguishing between effects of two types of polycentricity.

Ex Post Impact Assessment of Master Plans—The Case of Shenzhen in Shaping a Polycentric Urban Structure

This study of ex post impact assessment aims to review the lessons learned from the implementation of previous master plans in the case study city of Shenzhen (China) in order to provide evidence-based input for the possible integration of impact assessment in future master planning in Shenzhen and other world cities, particularly in developing and emerging countries. The paper uses GIS data to derive maps for the visualization of spatial developmental patterns with complementary quantitative analysis for the spatial-temporal impact assessment. The ex post impact assessment shows that the master plans of Shenzhen have successfully guided urban development towards a polycentric spatial structure. Regarding the data used in the study, Global Human Settlement Layer (GSHL) is a valuable dataset that is generally suited to assessing the urban development pattern. The time series mapping of growth in built-up areas as well as population and built-up intensity mapping based on time specific categorization supplemented by the quantitative assessment of high urban concentrations (hUCs) based on time specific thresholding allows the identification of development patterns over a long period of time.

Beyond Polycentricity: Does Stronger Integration Between Cities in Polycentric Urban Regions Improve Performance?

AbstractA quarter of the European population lives in ‘polycentric urban regions’ (PURs): clusters of historically and administratively distinct but proximate and well‐connected cities of relatively similar size. This paper explores whether tighter integration can increase agglomeration benefits at the PUR‐level. We provide the first comprehensive list of European PURs (117 in total), establish their level of functional, institutional and cultural integration and measure whether this affects their performance. ‘Performance’ is defined as the extent to which urbanisation economies have developed, proxied by the presence of metropolitan functions. In this first‐ever cross‐sectional analysis of PURs we find that while there is evidence for all dimensions of integration having a positive effect, particularly functional integration has great significance. Regarding institutional integration, it appears that having some form of metropolitan co‐operation is more important than its exact shape. Theoretically, our results substantiate the assumption that networks may substitute for proximity.

Dynamic Continuum Model with Elastic Demand for a Polycentric Urban City

This paper presents the development of a macroscopic dynamic traffic assignment model for continuum transportation systems with elastic demand. A reactive dynamic user equilibrium model is extended to simulate network equilibrium problems for an urban area with multiple central business districts (CBDs). Each copy of traffic flow reactively makes route choice decisions to minimize the total travel cost from origin to destination, based on instantaneous traffic information from a radio broadcasting service or route guidance system. The elastic demand function for each copy of flow is associated with its total instantaneous travel cost. The model is solved by a cell-centered finite volume method for conservation law equations and a fast sweeping method for Eikonal-type equations on unstructured grids. Numerical experiments for an urban traffic network with two CBDs are presented to verify the rationality of the model and the validity of the numerical method. The numerical results indicate that the model captures some macroscopic characteristics of two copies of flow interacting in time-varying urban transportation systems, e.g., the spatial distributions of the flow density and flux and the path choice behavior in response to elastic demand, and can describe traffic equilibrium phenomena, such as self-organization and traffic congestion build-up and dissipation.