Measuring polycentricity via network flows, spatial interaction and percolation

Somwrita Sarkar, Hao Wu and David Levinson
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Somwrita Sarkar: School of Architecture, Design and Planning, The University of Sydney, Australia
Hao Wu: School of Civil Engineering, Faculty of Engineering and Information Technologies, The University of Sydney, Australia

Urban Studies, 2020, vol. 57, issue 12, 2402-2422

Abstract: Polycentricity, or the number of central urban places, is commonly measured by location-based metrics (e.g. employment density/total number of workers, above a threshold). While these metrics are good indicators of location ‘centricity’, results are sensitive to threshold choice. We consider the alternative idea that a centre’s status depends on its connectivity to other locations through trip inflows/outflows: this is inherently a network rather than place idea. Three flow and network-based centricity metrics for measuring metropolitan area polycentricity using journey-to-work data are presented: (a) trip-based; (b) density-based; and (c) accessibility-based. Using these measures, polycentricity is computed and rank-centricity distributions are plotted to test Zipf-like or Christaller-like behaviours. Further, a percolation theory framework is proposed for the full origin–destination matrix, where trip flows are used as a thresholding parameter to count the number of sub-centres. Trip flows prove to be an effective measure to count and hierarchically organise metropolitan areas and sub-centres, tackling the arbitrariness of defining any threshold on employment statistics to count sub-centres. Applications on data from the Greater Sydney region show that the proposed framework helps to characterise polycentricity and sub-regional organisation more robustly, and provide unexpected insights into the connections between land use, labour market organisation, transport and urban structure.

Keywords: accessibility; Greater Sydney Metropolitan Area; journey-to-work; origin–destination flows; networks; percolation; polycentricity; å ¯å Šæ€§; 大悉尼都市区; 通勤; å§‹å ‘åœ°-ç›®çš„åœ°æµ é‡; 网络; 渗é€; 多中心性 (search for similar items in EconPapers)
Date: 2020
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Citations: View citations in EconPapers (9)

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Persistent link: https://EconPapers.repec.org/RePEc:sae:urbstu:v:57:y:2020:i:12:p:2402-2422

DOI: 10.1177/0042098019832517

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