Mapping Urban Accessibility in Data Scarce Contexts Using Space Syntax and Location-Based Methods

Jose Morales,Javier Morales,Johannes Flacke,Jaap Zevenbergen

doi:10.1007/s12061-017-9239-1

Abstract

Data scarcity is still a common barrier to adequately understanding urban access in Global South countries. Widely used location-based methods address the traditional definition of accessibility as the easiness to reach land-uses by means of available mobility modes. Space Syntax instead analyses accessibility as network centrality focusing only on the topological and geometric properties of urban layouts, making it comparatively less data-intense. However, the interpretation of its outputs is limited to its own theory. Knowledge is missing on how such metrics are comparable to the metrics produced by location-based methods. The objective of the research was to compare both approaches for mapping urban accessibility in two cities in Guatemala. Our hypothesis tested the assumption that Space Syntax metrics could consistently reflect accessibility conditions that so far have only been measured by location-based methods. We proposed an approach using volunteered geo-information and produced accessibility maps following both approaches that were then compared using Pearson correlations. Space Syntax metrics at low and high radii are consistently correlated with location-based access to land uses that reflect location quality at neighbourhood and city-wide scale correspondingly. Space Syntax metrics at lower radii reflect time-based access restrictions either posed in the location-based analyses or by reduced accessibility by public transport. The hypothesis acceptance, p < 0.01, expands the scope of accessibility knowledge derivable from limited data availability using Space Syntax, which is relevant for its applicability in data-scarce contexts by planners and researchers in the Global South. Rather than replacing location-based methods Space Syntax offers an important complementary measure to geographical accessibility. This having been said, Space Syntax could contribute to early-stage planning by gaining overall insights into patterns of urban access.

Highlights

Understanding urban accessibility is fundamental for land use and transport planning (Curtis and Scheurer 2010; Geurs and Van Wee 2004; Curl et al 2011), as it is one of the key aspects for agglomeration economies, economic growth, and quality of life (Ahlström et al 2011; Kourtit et al 2015; Rietveld 2015)
We developed a methodological framework for analysing accessibility using Space Syntax (SSx) and location-based methods
The results do not explain directionality of the causal relation between geometrical and geographic accessibility, but it is logical to think that in Global South cities with weak land-use policies, geometric accessibility influences a location process where various land uses seek to benefit from reachable locations and exposure to movement

Summary

Introduction

Understanding urban accessibility is fundamental for land use and transport planning (Curtis and Scheurer 2010; Geurs and Van Wee 2004; Curl et al 2011), as it is one of the key aspects for agglomeration economies, economic growth, and quality of life (Ahlström et al 2011; Kourtit et al 2015; Rietveld 2015). Geographic accessibility is the most common one and is defined as the opportunity at origin to reach a destination, or vice-versa, given the impedance between both locations (Curl et al 2011; Handy and Niemeier 1997; Batty 2009; Geurs and Van Wee 2004; Ingram 1971; Albacete et al 2015). The combined effect of land use distribution and infrastructure components at a given location determines geographic accessibility (Geurs and van Eck 2001). Locationbased measurements have been the preferred methods to analyse geographic accessibility (Geurs and van Eck 2001; Curl et al 2011). Common problems are incomplete or outdated data sets as resources might not be available for periodic collection and maintenance

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Conclusion