Measuring urban form: Overcoming terminological inconsistencies for a quantitative and comprehensive morphologic analysis of cities

Abstract

Unprecedented urbanisation processes characterise the Great Acceleration, urging urban researchers to make sense of data analysis in support of evidence-based and large-scale decision-making. Urban morphologists are no exception since the impact of urban form on fundamental natural and social patterns (equity, prosperity and resource consumption’s efficiency) is now fully acknowledged. However, urban morphology is still far from offering a comprehensive and reliable framework for quantitative analysis. Despite remarkable progress since its emergence in the late 1950s, the discipline still exhibits significant terminological inconsistencies with regards to the definition of the fundamental components of urban form, which prevents the establishment of objective models for measuring it. In this article, we present a study of existing methods for measuring urban form, with a focus on terminological inconsistencies, and propose a systematic and comprehensive framework to classify urban form characters, where ‘urban form character’ stands for a characteristic (or feature) of one kind of urban form that distinguishes it from another kind. In particular, we introduce the Index of Elements that allows for a univocal and non-interpretive description of urban form characters. Based on such Index of Elements, we develop a systematic classification of urban form according to six categories (dimension, shape, spatial distribution, intensity, connectivity and diversity) and three conceptual scales (small, medium, large) based on two definitions of scale (extent and grain). This framework is then applied to identify and organise the urban form characters adopted in available literature to date. The resulting classification of urban form characters reveals clear gaps in existing research, in particular, in relation to the spatial distribution and diversity characters. The proposed framework reduces the current inconsistencies of urban morphology research, paving the way to enhanced methods of urban form systematic and quantitative analysis at a global scale.

Land Consumption and Land Take: Enhancing Conceptual Clarity for Evaluating Spatial Governance in the EU Context

“…Promising advances have been made in using new global datasets, tools, and maps, specifically those subsumed under the header "Global Human Settlement Layer, GHSL" [2,16,29,46]. However, there is no consensus yet on how to define the exact geographic boundaries of urban land and this poses a major challenge for assessing LCR [22,47].…”

Off the Grid…and Back Again?

“…Typical quantitative analyses of urban form measure street networks in terms of density, connectivity, and block lengths or areas (Marshall, 2004;Song and Knaap, 2004;Clifton et al, 2008;Song et al, 2013;Porta et al, 2014;Knight and Marshall, 2015;Boeing, 2020;Fleischmann et al, 2020), all of which are operationalized in this study. Once the street network models have been constructed and the census data downloaded, several tract-level indicators are calculated: intersection density, average street segment length, average node degree, node elevation interquartile range (IQR) (a proxy for hilliness; i.e., how much variation exists in a tract's elevation), the proportion of nodes that are four-way intersections, the proportion of nodes that are dead-ends, and whether a tract is urban or not (i.e., population density ≥1,000 persons per square mile, following Census Bureau convention).…”

Climate Adaptation Plans in the Context of Coastal Settlements: The Case of Portugal

“…Urban Morphometrics (UMM), the quantitative science of urban form, offers a relatively new way of characterising different urban form patterns [25,26]. UMM employs measurable morphometric characters (or urban form characters) [27] to describe the shape and configuration of individual elements of urban form in a way that is automatised [28], hence enabling large-scale and inherently unbiased studies, as measuring algorithms are applied consistently across the whole study area.…”

“…The morphometric analysis leading to the classification of individual cases consists of three phases. The first involves the measurement of 32 primary morphometric characters partially extracted from the Table of Urban Form Characters [27] and partially designed for the purpose of the analysis of seashore streets and their configuration with respect to the available data layers. The second phase collates all elements pertaining to each case and uses them to describe each of the cases as a whole, using case-level values representing the statistical distribution of each measured primary character.…”

“…Morphometric characters used to characterise selected case studies. The name of each character is composed of its index and element [27]. However, because these characters describe individual elements of urban form, they are then aggregated to represent the selected cases as a whole.…”