A pluralistic approach to defining and measuring urban sprawl - Urban Remote Sensing: Monitoring, Synthesis and Modeling in the Urban Environment - page 157

12.1 Introduction

belief that despite the constant refrain that there is no consen-
sus on sprawl, there is enough agreement to move forward in
quantifying relevant forms of urban spatial development. To this
we add two caveats. First, sprawl researchers must be explicit
in their qualitative definition of sprawl and use quantitative
variables that complement their definition. Second, since differ-
ent variables may yield different results, a pluralistic approach
should be adopted which allows for the possibility that sprawl
is a multifaceted phenomenon that appears differently on the
landscape depending on how, where and when it is measured.
We allow the researcher and/or end-user to determine which
variables are relevant to their location-specific research and their
own sprawl definitions. We conclude our overview of sprawl
with a short historical narrative of urban spatial development
that was/is considered sprawl.
Next, we provide an extended list of spatial variables for
measuring the state of sprawl and associated processes and
explore how these variables have been applied empirically. We
taxonomize the variables and rank them according to criteria for
what constitutes a good measure and suggest when and where
the application of each variable would be recommended. We
conclude by comparing results of four macro-studies of sprawl
in US metropolitan regions to elucidate how the use of different
measures produces similar or different results.
While we direct our narrative to remote sensing experts, we
emphasize that ''sprawl'' is often considered as much a socio-
economic phenomenon as a physical one. As such, the remote
sensing literature is somewhat limited with regard to sprawl
discourse, primarily measuring certain physical manifestations
of urban development, like building density, time series of urban
growth, and geometric parameters of urban form (Sutton, 2003;
Hasse, 2007; Irwin and Bockstael, 2008; Bhatta, Saraswati and
Bandyopadhyay, 2010). We note that all of these, when combined
with geographically-specific socioeconomic and demographic
data (e.g., Martinuzzi, Gould and Ramos Gonzalez, 2007), greatly
expand our options for measuring sprawl. We assume here
that professionals employing remote sensing would benefit by
knowing what variables would be useful for them to quantify,
and after doing so, provide the results to urban planners, the
policy-making community and other stakeholders.

... I know it when I see it

Justice Potter Stewart, 1964 1

Justice Stewart's frequently quoted statement was not a reference
to urban sprawl, but considering the widespread debate about its
very definition, it is particularly appropriate and widely used in
this context. Urban sprawl is indeed something that many people
seem to recognize and have an opinion about, but when it comes
to quantifying its dimensions, we become less certain regarding
what we are measuring on the ground.
The term ''urban sprawl'' was first coined by Buttenheim
and Cornick (1938), and its use became common throughout
the latter half of the 20th century. Sprawl has been used as the
descriptive, yet generic, term of choice to describe a variety of
urban development forms that shared low density of buildings
and population as a unifying trait. These types of urban spatial
development played a predominant role in modern urban form
in North America and Europe (Glaeser and Kahn, 2004) and
a contentious debate regarding their desirability erupted and
continues through the present (Ewing, 1997, 2008; Gordon and
Richardson, 1997, 2000).
Despite broad interest that developed around the issue of
urban sprawl, establishing a clear and unambiguous definition
has proven to be an elusive task (Chin, 2002; Hasse and Lathrop,
2003a; Wolman et al ., 2005; Hasse, 2007). Commentators on
sprawl refer to a broad array of defining characteristics (Hess
et al ., 2001; Johnson, 2001; Ewing Pendall and Chen, 2002;
Wolman et al ., 2005; Cutsinger and Galster, 2006; Hasse, 2007).
Galster and colleagues (2001) write that the term ''urban sprawl''
became a metaphor used alternatively to describe (or imply)
the patterns, processes, causes and/or consequences of particular
urban spatial development patterns. A concise definition has
been further muddled because the term is ultimately a cultural
construct (Bruegmann, 2005). Therefore, cultural milieu, ideol-
ogy, and personal experience are intimately linked to how people
define sprawl. The lack of a single definition has logically led to
difficulty in establishing a unified methodology for measuring
the phenomenon; after all, how can we measure what we don't
know we're measuring (Burchell et al ., 1998; Malpezzi, 1999;
Torrens and Alberti, 2000; Galster et al ., 2001; Johnson, 2001;
Ewing, Pendall and Chen, 2002)?
Most scholars and practitioners agree that a first step towards
defining sprawl is to quantify various characteristics of urban
spatial development and the dynamics guiding them. Once this
is done, scholars, policy-makers and others can then debate the
desirability of such phenomena and discuss, if needed, policies
to address them. Therefore recent research efforts have focused
on establishing and measuring quantifiable variables that capture
various characteristics of urban spatial development.
We begin this chapter by integrating several definitions of
sprawl derived from a comprehensive survey of the academic
and professional literature in order to extract quantifiable spa-
tial characteristics recurring throughout the literature. It is our

12.2 The diversity of
definitions of sprawl

Several syntheses of sprawl definitions exist in the literature
(Burchell et al ., 1998; Galster et al ., 2001; Hess et al ., 2001;
Malpezzi and Guo, 2001; Chin, 2002; Ewing, 2008; Frenkel
and Ashkenazi, 2008a, 2008b; Torrens, 2008). According to
these sources, urban sprawl has been defined primarily in three
ways: (1) definitions relating to describing a physical and spa-
tial phenomenon of urban spatial development (qualitatively
and quantitatively); (2) definitions that focus on the purported
social, economic and/or ecological consequences of the phe-
nomenon (described in various ways), and by extension, by
normative desires to avoid perceived undesirable urban spatial
development patterns, and; (3) definitions focusing on particu-
lar socio-economic trends that lead to particular urban spatial

1 Jacobellis v. Ohio (378 US 184; 1964); available from http://caselaw.lp.findlaw.com/
scripts/getcase.pl?court = USandvol = 378andinvol = 184 (accessed 15 November

2010).