An evolutionary approach to the delineation of functional areas based on travel-to-work flows

Abstract

This paper presents a new approach to the delineation of local labor markets based on evolutionary computation. The aim of the exercise is the division of a given territory into functional regions based on travel-to-work flows. Such regions are defined so that a high degree of inter-regional separation and of intra-regional integration in both cases in terms of commuting flows is guaranteed. Additional requirements include the absence of overlapping between delineated regions and the exhaustive coverage of the whole territory. The procedure is based on the maximization of a fitness function that measures aggregate intra-region interaction under constraints of inter-region separation and minimum size. In the experimentation stage two variations of the fitness function are used, and the process is also applied as a final stage for the optimization of the results from one of the most successful existing methods, that used by the British authorities for the delineation of Travel-to-Work Areas (TTWAs). The empirical exercise is conducted using real data for a sufficiently large territory which is considered to be representative given the density and variety of travel -to-work patters that it embraces. The paper includes the quantitative comparison with alternative traditional methods, the assessment of the performance of the set of operators which has been specifically designed to handle the regionalization problem, and the evaluation of the conver gence process. The robustness of the solutions, something crucial in a research and policy-making context, is also discussed in the paper.

Delineating zones to increase geographical detail in individual response data files: An application to the Spanish 2011 Census of population

“…To assess the degree of commuting interaction between a pair of clusters or BSUs, we use the interaction index proposed by Flórez-Revuelta et al (2008), a generalisation of the index used in the TTWA method (Coombes et al, 1986). This indicator takes into account the commuting flows in both directions as well as the relative size of both areas to weight the flows between them.…”

“…Although international experience is quite extensive (see, for example, Casado-Díaz and Chakraborty et al (2013) and Alonso et al (2015). Flórez-Revuelta et al (2008) proposed a grouping evolutionary algorithm (a general-purpose optimisation technique used in Artificial Intelligence, with genetic operators specifically designed to fit grouping problems) in order to optimise a fitness function that measures the interaction within LMAs, subject to reach certain minimum self-containment and population thresholds. Their fitness function is based on the interaction index (originally proposed by Smart, 1974) that is used to define the official Travel-to-Work Areas (TTWAs) in the UK (Coombes et al, 1986;Coombes and Bond, 2008;ONS, 2015) and the Sistemi Locali del Lavoro in Italy (ISTAT, 1997;2005;2014), their local version of LMAs.…”

“…Their fitness function is based on the interaction index (originally proposed by Smart, 1974) that is used to define the official Travel-to-Work Areas (TTWAs) in the UK (Coombes et al, 1986;Coombes and Bond, 2008;ONS, 2015) and the Sistemi Locali del Lavoro in Italy (ISTAT, 1997;2005;2014), their local version of LMAs. Martínez-Bernabeu et al (2012) further improved upon the work by Flórez-Revuelta et al (2008) by designing renovated search operators that allow for higher quality results and a reduction in computational costs. Alonso et al (2015) propose and exemplify a delineation scheme based on these grouping evolutionary algorithms.…”

“…Moreover, the expected interaction value in the null model increases with the size of the territory under analysis, while the actual LMAs for a given region should not depend on whether or not some other unrelated regions are included in the analysis. These drawbacks of the modularity function lead to our preference for the interaction function of Flórez-Revuelta et al (2008), as well as their general methodology, which has been found to produce better results than the widely-applied TTWAs method, in terms of the number of identified LMAs and cohesion values for the same levels of minimum selfcontainment, while the works based on modularity have not been compared with alternative approaches.…”

A Multistage Agglomerative Approach for Defining Functional Regions of the Czech Republic: The Use of 2001 Commuting Data/ Vícestupňový aglomerační přístup k vymezení funkčních regionů České republiky: využití údajů o dojížďce z roku 2001

“…The third, multistage or rule-based approach, which is used in this paper, was proposed by the research group at CURDS 1986;Coombes, Bond, 2008;Coombes, 2010), and became probably the most successful and acknowledged approach to the functional regional taxonomy of several territories. Apart from the above-mentioned works that concerned the U.K., this approach was applied in Italy (Sforzi [ed.], 1997), Slovakia (Bezák, 2000;Halás et al, 2014), Spain (Casado-Díaz, 2000;Flórez-Revuelta et al, 2008), New Zealand (Papps, Newell, 2002;Newell, Perry, 2005), Belgium (Persyn, Torfs, 2011), Poland (Gruchociak, 2012), and in the Czech Republic (Klapka et al, 2013b;Tonev, 2013). The principle used in these methods lies in the definition of a set of rules that are applied in several stages and determine the results of the analyses.…”