2.3. Funtional objects

Figure 2.9. Comparison of specifications for two functional approaches of cities

Comparison of specifications for two functional approaches of cities

source: H. Mathian, A. Pavard, may 2012


2.3.1. FUA_Igeat

The Functional Urban Areas defined by IGEAT (FUA_Igeat) are based on the analysis of commuting patterns towards morphological urban cores in 2000 (Peeters, 2011):

  • The urban cores correspond to all the MUA over 20 000 inhabitants (see section MUA).

  • The exterior ring of a FUA is constructed by selecting the municipalities (LAU2) where more than 10% of the economically active population works in MUA/urban cores. Each municipality can only be associated to one MUA. As a consequence, if one of these municipalities depends on several MUA, it is linked to the MUA which registers the highest commuting rate. In case of equality in commuting rates, it is linked to the most populated MUA.

  • In general, each FUA is structured around one MUA, except in few cases: if two MUA send to each other important commuting flows (unspecified level), they are aggregated into the same FUA.

  • The exterior ring of a FUA is a group of touching municipalities, without "holes". If the exterior ring of the FUA is fragmented into several parts, especially on its outskirts, only the main and largest part is kept, except in the case where fragmentation is caused by geographical specifities (like islands, for instance). If some municipalities are enclosed by other municipalities belonging to the exterior ring of a FUA, they are attributed to the same FUA, so that the holes are filled.

This database contains 1530 urban objects that cover 29 countries (EU27 (1 January 2007 - 30 June 2013) plus Norway and Switzerland). The majority of the issues raised by this database are described by D. Peeters (2011) the main issues are related to missing data (no comuters data provided for Poland or Romania, no transnational commuters data in general) or to inconsistencies (errors in active population data in Germany). Furthermore, the population data provided for the smallest FUA has to be interpreted with caution.

The following spreadsheet contains the complete description of the FUA classification: nomenclature.xls.

Figure 2.10. FUA_Igeat delineations (2012)

FUA_Igeat delineations (2012)

source: UMR Géographie-cités, 2013


2.3.2. LUZ harmonized

The Larger Urban Zones harmonized correspond to the new definition of cities for the latest Urban Audit and were created by the consortium Eurostat, Urban Audit and OECD (Djikstra, Poelman, 2012). In the 2012 version (reference year 2006), this definition is based on the construction of a commuting zone around a core city:

  • The urban core (city) lies on two criteria: a minimal desity threshold ans a minimal population threshold. It is defined through three main steps: (1) High density population area is first identified by selecting grid cell over 1500 inh./km2 and by aggregating contiguous high-density cells; (2) Only the clusters larger than 50 000 inhabitants are retained as urban cores ; (3) Those cores are adjusted to LAU2 delineations: all the LAU2 with at least 50% of their population inside the urban core are retained and form the urban core.

  • The commuting zone around this urban core is identified by using commuting patterns: it is composed by all the LAU2 where more than 15% of their employed resident population work in the urban core. Then, all the LAU2 which are enclosed within this functional area are included and all the non-contiguous LAU2 are dropped.

In the version that should be soon available on the OECD web site, the database contains 695 urban objects that cover 31 countries (EU28 plus Norway, Switzerland and Iceland).

In the previous version of LUZ produced by the Urban audit (LUZ 2004), the LUZ deineation was based on the collection of national delineations depending on different conceptual approaches of cities and different sources (Bretagnolle et al., 2011). Only 12 countries had LUZ definitions based on commuters (with various minimal commuting thresholds). The new database should ensure better harmonized results. For the time being, the LUZ harmonized protocol has been adopted by 16 countries and 4 other countries have preferred other definitions based on commuters.

Figure 2.11. LUZ harmonized delineations (2012)

LUZ harmonized delineations (2012)

source: UMR Géographie-cités, 2013


2.3.3. Comparison between FUA_Igeat and LUZ harmonized

Figure 2.12. Comparison between the 50 most populated FUA_Igeat and corresponding LUZ harmonized

Comparison between the 50 most populated FUA_Igeat and corresponding LUZ harmonized

source: UMR Géographie-cités, 2013