A scenario for the new official French urban areas zoning Marie-Pierre de Bellefon Paper prepared for the 16th Conference of IAOS OECD Headquarters, Paris, France, 19-21 September 2018 Session 3F, Thursday, 20/09, 10h30: Urbanisation and sustainable city Marie-Pierre de Bellefon [email protected] INSEE - French National Institute for Statistics and Economic Research A scenario for the new official French urban areas zoning Prepared for the 16th Conference of the International Association of Official Statisticians (IAOS) OECD Headquarters, Paris, France, 19-21 September 2018 This Working Paper should not be reported as representing the views of INSEE. The views expressed are those of the author(s). ABSTRACT How to harmonize the definition of French urban areas with international standards, while still precisely describing France’s unique territorial characteristics? Answering this question is the purpose of this article, which proposes a scenario for a new French urban areas zoning. Our methodology extends OECD’s Functional Urban Areas definition to analyse thoroughly the French urban system. It distinguishes two categories of Urban Areas and allows to detect secondary centres and analyse their interaction with main centres. Keywords: urban area definition, French zoning, functional areas, monocentric model, degree of urbanisation. 1. INTRODUCTION As defined by the French National Institute for Statistics and Economic Research (INSEE), statistical territorial zoning aim to go beyond the logic of administrative zoning, in order to have zoning adapted to economic and social issues. The economist Gilles Duranton (Duranton, 2015) highlights four arguments justifying the interest of statistical zoning. Historically, when cities expanded, they used to integrate neighbouring municipalities. In many countries, this process has stopped, mainly because of administrative, fiscal or political reasons. Cities’ administrative borders thus now delineate only the historical urban core and are not representative of the whole urban extension. In response to this finding, INSEE defined, as early as 1954, statistical Urban Units. Urban Unit’s definition has not changed since 1962: it is based on building’s continuity (no more than 200 meters between buildings), and adds a total population criteria (more than 2000 inhabitants). This morphological definition, although useful to determine cities physical extension, soon appeared insufficient to analyse the intertwining of rural housing and the urban way of life that increased with the parallel development of automobiles and the single-family homes (Le Jeannic, 1988). Indeed, the second argument in favour of statistical zoning, is the need of a territorial breakdown adapted to the study of the interacting network that commuters, companies and individuals form around cities. This network is associated with all kinds of economic ties between neighbouring municipalities. Since administrative units such as municipalities most often do not constitute autonomous functional units, an economic shock or a public policy targeting a given municipality can have diffuse spillover effects on neighbouring municipalities. Considering how difficult it is to precisely anticipate and evaluate these spillovers effects, it is easier and more effective that the public policy directly targets a coherent economic unit. Lastly, confining a city's analysis to economic and social parameters measured within its administrative boundary can present it in an unfavourable light and have a negative influence on investors' decisions. Parr, 2007 gives the example of former industrial cities like Nottingham, whose performances in term of unemployment rate, education level and public health clearly improve when considering the whole urban area instead of the administrative city. Taking all these considerations into account, Insee proposed in 1962 a functional definition of cities, complementary to that of Urban Units. This definition evolved until the actual version, published in 2010 and entitled “Zoning into Urban Areas”. This zoning aims at delineating the city’s influence area. Urban cores are defined as Urban Units with more than 1500 workers, and their periphery consists in all municipalities sending more than 40% of their workers to the core or to a municipality already aggregated to a core. In line with recent developments in the literature on the definition of urban areas (Dijkstra, 2018; Henderson, 2018; Veneri, 2018), Insee has initiated a complete redesign of its urban area zoning. This article presents and justifies a new zoning methodology, which aims at addressing the multiple challenges faced by a National Statistical Institute when trying to define statistical urban areas. The first of these challenges is to define what is to be measured under the term of “city’s area of influence”, and which variables are best suited to this objective. Choices must be made such as whether a urban core is predetermined – and, if so, thanks to which criteria - or whether it is endogeneoulsy determined by commuting patterns. The advantages and drawbacks of using commuting data as a measure of city’s influence on its environment also have to be assessed. Lastly, this reflection must take into account the positioning of Urban Areas in relation to other Insee study zoning. Urban economics theory helps us to answer these questions. Our second challenge is to reconcile two requirements. One of the main objectives of Insee’s redesign of Urban Areas is to make them coherent with Eurostat-OECD’s Functional Areas, whose use is spreading internationally. Yet Functional Areas are defined for the purpose of making some international comparisons; they do not describe the French urban system with the level of accuracy expected by French users. We therefore propose some extensions of the international method that allow a more thorough description of the national territory: two categories of Urban Areas are distinguished, and secondary centres are identified, while the method remains simple enough to be quickly understood by the zoning’s users. Lastly, one important issue of study zoning published by National Statistical Institutes is their comparability over time. Our methodology thus allows to proceed to some backward projection, and therefore to study the evolution of the French periurbanization, the intra-urban coherence, and the validity of some of the major predictions of regional and urban economics theory. Although the outlines of the methodology are based on principles published by Eurostat and the OECD, the efforts to harmonize precise description of the national territory and international comparability contribute to the literature about the definition of urban areas. The identification of secondary centers also gives a novel insight into the relations between systems of cities. Our hope is that this methodology can be useful to other National Statistical Institute facing the same challenges. The remainder of this paper is organized as follows. Section 2 situates the current French Urban Areas zoning among an international comparison of zoning practices. Section 3 provides some theoretical background for the new scenario and the concrete methodological consequences. Section 4 presents the first results. Lastly, section 5 concludes. 2. FRENCH AND INTERNATIONAL CONTEXT 2.1 THE FRENCH URBANIZATION CONTEXT In order to propose a zoning methodology adapted to the French specificities, it is important to begin with an analysis of the French urbanization context. During the last quarter of the 20th century, populations have increasingly gathered around large urban centres (Roux, 2008). Charmes, 2015 describes this sub-urbanisation movement, not as an urban sprawl, but as a “fragmentation of the city”. Indeed, peri-urban population work in a big metropolis, but distinguishes itself from suburban population by the fact that it crosses green spaces before arriving at its pavilion complex. This phenomenon of “leap frog development” is much more marked in France than in the United States or in Great Britain. It is accomplished in two steps: first the central city’s growth increase the demand for housing in outlying villages. This demand is welcomed by local mayors, which see it as a way to revitalize their municipality. Then, when newcomers become a majority, the desire to preserve the living environment dominates and the municipality blocks the extension of its urban spaces. Other municipalities, further from the central city, then engage in the early stages of peri-urbanization. Opinions differ as to the continuation of this phenomenon. Some argue that commuting costs could restrict the peri-urbanization; others argue that 5 secondary centres emerge, which become relays for the peri-urban extension. According to Charmes, secondary centres are only growth drivers for the major pole, and links between them remain an exception. Veltz, 2010 speaks of a “rurban nebula” which attracts only activities which have been rejected outside of the heart of the urban agglomeration because of their high land consumption or their low added value. These areas maintain a strong dependence on the main pole. One of the objectives of the zoning into Urban Areas is to help researchers to analyse the French Urbanization phenomenon, and to have access to concrete elements to help them to validate or to reject some of the above cited hypothesis. The analysis of secondary centres, their relations with the main centre and their own attractiveness seems to be