Until about the end of WWII, the territorial organization of the economy could be expressed along a very strong center-periphery gradient, with industries and services concentrated in cities while the countryside supplied agricultural products. Since the industrial revolution, industrial regions had emerged essentially in mining regions which perturbed this very simple scheme, but without fundamentally modifying it. In the first half of the 20th century, with the advent of mass transportation and of the individual car, the residential functions started to deconcentrate and residential suburbs developed. However, as a general rule, most non-agricultural economic functions remained tightly attached to the city core and its immediate surroundings, and with them their jobs. These structures were accounted for by various theoretical models, of which the Von Thunen land-rent model family, the Weber models of industrial localization and regional specialization, and the Christaller model of hierarchical city networks were the most prominent. However, since 1945, those jobs have seen their territorial distribution shift. First, the importance of agriculture dwindled, to the profit first of industrial activities, then of services. Land-hungry activities, such as the industry and logistical activities vacated the urban centers in search for ample space, which they generally found in suburban settings under the guise of industrial zones. But they weren't alone at deconcentrating. Retail and personal services tended to follow their customers in the suburbs. During the last quarter of the 20th century, selected suburbs evolved from purely residential or industrial functions to more complete economic ones, integrating retail, high tech and professional services. By 1990, the phenomenon was largely recognized in North America, where those job-intensive suburbs were nicknamed edge cities. Empirical studies showed convincingly that the same patterns of job and functional deconcentration were found in the whole world and especially in western countries. Job suburbanization is contemporary with major spatial and functional economical upheavals. The economy, for instance, evolved from the fordist integrated economical model dominated by very large companies internalizing most of their functions in a vertical, hierarchical relationship pattern to a post-fordist disintegrated model where companies concentrate on their core competencies and subcontract in a horizontal, contractual manner their non-core needs. Economical spatial deconcentration is also contemporary with the current version of globalization, materialized by the emergence of global cities and metropolises which keep constant communication flow between themselves, in a horizontal manner, and which are less and less dependent on their hinterland for their economical survival and development. Likewise, the economy becomes more and more informational, relying on knowledge, immaterial services, instant worldwide communication, and the production of sophisticated products for which worldwide shipping costs became negligible, and for which the location needs shifted from access to markets to access to qualified workers. While globalization, metropolization and the post-fordist economical transition have been thoroughly studied, job suburbanization has not been the focus of such an interest from the scientific community. Consequently, we lack empirical evidence and theoretical advances which would help us to better understand how the economy spatially evolved since 1945 and where the world is heading if the trends seen since 1945 are maintained. The prime goal of this work is to provide a better understanding of the way the economy spatially evolved at the intra-metropolitan scale, based on the example of Switzerland, a fairly exemplary western country. The work is divided in three major parts – an introductory one, an empirical one, and a inferential one. The core hypothesis of this work is that as the individual car became ubiquitous, proximal relations were progressively supplanted by accessibility relations. We surmise that job distributions and their evolution can be explained by accessibility patterns and change, which are in turn dependent on a number of factors – the population distribution, the structure and state of the road network, the state of the car technology, and the time commuters are ready to travel to go to work. The first three chapters aim at defining our object of study in chapter 1, to give an understanding of the country on which we will be working and of the data at our disposal in chapter 2, and a working definition of what constitutes a job center in chapter 3, where major distinctions between urban, mixed, suburban, exurban, touristic centers and edgeless space are introduced which accompanies us for the rest of the work. The next four chapters constitute the empirical part of the work. Chapter 4 seeks at describing as precisely as possible the territorial evolution of the Swiss economy since WWII, studying it at nine different points in time from 1939 to 2008. Chapter 5 takes a long-term view of the same series of data and seeks to detect, describe and explain the trends which are unearthed by this larger view. Chapter 6 concentrates on the latter half of the period under review and studies the distributions along more precise branch divisions, as well as miscellaneous other classifications according to added value and productivity, interaction needs, job qualification and creativity. Chapter 7 concentrates on the command and control structure of the economy as seen through the spatial relations entertained by headquarters and their subsidiaries, by Swiss and foreign multinationals, by the public and private sector. Finally, chapters 8 and 9 undertake the inferential part of our work, and aim at testing our core hypothesis of a statistically demonstrable link between accessibility, which is defined and thoroughly studied in its historical dimension in chapter 8, and a measure of job quality. Chapter 9, the last of the work, takes this core hypothesis to the statistical test. The results of this work are multiple. First of all, it shows that the spatial structure of the economy indeed transitioned from a very strong center-periphery organization in 1939, when two thirds of all non-agricultural jobs were located in urban centers, about a quarter in the country-side and the rest in numerous small industrial villages, to a vastly different structure in 2008 with less than half such jobs located in urban centers while suburban centers capitalize about a quarter of them, the rest being distributed mainly in edgeless space – industrial villages having somewhat lost in importance. This work shows that the spatial components of the economical structure have also greatly evolved. While in 1939 urban centers concentrated most of the economic functions and all of the commanding ones, spatial specialization has been relentless since then, and especially since the last quarter of the 20th century. Suburban centers have grown, but also gained in quality, especially in the high tech and the professional services sectors, and in commanding functions: as of 2008, they hosted more jobs in headquarters than in subsidiaries. In parallel, cities have tended to specialize on some key sectors of the economy: finance and governmental services at large, accompanied by personal services catering for the new urban elite. Taken altogether those developments pick at the prevailing spatial economic theories and show a major departure from the Christallerian model. Anecdotal evidence shows that by and large suburban centers seem not located haphazardly in the larger suburban belt, but are concentrated on several specific point within it, namely the higher accessibility areas, especially highway junctions and interchanges. This hints at the possibility that high accessibility is a determinant of job localization. In the course of this work we demonstrated first that accessibility is more dependent on road network changes that to other parameters such as population distribution, technological changes and attitude changes towards commuting, and that the accessibility changes due to road network evolutions display far stronger local accessibility gradients. Secondly, we demonstrated the existence of a link between accessibility and job density taken as a measure of job quality, after taking into account the effects of spatial autocorrelation. Much of the unexplained variance shown by a global regression model can be modeled away as regional effects when using a geographically weighted regression, so that the combination of regional effects and accessibility accounts for a major part of the job density variance. Finally, the introduction of time lags between accessibility conditions and job densities hinted at the possibility that a causal link exists between the two, accessibility changes preceding, and maybe then causing, job density changes: in short, this work shows that accessibility by car is a major determinant of job localization.
EPFL2011
