The urban spreading out is an expression indicating the phenomenon of development of urbanized surfaces in periphery of the big cities. This spreading out, which is related to the demographic development of the Agglomération S, is done with a density of the all the more weak frame as one moves away from the heart of the cities. The weak density is due to the suburban character of this urbanization, the surface occupied by a hearth (Maison + privative Jardin) being more important than that of a Appartement in Immeuble, like with the importance of the natural spaces preserved in the communes concerned.

History

Already at the 19th century, the theories hygienists recommend, at one time when City industrializes (with all the consequences that involves), one weak density in order to “make circulate the air”. This movement is accompanied by the first forms of public transport, which increase the Mobilité populations: the Railroad. It is as to mitigate the disadvantages of the city as Ebenezer Howard (English town planner) imagines the concept of the garden cities, involving an urbanization with weak density.

The development of the Automobile and its democratization allow a strong increase in urban spreading out, because displacements were freed from the dependence related to public transport and thus allowed the multiplication of these urbanizations of very weak density, primarily served by the highway network. The increase in urban spreading out is of this fact chronologically related to this democratization of the car. It develops massively as of the middle of the 20th century with the the United States and in the last quarter of the 20th century in Western Europe.

The concept

The main motivation of the people choosing this mode of habitat is to escape the high cost, sometimes prohibitory, of urban housing, because primarily of the strong demand for the central districts. To choose the zones périurbaines often allows, for the price of a Appartement downtown, the purchase of a vaster Maison with garden. The principal disadvantage is the distance of the work place (the Télétravail not having allowed yet to replace significantly and effectively physical concentration of the individuals in buildings in order to produce a collective economic activity) which causes the pendular migrations and the congestions, without counting the ecological impact of such a development. Moreover, the benefit induced by the weaker cost of housing is reduced by the costs pulled by the distance. 2 cars per hearth are almost essential in the suburban zones, they represent in the long run a very significant part of the family budget.

Another important motivation is the choice of a more pleasant Cadre of life because nearer to the Campagne, calmer, and which makes it possible to escape the “urban accumulation”, which would cause aggressiveness and Stress. The city suffered from its negative image and still suffers from it, in spite of the clear improvements of the framework of life downtown.

Urban spreading out can be put in parallel with the development of the car fleet and the road infrastructures, of zones of marketing activities and industrial, which require important surfaces and which are rejected downtown areas at the same time because of the cost of the real estate and because of the rejection of certain harmful effects related to these activities.

Is it in fact of a concept or rather about a report related to several phenomena, as well individual as collective? There were not rationalization, but rather natural tendency, that the speeches on the control did not stop:

  • with in an individual capacity, will to profit from the services of the big city without supporting the constraints, the difficulty in of them choosing a housing close to its work whereas one works to two or more and that professional mobilities make null and void the first choice quickly, according to the age of the children, the wish to offer to them spaces of calm and greenery;
  • on a purely collective basis, the attraction of the metropolises and thus the needs for expansion, the wish of the communes of the periphery to also profit from the contribution of population which allows to maintain schools and basic services, finally the clear absence of coherent policy and firm limits to the urban expansion (absence largely related to the real or supposed weak density territory).

Limits and criticisms

An impact on the Rurality

That causes, for the managers of services of general interest, a rise in the expenditure necessary to construction and the maintenance of the networks (water, gas, electricity, phone lines, transport of people, whether they are public transport or roads, etc). This expenditure is not to neglect, because they are not related to the increase in the population, in weak growth in the Western countries: the main part of the new networks are established to serve a population dispersed and not very dense, which in the long term makes problematic the damping of the expenditure, which is higher for the whole of the community. Symmetrically, in the already urbanized territories, under increasing use of public equipment degrades the financial conditions of their current management, their maintenance and expensive settings to the standards.

It involves the constitution of “dormitory towns” and strong pendular migrations, which requires greater investments in road infrastructures, and greater energy expenditure, as well as larger a pollution with the Carbonic gas. Moreover, the increase in artificial surfaces increases the gravity and the speed of the floods.

Beyond these technical sides, urban spreading out can cause a loss of rurality, at the same time like landscape element and lifestyle.

An obstacle with the Sustainable development

According to IFEN, 60.000 hectares of natural or agricultural grounds disappear each year in France under the effect of the urbanization. Artificial surfaces (roads, buildings, carparks, etc) increase three times more quickly than the population (in France, the population increased by 8% of 1982 to 1999, artificial surfaces of 42%). In certain areas, artificial surfaces even doubled during the same period (case of the Pas-de-Calais. While artificialisant more and more of grounds (vaster roads, individual dwellings…), they are unceasingly more agricultural, forest, pastoral spaces or natural spaces which disappear, and with them them fauna and them Flore. In jargon biologist, the disappearing Biotope, the associated Biocénose disappears, and consequently, the ecosystem does not exist any more. In addition to fauna and the flora, the artificialized grounds harm the infiltration of rainwater and support the streaming, factor of erosion on the grounds - cultivated or not - joint. Urban spreading out can thus involve rarefaction - even disappearance - certain animal species (like the tortoise of Hermann or some Grenouille S) or vegetable. The parcelling out of the natural habitat, which can constitute a barrier with the Flux of genes between the various populations of the same species, can thus be at the origin of a reduction of genetic diversity.

Lastly, the energy cost of this type of development is high, because of increase in displacements which it induces and of the greatest difficulty of heating and of isolating thermically constructions from weak density which accompany urban spreading out.

ghettos?

One can also wonder on the phenomenon of segregation of this mode of development and about the absence of social diversity. The private housing estates are indeed built in very few times and are populated by very similar hearths: young couple with children in bottom old or projecting to have some. (few single people, elderly, couples without child)

Evolution of the legislation

In France, the legislator tries today to limit the process of urban spreading out, especially since the law SRU (Solidarity and urban renewal) of December 31st 2000. The main objectives of this law are to limit urban spreading out and, in parallel, of redensifier the centers cities by supporting the Urban renewal in particular.

See too

Internal bonds

External bonds

  • Bibliography on urban spreading out

  • American urban model confronted with the Parisian urban model: two metropolitan approaches comparison of urban spreading out in Paris and the United States
  • the conference organized by Urba+, the network of the Institute of Town planning of Paris, on the topic: " Dense Cities: can the density stop urban spreading out? "
  • Marc Wiel, " Polysemia of the density… how to live with… " , contribution to the conference " Dense Cities: can the density stop urban spreading out? " , organized by association Urba+, PUCA, Ministry for the Equipment, December 20th, 2006

Sources

Random links:Prony | James Napper Tandy | Francis Larivée | Joseph Schmidt | Praia das Palmeiras

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