The diffuse city

Eric Charmes, October 2015

In Italy, the concept of the « diffuse city » became part of the debates following the publication in 1990 of a book entitled La Città Diffusa, directed by Francesco Indovina. This concept was then disseminated in France, notably through Bernardo Secchi (2002). The latter played an important role in the exchanges between French and Italian urban planners on the issues raised by peri-urbanization. For Bernardo Secchi, «  diffuse, dispersed city will be the icon of the 21st century ( la ville diffuse, dispersée, sera l’icône du XXIe siècle) ". Here is how he recently defined this concept: «  The typical example is the region around Brussels, in the broad sense. This vast urban area is highly dispersed and includes several important cities such as Amsterdam, Antwerp and The Hague. Another example is the Italian Veneto region, a sort of vast inhabited area without a dominant center. The diffuse city goes hand in hand with a way of life, that of the single-family house with a small garden. I think this is a cultural trait of the 21st century. This « ideology » has become very strong in Europe. I see it when people tell me, as a matter of course, that they are going to get married, have children and therefore move to the country.

The diffuse city is therefore primarily made up of individual houses. While this characterization is obviously important, it does not explain the originality or specificity of the concept. A second constituent element of the diffuse city is the strong presence of the countryside. Unlike urban extensions in the form of suburbs, where the countryside gradually disappears as the city expands, the diffuse city extends into the countryside without the latter disappearing. In the diffuse city, the countryside and urbanization intermingle, constituting what Bernardo Secchi has called a « leopard’s skin.

The third element of the diffuse city is the absence of a dominant center. Unlike the concept of the peri-urban, which emphasizes dependence on a center, with the concept of the diffuse city, this dependence is considered secondary, insofar as it is not only housing that is diffused into the countryside, but also businesses, services, facilities, etc. Thus, the diffuse city is a countryside dotted with polarities of varying importance, with no clear hierarchy between them, as if the territory were isotropic.

Finally, and this is the last characteristic of the diffuse city, it is formed without any intervention by planners. The diffuse city is the result of the addition of individual initiatives, such as the families mentioned by Bernardo Secchi who, one after the other, decide to settle in the countryside and often also to create a business there.

Like many other concepts, the concept of the diffuse city was born from the observation of a new reality. Bernardo Secchi spent most of his career in Venice and developed his thinking by observing the Veneto. Unquestionably, this territory has particular characteristics that the concept of diffuse city allows to express particularly well. If, in the above quotation, Bernardo Secchi also highlights the case of Brussels, it is because the Brussels region has been the subject of an in-depth investigation by Bénédicte Grosjean (2010) where it is shown that the concept of diffuse city allows to account for the particularities of urbanization in the Belgian Brabant (Grosjean, 2010).

This case also shows the extent to which it would be simplistic to associate the diffuse city and automobile mobility too closely. In Belgian Brabant, the diffuse city came into being with a rail service. The railway network formed an extremely fine mesh, with the development at the end of the 19th century and the beginning of the 20th century of a network of byways directly linking many rural towns and small cities. On this basis, housing and also jobs were spread over a vast territory. From this point of view, works on the diffuse city have a historical depth that those on the emerging city or on the zwischenstadt do not have.

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