Contenu du sommaire

Toward a territorial theory of networks : an application in the field of urban transit. More than thirty years ago, in an homage to Lucien Febvre, M.-F. Rouge wished the coming of a theory of networks, considered as systems of spatial organization. Today, with the help of many individual and group research works, by geographers and other french scholars, appears a territorial theory of networks. These theory lays on the notion of transaction. Transactional projects of actors located in various local points shape their territories and at the same time draws a virtual network. This is actualized by a collective actor, the network operator, who combines the single actors projects, manages technical, juridical, political constraints so as to build and to operate the actual network (for example, an utility network). Difference between this actual network and the virtual one means a more or less good adaptation of the network to the territory. This difference can be evaluated by using specific indicators, related to network organization : connexity, connectivity, homogeneity, isotropy, nodality. Applying this theory, the R.A.T.P. (Régie Autonome des Transports Parisiens) made recently a study concerning a bus network in the Paris region. The study tried to compare three different figures corresponding to different arrangements of the bus lines in the same area. Results acquired by comparing the indicators in the different cases were confirmed by surveying a sample of population of the area (and outside). The survey demonstrates that people had the same preferences about the proposed forms of networks that the theory would have predicted. Those interesting first results should lead to other tests of this territorial theory of networks.

Capital of motor industry, sort of factory-city built by the big firm F.I.A.T., Turin has had a cycle prosperity-crisis-economic reorganizing, since the last twenty years. The solutions to economic recession have been : automatization, employment cuts, new business relations between big firms and smaller firms, and finally new suburban activity centres. Along with this new development, a project for a network « technopole » — Tecnocity — is born. It aims to qualify employment, to create a synergy between venture-capital, research, motor industry, electronics, automation... It's also meant to give a new part to city space and to set this Piemont capital into international business exchanges.

Italy considered as a country of external migration, sends only now a few migrants towards european countries and receives immigrants, principally by illicit ways. In the same time, the direction of internal migration is changing. Now, the central regions are more attractive than northem Italy. An important bibliography of Italian publications follows.

This paper summarizes three topics presented in a book on Los Angeles published at Pion, London, in 1986. A graph showing points moving over time describes the evolution of social segregation : they come doser as the socio-professional groups they represent tend to dwell together in the same tracts. The four censuses taken from 1940 to 1970 leads to the construction of a « data-cube » crossing tracts with variables with years. Three-way factor analysis extracts information from this cube and produces a map summing up the evolution of the city. Auto-correlation of land rent exhibits, through the « variogramme », an oriented spatial structure, a relie from the time of the electric streetcars who shaped the city.

The damages of the earthquake of the 19th and 20th of september 1985 result of tectonic movements, shallow anticlines and sinclines and not of any subsidence associated with the compaction of lacustrine sediments. The historical part of Mexico, where subsidence is intensive as a result of excessive extraction of ground water has not been affected. The folds are characterized by extensive strains on the anticlines, strains which increase with the altitude above ground level. The buildings have been tilted and « opened » from above (photos 4 and 6). Asismic building standards do not contemplate such a strain and have to be revised. It is recommended to study seriously the geomorphic aspects of the seisms, to abandon the construction of skyscraper, above all with glasses instead of walls, and to come back to the more traditional type of buildings, with few floors and consisting of brick and stone walls.