Modeling the co-evolution of cities and networks

The idea of possible causal relationships between territorial characteristics and transportation networks has fed a scientific debate that is still active. The underlying assumptions can be synthesized as more or less deterministic attributions of impacts of transportation infrastructures or of a new transportation mode on territorial transformations. Precursors of this reasoning can be tracked back to the 1920s: Burgess et al. (1925 p. 69) mention for example some ‘modifications of forms of transportation and communication as determining factors of growth and decline cycles (of territories)’ (p. 69). Methodologies to identify what is then termed structuring effects of transportation networks have been developed for planning in the 1970s. Bonnafous and Plassard (1974) situate the concept of structuring effects in the perspective of using the transportation offer as a planning tool (the alternatives are the development of an offer to answer to a congestion of the network, and the simultaneous development of associated offer and planning). They identify from an empirical viewpoint direct effects of a novel offer on the behavior of agents, on transportation flows and possible inflexions on socio-economic trajectories of concerned territories. Bonnafous et al. (1974) develop a method to identify these effects through the modification of the class of cities in a typology established a posteriori. More recently, Bonnafous (2017) recalls that the institution of permanent observatories for territories makes these analyses more robust, allowing a continuous monitoring of the territories that are the most concerned by the extent of a new infrastructure. According to Offner (1993) who reformulates ideas already given by Plassard (1977) for example, a non-reasoned and out-of-context use of these methods has then been developed by planners and politicians who generally used them to justify transportation projects in a technocratic manner; through the argument of a direct effect of a new infrastructure on local development (for example, economic), politicians are able to ask for subsidies and to legitimate their action in front of the people. Offner (1993) insists on the necessity of a critical positioning on these issues, recalling that there exists no scientific demonstration of an effect that would be systematic. A special issue of the journal L’Espace Géographique (Offner et al. 2014) on that debate recalled that ‘on the one hand’ misconceptions and misuses were still greatly present in operational and planning communities, which can be explained ‘for example’ by the need to justify public actions, and, on the other hand, that a scientific understanding of relationship between networks and territories is still under construction.