Proceedings of the conference Forum Vies Mobiles: What ideal model for the city of tomorrow?

Dense city or peri-urban? That is to say, downtown, where the transport network is very developed and reduced travel, or city located on the outskirts, where distances take all their importance and the car is compulsory?

The dense city is often set up as a model in particular because it would limit our travel, our CO2 emissions and it would promote social ties. At the same time, barbecue effect theorists * have shown that by taking into account the kilometers traveled for leisure mobility, which is constantly increasing, people living outside cities have total mobility comparable to that of inhabitants of central cities.

Today, is there really a more virtuous city model than another?

Contrasting points of view were presented during the FVM conference and provided some answers to these questions:

Presentation by Jean-Pierre Orfeuil

Mining engineer and doctor of statistics, professor of planning at the Paris School of Urban Planning (EUP), Paris-Est Créteil Val-de-Marne University.

Jean-Pierre Orfueil presented the evolution of research on the link between density and mobility. The paradigm of the dense "virtuous" city appeared with the work of the Australians Newman and Kenworthy in the 90s. The latter presented a simple link between greater density of agglomerations and lower energy consumption of the inhabitants for their daily trips. To do this, they compared behavior in 37 cities in North America, Australia, Europe and Asia. This research had a very strong impact on the imagination of urban planners and on the policies carried out in favor of the dense city.

Jean-Pierre Orfeuil has shown, through his work on long distance mobility (leisure or work), that one travels about the same number of kilometers in the dense city as in its peri-urban. There is thus a compensatory effect in this latter living environment where long distance mobility is less numerous, in particular for leisure travel. This has been called the “barbecue effect *”, considering that the “greener” living environment encouraged people to stay more at home for leisure and vacations.

Presentation by Vincent Kaufmann based on Sébastien Munafo's thesis

Scientific director of the Forum Vies Mobiles and director of the Urban Sociology Laboratory (LaSUR) at the École Polytechnique Fédérale de Lausanne

The objective of the thesis, funded by the Forum Vies Mobiles, by Sébastien Munafo, geographer, was to identify the impact of the urban environments of Geneva and Zurich (central, suburban and peri-urban city) on occasional long-distance travel and especially leisure mobility.

His analyzes gave rise to a certain number of results:

• By studying all types of mobility (all reasons combined), the author notes a decreasing link between the density of the living environment and the kilometers traveled on a daily basis, and a positive correlation between this density and the kilometers traveled during occasional trips. The denser the living environment, the greater the occasional mobility.
• Despite this, travel by central urban residents remains less emitting CO2 than that of peri-urban residents. This is mainly due to the lower use of the car by residents of city centers compared to residents of the periphery.
• Finally, living in the city center seems to be correlated with more daily leisure activities in the city and to reside in the periphery with leisure activities closer to nature.

In conclusion: Dense city or periphery? A unique ideal model does not exist.

Christophe Gay, co-director of the Forum Vies Mobiles:

“It emerges from this conference that trying to resolve the issue of CO2 emissions linked to our mobility by favoring the dense city is a mistake. On the one hand, because there are aspirations for diverse urban or rural lifestyles. On the other hand, because the results show that we must first of all take an interest in the different lifestyles that unfold within these living environments. In particular, the level of income is a much more determining factor than the latter in explaining the adoption of more or less CO2-emitting mobility. The richest emit significantly more CO2 than the more modest. "

* Barbecue effect: compensation for a living environment that is too dense or too intense.

To find the conference on video, go to: http://fr.forumviesmobiles.org/meeting/2017/02/13/mobilite-vertueuse-atouts-ville-dense-remis-en-cause-3481