Activity Spaces, Biographies, Social Networks and their Welfare Gains and Externalities: Some Hypotheses and Empirical Results

Abstract

The repeated interactions and exchanges in formal and informal networks, e.g. family, firms, associations, friendship circles, regulars of a bar, are central to our daily life. There is no reason to assume that the geography of the members of the networks, to which one belongs, has not been affected by the seminal drop in transport and telecommunication costs since 1950. The article will develop a conceptualisation of the dynamics of the interaction between the geographies of the social networks and of activity space growth. Against this background more detailed, testable hypotheses about the change of the geographies, of the contact intensity distributions and numbers of contacts will be derived. The hypotheses will be illustrated with results from a number of surveys, in which first attempts have been undertaken to obtain the necessary data to test the hypotheses. The final section will discuss the impact of the hypotheses, if found to be true, on both transport modelling and transport policy.

Keywords:

• social networks
• travel
• biography
• change
• generalised cost
• anomy

Acknowledgements

This article develops ideas that have been presented and discussed on a number of occasions (Axhausen, 2002, 2005). The author is grateful for the suggestions and critique, which arose at seminars organised by M. Grieco, Cornell University, Martin Lee‐Gosslin, Laval University, Julian Hine, University of Ulster, Fritz Busch, Technische Universität München, Barbara Lenz, DLR, Berlin, Uwe Serkölt, Universität Zürich, and Ph. Toint, FUNDP, Namur. The on‐going discussions with M. Grieco have shaped this article in many ways.

The article has also benefited from the joint project ‘Social networks and future mobilities: “Meetings” in the twenty‐first century’ with J. Urry and J. Larson at the Lancaster University, funded by the Horizons Programme of the UK Department for Transport, and with T. Ohnmacht, TU Berlin on the project ‘Mobility biographies, mobility tools and social networks’, funded by the Institut für Mobilitätsforschung, Berlin.

Notes

1. The enormous attrition rates of the ‘small world’ experiment reported in Dodds et al. (2002) raise the question of whether, and if so how quickly, information will spread in such networks (see Huberman & Adamic, 2005, for a review of this issue).

2. The confidence interval is that part of the real numbers that will include the true, population mean value with a specified confidence, and is calculated using the mean and variance of the sample at hand. For normally distributed values it will also contain 95 per cent of the values of the population.

3. Margaret Grieco suggested this concept during discussions in the course of the UK Department for Transport‐funded project ‘Social networks and future mobilities: “Meetings” in the twenty‐first century’.