What is community severance?

Post by Dr Jennifer Mindell

Community severance happens when a railway line or major road splits a community, so people cannot get to the goods, services, or people they want to.  It can also happen where the speed and/or volume of traffic stop people being able to cross the road easily.  This is probably more common. It can make it difficult to get to workplaces or to schools and colleges. It reduces the number of people that local residents meet in their everyday lives.

These social networks, of friends and family but also of acquaintances and neighbours, are important for health.  Appleyard and Lintell in San Francisco in the 1970s showed that the number of friends and acquaintances local residents had was lower the higher the amount of traffic on their street.1  This is explained very well in this video:

More recently, Joshua Hart showed the same in Bristol.

People with fewer social contacts are more likely to have poor health, to be admitted to hospital, and to die younger. Obviously, people who are ill may be less able to go out and therefore see other people.  But this effect on health is found even if you allow for age (because older people are at higher risk of poor health and also may go out less) and consider only people who are healthy at the start of the study.  In fact, the effect on health is of a similar size to the effect of stopping smoking, which is one of the most effective things to improve health.

In our Street Mobility project, we will be developing tools to measure community severance.  Until we can measure it, it is very difficult to say how widespread a problem it is; what makes it better or worse; what the effects of a local road ‘improvement’ will be; and how community severance affects health.2


   1.   Appleyard D, Lintell M. The environmental quality of city streets: The residents’ viewpoint. American Institute of Planners Journal 1972; 38: 84-101.

   2.   Mindell JS, Karlsen S. A review of the evidence on community severance and its impacts on health. J Urban Health 2012; 89: 232-46.


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