What kind of severance to measure?

Post by Dr Jennifer Mindell

One of our first tricky decisions is what level of severance to study in this first project.  Should we study the obvious, major severance that can be seen easily where a railway line or a busy A road or motorway cuts through an urban or suburban area? This may be so bad that people don’t even try to get across; are resigned to the noise and the dirt from the road; and live their lives on ‘their’ side of the obstruction. It affects their quality of life and maybe their mental wellbeing and even their physical and mental health, but could anything realistically be done to change it?  Are options, such as diversions for pedestrians, underpasses, or bridges no better than not crossing the roads?

Should we look at the more subtle effects on residential streets (what Appleyard calls ‘neighbourhood streets’), where people might expect to live in relative peace, with easy access to their neighbours across the road as well as next door, and where the streets used to be used as social spaces until rat runs and general increases in traffic levels discouraged them?  Appleyard and Lintell also found that people on heavily trafficked streets reporting their ‘home territory’ as only their own home, or even just the rear part of their home.  In lightly trafficked streets, residents often described their whole streets as their ‘home territory’.

There are effects of community severance for people of all ages.  For example, playing and traveling independently outside improves children’s physical and psychological development.  However, because we cannot do everything at once, we are focussing on people aged 50 and above for this first study.  Once we have chosen our case study areas, we will be asking groups of local residents what they think the important issues are, to ensure we develop a tool that measures what they think matters.


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.