In the February 2010 issue of IP, the Editor’s Choice is “Using geographical information systems to assess the equitable distribution of traffic-calming measures: translational research.”

This paper by Sarah Rodgers and colleagues complements the Advocacy in Action study currently underway by the same group.

In the study, the authors used traffic calming data on almost 100,000 km of road in various areas in the UK. They were able to link these data using GIS analysis to population data, including measures of local deprivation.

Two findings stand out. First, only a small proportion of roadways are traffic calmed (3.7%). Of course, it is not clear what fraction of all roadways are eligible for such. And the data sets used registered only speed humps, whilst traffic islands, chicanes, “road diets,” etc. are all addition forms of traffic calming for speed reduction.

Second, deprived areas had a relatively higher proportion of roads calmed than did more affluent neighborhoods. It is interesting to see (finally) a health intervention that is disproportionately applied to poorer communities. What is not clear is why this happens: is there reduced demand in affluent areas? Do wealthier neighborhoods resist these modifications? Are they less valued in well-off communities where walking is less likely to be a common mode of transport? Or is traffic calming in richer areas already achieved through zoning or street treatments not apparent in the database used?