Recent literature on urban planning approaches emphasizes citizen health and with good reason: it was the unhealthy city conditions that frequently decimated city populations in previous centuries that gave birth to the planning profession in the late 1800s; health became its cause célèbre.
In time, one by one, causes or vectors of ill health or death have been identified and city life emerged healthier, often surpassing living in the country, which city dwellers always considered ideal.
Traffic crashes, the subject of this article, are one cause of ill health, impaired living or curtailed lifespan. Here we would like to examine the often cited factor of urban form, and its effect on crashes, or, more specifically, to determine whether city growth, in its sprawl-type outward expansion, has increased the incidence of fatal and injurious crashes. This factor is a relatively recent addition to numerous attempts to pin a correlation or causality linking traffic accidents and any number of causes.
Crashes, fatal and injurious, currently constitute a large social burden. In Australia, for example, calculations show that the total social costs of crashes was 17.85 billion or 1.7% of the GDP in 2006(1).
Graph 1. Source: Tim Risbey et al, The Social Costs of Road Crashes ATRF 2010 proceedings. (Chart by author)