Quantifying community severance - A literature review

Comparing with other local effects of transport planning, the issue of community severance (or "barrier effect") has been neglected by both policy-makers and researchers. Severance is usually defined as the separation of local communities by transport infrastructure or road traffic. In most countries, the issue is either not included in project appraisal or included using general qualitative scales. A diversity of methods for quantifying community severance has been proposed over the years, but these proposals have very rarely been implemented. This paper reviews the existing research on this topic, including government guidance documents for transport appraisal in several countries, reports to public authorities and academic and technical papers. The focus is on the methods to identify and measure the effects of transport infrastructure and road traffic on local mobility and accessibility, especially in the case of pedestrians. The challenges for the integration of these methods in actual transport planning are also identified.