Disentangling barrier effects of transport infrastructure: synthesising research for the practice of impact assessment

Abstract

Transport infrastructure such as railways, motorways and arterial roads increases regional accessibility for motorised transport but simultaneously can create barriers in local street networks that can decrease accessibility for pedestrians and cyclists. Although several tools for an objective assessment of these barrier effects have been developed, their use in practice is limited; impact assessments are instead based on subjective descriptions. This article reviews the literature on barrier effects of the last 60 years and aims to offer guidance for the use of objective methods of assessment of barrier effects. The first contribution is a conceptual model for the barrier effects of transport infrastructure and their determinants. The second contribution is an overview of tools for the assessment of barrier effects. We conclude that a multi-disciplinary approach is required, supported by the conceptual model and the overview of assessment tools. Investments in transport infrastructure can then be based on broader decision support involving not only the benefits of increasing regional accessibility but also the cost of reducing local accessibility.