The Wider Costs of Roads on Health and Wellbeing

Abstract

BACKGROUND: The economic valuation of the negative impacts of large roads is often limited to environmental aspects such as noise and air pollution. At the same time, there is growing evidence on the benefits of policies to promote walking, but seldom in the context of policies to reduce the impacts of road traffic. Methods to value other aspects, such as the impacts on health, wellbeing and social cohesion remain scarce. The objective of this presentation is to provide estimates of the overall economic value of these wider impacts of large roads and motorised traffic on local communities. The study is part of the Street Mobility and Network Accessibility project at University College London, which is developing tools to understand physical and psychological barriers to walking in residential areas. METHODS: Data was collected about the impacts of two large roads in London, using a variety of methods. This data was then combined with the unit monetary values available from the literature: a) Traffic levels and speeds and pedestrian crossing delays were obtained by a video survey and combined with unit values for the health effects of air pollution and noise and for the walking time of trips to public transport nodes. b) The quality of the pedestrian environment was assessed using street audits. The resulting scores were combined with values from stated preference and hedonic studies of housing markets. c) A household survey provided information about averted walking trips and social contacts due to road traffic. This data was combined with values for the effects on health, social exclusion, and social capital. RESULTS: The estimated values for the overall cost of the road are high, compared with those usually reported in transport appraisal studies. However, there is a high degree of variability in the estimated values, depending on the sources of the unit values of each impact. The analysis also revealed substantial differences between the values obtained in each study area, which are explained by differences in the characteristics of population and land use. CONCLUSIONS: The accounting of the wider health and wellbeing costs of the presence of large roads in residential areas provides useful information for the appraisal of transport projects, which is often skewed towards the benefits from time savings. However, the use of pre-determined unit values can yield unreliable results for the cost estimates, as these depend on local variables.