The paper presents the findings of a study undertaken by Rendel planning and the Environmental Appraisal Group and the University of East Anglia on behalf of the Transport and Road Research Laboratory (TRRL), which was completed early in 1990. A brief consideration is given to the role of the Manual of Environmental Appraisal currently used by the Department of Transport, (see IRRD 272761) the measures used in assessing environmental impact and its contribution to the process of selecting the preferred route for a new road proposal. The paper poses the principal problem of evaluating alternative schemes which have varied environmental impacts and different net present values following cost-benefit analysis. A review is presented of methods by which money values can be ascribed to environmental effects- particularly hedonic pricing, travel-cost approaches and contingent valuation: Theoretical problems with the different methods will be briefly considered. The paper then considers the practical issues of applying these techniques to the environmental effects of road schemes with examples drawn from recent road proposals in the Midlands. The first part of the paper discusses practice overseas where attempts have been made to provide an overall evaluation of varied environmental, economic and transport effects of alternative proposals.
Abstract