Appraising the Environmental Effects of Road Schemes. A Response to the SACTRA Committee

In this paper, we consider the range of environmental effects of roads and ways of valuing them in money terms. We conclude that environmental effects should be divided into strategic and local. The former, which are largely ignored by current appraisal practice, should be considered as part of an appraisal of the entire programme of road schemes in the course of the consideration of transport strategy. Local effects are dealt with in the Manual of Environmental Appraisal, but the list of effects there and advice on their treatment needs amplification.

We consider that techniques for the monetary valuation of environmental effects have improved greatly in recent years, and there remains considerable unexploited potential for the use of stated preference techniques. Nevertheless, we do not think it sensible to suppose that all environmental effects could or should be incorporated in a single Net Present Value calculation; rather we see a potential for the further application of decision support systems able to deal with more disaggregate information.