These studies have partly been in the form of attempts at monetary valuation, using the "Contingent Valuation Method" CVM, which roughly speaking means, hypothetical market valuation, and partly in the form of "for or against" studies. The former method is particularly suitable when winners and losers are distinctly separate groups, and the latter is appropriate when the groups overlap to a great extent, which is usually the case when the investment concerns a local road. The results of completed studies indicate that encroachment costs, in certain cases, can be of such a magnitude, that a project, that in terms of the Cost Benefit Analysis should have been an extremely profitable one, in reality becomes social-economically unviable. Therefore, the conclusion to be drawn must be that today's road impact assessments need supplementing. Despite the problems that exist with the CV method and "for or against" studies, they may be the supplement required.
Abstract