In this paper four groups of valuation methods are examined. Two of them are based on prices (market or shadow prices and alternative costs as substitute of shadow prices) and two groups are based on willingness-to-pay (revealed preferences and stated preferences). If all data are available, the point of intersection of the demand curve (marginal willingness-to-pay for different amounts of a commodity) and the "social supply curve" (marginal social costs of supply for different amounts of this commodity), hence also a price, can be found. Even then two different bases of valuation exist: either the area under the demand curve, i.e. willingness-to-pay, or, in analogy to earnings at the market, the product of price and amount. Standard values for the costs of fuel, travel time, accidents, pollution and noise are defined according to both bases of valuation. Other operating costs and investment costs are valued by their market prices. The standard values found are applied to the evaluation of an investment project (a motorway project), a regulation (the general speed limit on motorways) and a price measure (level of fuel taxes). To improve the comparability of measures, the results are presented in a standardised framework including transport volumes and conditions, particular effects in physical units, these effects in monetary units and essential decision criteria. The results show considerable differences between both bases of valuation. Valuation based on willingness-to-pay gives higher optimal road standards and higher optimal fuel taxes than valuation based on shadow prices, while the optimal speed limit is similar in both cases. It is therefore recommended to distinguish two types of CBA: (1) CBA based on valuation by total willingness-to-pay; and (2) CBA based on valuation by shadow prices excluding consumers surplus. The former complies with the concepts of welfare economics, whereas the latter avoids distortions between goods provided on markets and those provided by government.
Samenvatting