Our main research focus in cost-benefit analyses (CBA) lies in the appraisal of major projects. The CBA constitutes an instrument which provides support for public decision makers on the assessment of public measures. In accordance to specific macroeconomic objectives benefits comprise effects which are jugded positively. Respectively costs cover all negative effects. Increasing the public welfare makes up a general goal. The specific economic approach in project assessment is characterised by applying the with-or-without principle and by taking into account opportunity costs. Anyway, using CBA may result in a substantial efficiency of public means.