Critical assumptions in Cost-Benefit Analyses (CB A): Norwegian experiences

During the last years there has been an emerging need for a better tool for Cost/Benefit Analyses (CBA) considering heavy infrastructure investments in Norway. Some experiences from certain private financed strait crossing have shown that the conventional tools for CBA may be unappropriate. Huge infrastructure investments are under planning or implementation both in Norway and tnroughout Europe (EuroTunnel, The Great Belt link, Stretto de Mezzina). The main part of this paper will be to discuss some of the assumptions in CBA which must be carefully examined to avoid erroneous investments. There are reasons to say that the most important element of uncertainty in CBA is the future traffic volumes.