POST EVALUATION OF ROAD INVESTMENT PROJECTS: HOW CORRECT ARE THE ESTIMATED FUTURE BENEFITS IN THE CASE OF NORWAY?

摘要

The Norwegian Public Roads Administration (NPRA) carries out cost benefit analysis (CBA) for its trunk road schemes. The purpose of this is to provide decision makers with information regarding the economic viability of the projects. Essentially, CBAs are performed ex ante. They are a prediction of what will occur if projects are implemented.A question raised by the government auditors and the decision makers is whether the predicted impacts are actually achieved. Thus in 2005, the Norwegian Ministry of Transport and Communications authorised the NPRA to continually carry out ex post studies of implemented projects to reveal the extent to which predictions are correct. The purpose is to determine how far the NPRA is achieving its objectives and benefits from its road programme. Five major road projects will annually be subjected to ex post studies.By recalculating CBAs of 5 Norwegian road schemes 5 years after the opening with actual data, we find the net present values are greater than forecasted for all 5 projects. One of the main reasons for this is a higher traffic growth rate than forecasted. Investment costs are both under and over estimated. Divergences are also explained by changes in the project design from the before to the after analysis.