This paper analyzes the feasibility of Bolu Mountain Tunnel vifhich is one of the most costly highway projerts in Turkey. The project continued for
about seventeen years and opened to use m 2007. Internal Rate of Return concept is used as a decision rule to asses the net benefit stream of the.
project. As the tunnel construction had not finished at the deadline planned by the earliest project appraisal, the necessity of tunnel construction
became controversial among the society as it requires high investment costs which are withdrawn from other resources of the economy. The analysis '
is conducted for a 50 year period. According to the.results, Bolu Mountain Tunnel project is not economically feasible since the Net Present Value of
the projea is highly negative at % 12 discount rate level. The NPV and IRR figures are recalculated under different scenarios but even in the best case •
the figures are negative