From Deh Cho BridgeWiki
It would be interesting to try and update the old Cost Benefit Analysis (CBA) for the Bridge to reflect the new situation, with higher construction costs, different numbers for ferry savings and bridge O&M, etc.
- The original $165 million construction cost was spread out over 3 construction seasons, at 30%/50%/20%. They applied a 5% annual discount rate, and produced a $155 million NPV cost. But (aside from the overruns), the bridge is not being financed from GNWT revenues, but instead from the $165 million borrowed via the bond issue, which is being repaid back over 35 years. My question is, should the NPV for the construction cost actually have been calculated by discounting the 35 year stream of bond repayments? Or is there some good reason to discount this amount over the construction period, even though that isn't how the actual financing is being done?
Discounting over the 35 years would seem to make the project come out more favourably. Even though with interest the total cost of the borrowed $165.4 million is actually the current equivalent of about $297 million, discounting that at 5% over 35 years of payments would seem to be in the NPV ballpark of $136 million instead of $155 million?