With most business opportunities, it is possible to calculate the expected monetary benefits and costs, while considering other factors such as the opportunity cost of capital and project risk.A similar approach for transport infrastructure projects is also attractive. Just work out the benefits in today’s money, divide this by the cost and – presto! – you know exactly how much the economy will benefit from for every dollar spent.
Take the proposed Waterview motorway extension, for example. Treasury and Ministry of Transport officials have worked out that for every dollar spent on the $2.8bn motorway connection between Mt Roskill and Waterview, the economy will receive $1.15 worth of benefits.
In the business case document now being considered by Cabinet, officials point out that “full tunnel” option means that the benefits are only a little in excess of their costs. Some above ground options might save up to $200m from the construction cost, but these have higher social and environmental costs, and also involve the loss of park land and a significant number of houses.
Considering the billions of dollars at stake, one would hope that the economic benefits and costs of the various options are as accurate and as realistic as possible. So are they? Well, no, actually.
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