Transport evaluation, and urban policy in general, invariably requires us to make trade-offs between the present and the future. When we invest in the built environment – roads, rails, buildings, etc – we are expending today’s resources on projects that will primarily benefit people in the future. Conversely, decisions we make about resource use today – e.g. how much greenhouse gas to emit – will impose increasing costs on future generations.
Individuals also make decisions that involve trade-offs between the present and the future. For example, most home-buyers take out a mortgage, which allows them to spread the payments over a long period of time in exchange for paying a bit more in interest charges. For the borrower and for the bank, the interest rate paid on the debt reflects the trade-off between repaying the debt today or repaying next year.
Of course, there are also other ways that individuals make trade-offs between the present and the future. They may, for example, spend money on their children’s education, even though the “returns” from doing so are long-term and indirect. Or they may vote for policies that cost them money now but return long-term benefits, such as environmental protection or pre-funding of superannuation.
The trade-offs that governments make between present and future are codified as discount rates, which describe how much of a “discount” we place on future outcomes relative to present outcomes. For example, a discount rate of 10% means that the government would value a benefit of $100 in a year’s time as being equal to a benefit of $90 today.
Transportblog’s previously taken a look at the discount rate issue here, here, and here. But others are also engaged with the issue. Back in August, University of Michigan economics professor Miles Kimball, who had been visiting the Treasury, strongly criticised its approach to discount rates. The key point in his critique is that the Treasury’s discount rates don’t accurately reflect the financial market returns currently available to the government:
There is an extremely strong argument against using an 8% real discount rate in evaluating government projects. I think the argument below can be sharpened to become institutionally relevant.
Basically, an 8% real discount rate makes no sense to use unless the New Zealand government is actually getting an 8% real return on funds that it saves. It is not enough for someone to claim that the New Zealand government theoretically could get an 8% real return on funds it saves when that is not true or is only theoretical because the New Zealand government would never actually do that with funds saved by not doing a project.
Just to be clear, my view is that (a) all projects that are better than putting the money in the Superfund should be done, and (b) if someone claims that a project is worse than putting money in the Superfund, then money should be put in the Superfund instead, and (c) if a project looks better than paying off some of the debt by buying bonds–or, almost equivalently, good enough that borrowing at the bond rate to do it looks like a positive present value–it should also be undertaken UNLESS the government is willing to issue additional bonds to put more money in the Superfund invested in risky assets.
I’ve skimmed over a lot of the substance of Kimball’s argument, which I encourage you to read. (Warning: it’s wonky.) After Kimball’s blog post, former RBNZ economist Michael Reddell wrote a blog post defending the Treasury’s policy. Reddell’s counter-argument is that financial returns to government is the wrong measure of the time value of money:
I was struck reading Kimball’s material that the cost of the government’s equity did not get a mention. There was a strong tendency to treat the government as an autonomous agent (like a household) managing its own wealth, whose low borrowing costs depends only on the innate qualities of the government and its decision-makers. But that is simply wrong. A government’s financial strength – and ability to borrow at or near a conceptual “risk-free” interest rate – rests on the ability and willingness of the government to raise taxes (or cut spending) as required to meet the debt commitments. That ability to tax is implicit equity, and it has a cost (an opportunity cost) that is considerably higher, in most cases, than 2.5 per cent real. So long as the government will raise taxes as required, the bondholder bears none of the downside if a project goes wrong. But shareholders – citizens – do. Bearing that risk has a cost, and that cost needs to be taken into account by government decision-makers.
There is a related argument sometimes heard that governments should do infrastructure projects rather than private firms simply because the government’s borrowing costs are typically lower than those of a private firm. But, again, that rests on the power to tax, and the ability to force citizens/residents to pay additional taxes has a cost from their perspective (even if the government never chooses to exercise the option). As citizens, the possibility that the government will raise taxes (or cut other spending programmes – eg NZS) impinges on our own ability and willingness to take risks, and hence to consume or invest in other areas. That often won’t be a small cost. The opportunity cost of the government not undertaking a project is not what, say. the NZSF might be able to earn on the funds, but what citizens themselves might prefer to do if that risk-bearing capacity was freed up.
Again, I’ve skimmed over Reddell’s argument, so I’d encourage you to read it in full if you’re interested. He throws in a brief jab at road projects with low BCRs:
We have too little disciplined analysis of the costs and benefits of most government projects, and too little willingness to allow decisions to be guided by the results of the analysis when it is undertaken (did I hear the words “Transmission Gully”?).
I can see some truth in both sides of the debate. Kimball’s got a good point, which is that current government borrowing costs (and financial market returns in general) are at historic lows, which should lead to lower government discount rates. But Reddell’s also correct that it’s appropriate to set discount rates based on wider social decisions about consumption and investment.
One issue that neither of the two grappled with in detail was the question of how risky government investments actually are. Kimball touched on that briefly, arguing – essentially – that the benefits of projects will inevitably rise in the future due to people’s greater willingness to pay for public goods in the future:
A good method of risk adjustment for projects is to think seriously of the real dollar value they will have dependent on the level of real consumption in the economy. One virtue of thinking about the adjustment this way is also that it provides a reminder that the dollar value of the flow of benefits from many projects will tend to increase in the future simply because trend increases in per capita income will raise the willingness to pay for those benefits.
Frankly, I don’t think this is correct. Changes in technology, changes in prices, and changes in preferences mean that infrastructure that’s useful today can easily become a stranded asset tomorrow. Look at Los Angeles: in the 1950s it was rushing to rip up its rail lines, and now it’s rushing to build a new rapid transit network. Or look at San Francisco: several of the elevated expressways it built in the 1960s have been torn down.
In short, things change. Sometimes they change quite radically. When the Ministry of Transport looked at future transport demand last year, they found that they couldn’t settle on a single forecast for future transport demand. Instead, they arrived at four scenarios, three of which entailed a decline in vehicle travel:
In other words, there can be considerable uncertainty in returns from transport investments. While it might not necessarily be appropriate to try to account for this in discount rates, it’s surely an important consideration for project evaluation more generally.
What do you think about discount rates?