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Wednesday, November 24, 2021
Infrastructure Projects: History of Understated Costs and Overstated Benefits
"It sometimes seems as if every big infrastructure project
underestimates its costs and overpromises its benefits. But is that a
few bad apples that get a lot of publicity, or is it the real overall
pattern? Bent Flyvbjerg and Dirk W. Bester put together some evidence
in “The Cost-Benefit Fallacy: Why Cost-Benefit Analysis Is Broken and How to Fix It” (Journal of Benefit-Cost Analysis, published online October 11, 2021).
They collect “a sample of 2062 public investment projects with data on cost and benefit overrun. The sample includes eight investment types: Bridges, buildings, bus rapid transit (BRT), dams, power plants, rail, roads, and tunnels. Geographically, the sample incorporates investments in 104 countries on six continents, covering both developed and developing nations, with the majority of data from the United States and
Europe. Historically, the data cover almost a century, from 1927 to
2013.” Not all of these studies have data on both expected and realized
benefits and costs. But here’s a table summarizing the results: On
average, there are cost overruns in every category, and overstated
benefits in every category. In more detailed results, they show that
this pattern hasn’t evolved much over time.
Of course, the average doesn’t apply to every project. Indeed,
sometimes there are cost overruns but then even bigger benefits than
expected. But the average pattern is disheartening. Indeed,
“[c]onsidering cost and benefit overrun together, we see that the
detected biases work in such a manner that cost overruns are not
compensated by benefit overruns, but quite the opposite, on average. We
also see that investment types with large average cost overruns tend to have large average benefit shortfalls.”
The essential problem here, Flyvbjerg and Bester argue, is that those
who do these estimates of benefits and costs are overly optimistic.
The root cause of cost overrun,
according to behavioral science, is the well-documented fact that
planners and managers keep underestimating the importance of schedules,
geology, market prices, scope changes, and complexity in investment
after investment. From the point of view of behavioral science, the
mechanisms of scope changes, complex interfaces, archeology, geology,
bad weather, business cycles, and so forth are not unknown to public
investment planners, just as it is not unknown to planners that such
mechanisms may be mitigated. However, planners often underestimate these
mechanisms and overestimate the effectiveness of mitigation measures,
due to well-known behavioral phenomena like overconfidence bias, the
planning fallacy, and strategic misrepresentation.
Thus, the question is how to get those estimating the benefits and
costs of mega-projects to be more realistic. The authors offer some
suggestions.
“Reference class forecasting” is the idea of basing your estimates on
look at actual costs and benefits that happened with similar projects
in other places, representing a range of better and worse outcomes.
Another idea is to give the benefit-cost forecasters some “skin in the game.” “Lawmakers and policymakers should develop institutional setups that reward forecasters
who get their estimates right and punish those who do not.” This can be
done in friendly ways, with bonuses, or it can be done in punitive
ways, with lawsuits and even crimial punishments when things go badly
wrong. There can be a rule in advance that independent audits will be
carried out during and after the project–perhaps even by several
different auditors. Finally, the decisions about whether to proceed
shouldn’t just involve technocrats and spreadsheets, but also need
public involvement. For example, if the public is going demand processes
that slow down or complicate a project, that needs to be taken into
account at the start–even if those demands may seem irrelevant or
counterproductive to the forecasters.
The authors note that these kinds of changes are being used in
various places and by various governments around the world. If there are
plans for a megaproject where you live, you might want to think about
whether these processes might lead to more accurate benefit-cost
estimates, too."
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