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Traffic Risk in PPPs, Part II: Bias in traffic forecasts—dealing with the darker side of PPPs

Matt Bull's picture


Photo: Susanne Nilsson| Flickr Creative Commons

This is the second of a three-part series on traffic PPPs.

"It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so."
“The Big Short” 
 
Forecasting traffic accurately is a very difficult and thankless task, as I explained in my previous blog: Traffic Risk in Highway PPPs, Part I: Traffic Forecasting. As such, this gives rise to very real financial risks if these forecasts turn out to be wrong. This risk has crystallized many times as manifested in high-profile distressed projects, bankruptcies, renegotiations and bailouts.

So what’s driving the inaccuracy and resulting risk in traffic forecasts? In the Public-Private Infrastructure Advisory Facility (PPIAF) and Global Infrastructure Facility (GIF) publication, Toll Road PPPs: Identifying, Mitigating and Managing Traffic Riskwe postulate that forecasting inaccuracy comes from three sources:

Traffic Risk in Highway PPPs, Part I: Traffic Forecasting — It’s ok to be wrong, just try to be less wrong

Matt Bull's picture


Photo: Jorge Franganillo | Flickr Creative Commons

This is the first of a three-part series on traffic risk in PPPs

"Prediction is very difficult, especially about the future."
– Professor Nils Bohr, Nobel Laureate

Professor Bohr was right: prediction is hard work. As a species, we don’t have difficulty making predictions. I, for one, frequently make doom-laden predictions on a diverse range of subjects ranging from politics to the fortunes of my beloved football team, Liverpool Football Club.

No, the problem is that humans, as a rule, are not very good at predictions. Sadly, that illusive ‘crystal ball’ still has not been invented. And the sheer complexity of living on an ever-changing and evolving planet alongside 7 billion equally complex individuals—all making unique but increasingly interdependent decisions—makes even the most straightforward predictions difficult.