A study by Oxford University professor Bent Flyvbjerg of 258 rail, bridge and road “megaprojects” revealed that many go vastly over budget and perform poorly when completed.

“… it is becoming clear that many such projects have strikingly poor performance records in terms of economy, environment and public support. Cost overruns and lower-than-predicted revenues frequently place project viability at risk and redefine projects that were initially promoted as effective vehicles to economic growth as possible obstacles to such growth.”

“The Channel tunnel, opened in 1994 at a construction cost of £ 4.7 billion, is a case in point with several near-bankruptcies caused by construction cost overruns of 80 percent, financing costs that are 140 percent higher than those forecast and revenues less than half of those projected”

“Moreover, positive regional development effects, typically much touted by project promoters to gain political acceptance for their projects, repeatedly turn out to be non-measurable, insignificant or even negative”

Source: Megaprojects and Risk: An anatomy of Ambition, by Bent Flyvbjerg, Nils Bruzelius, and Werner Rothengatter