Source: adapted from Flyvbjerg, B. (2009) "Survival of the unfittest:
why the worst infrastructure gets built—and what we can do about
it", Oxford Review of Economic Policy, Vol. 25, No. 3, pp. 344-367.
Inaccuracy of Transportation Project Cost Estimates by Type of
A database of 258 transportation infrastructure projects spanning
the world reveals systematic and very high cost overruns; 9 out of
10 projects. They are on average 44.7% for rail, 33.8% for bridges
and tunnels and 20.4% for roads. Standard deviations are also very
significant, particularly for bridges and tunnels, which underlines
the high risk of transport infrastructure projects. Additionally,
there appear to be no significant geographical and temporal
differences in cost overruns.