Numerous state highway programs have suffered cost overruns, say the Gannett papers (which include USA Today). What’s striking from the story, however, is how small and rare the cost overruns really are.
The papers found overruns in 19 states, but they focused on projects that actually had overruns and did not reveal how many projects had no overruns. Of the overruns they found, many were less than 2 percent, most were less than 5 percent, and only three–in New Jersey, New York, and Ohio–were more than 10 percent. The unweighted average was around 7 percent. Since Gannett did not discuss any projects that had zero overruns, the real average must be much less.
This contrasts sharply with rail transit cost overruns, which have steadily averaged around 40 percent. Nearly 10 years ago, Bent Flyvbjerg reported that transit cost overruns in the United States averaged 41 percent while highway overruns averaged 8 percent. More recent research has found similar rail overruns, but the Gannett analysis suggests that highway overruns remain well under 10 percent.
