“Project estimates between 1910 and 1998 were short of the final costs an average of 28 percent,” according to The New York Times, summarizing our findings. “The biggest errors were in rail projects, which ran, on average, 45 percent over estimated costs [in inflation-adjusted dollars]. Bridges and tunnels were 34 percent over; roads, 20 percent. Nine of 10 estimates were low, the study said.”[7] The results for time and benefits were similarly bad.
