From Bloomberg Businessweek - States Roll the Dice on Highway Traffic (December 16, 2013):
"Traffic forecasts done by consultants for states and investors have long proven overly optimistic. The first-year revenue of 26 public and private toll roads that opened form 1986 to 2004 averaged one-third less than projected, according to a 2009 analysis of federal data by Robert Bain, a transportation consultant. U.S. miles traveled peaked in 2007 at 3.03 trillion,, then declined 2.5 percent through 2012, according to the Federal Highway Administration. "You never see a consulting report be negative or else they won't be able to sell the bonds," says Howard Cure, managing director of municipal bond research at Evercore Wealth Management."