The estimates have been off by a wide margin for the past seven years, the Washington Post reported. For instance, the U.S. Department of Transportation forecasted Americans would drive 3.3 trillion miles in 2012, which was almost 11 percent higher than what they actually drove.
The Federal government reaches its overall estimates based on the approximations of state and local entities, according to the State Smart Transportation Initiative.
Why does overestimating miles driven matter? State and local governments allocate money for building new highways and roads based on those estimates. Funding may be lost on large highway construction projects for unrealized traffic when it could go to cheaper, walkable streets that raise property values and quality of life. States relying on taxes from gasoline sales to fund road maintenance and construction projects could also find themselves short due to the overestimates of miles driven.
Other studies have found a sharp decline in driving. Last month, the U.S PIRG compiled data from the Federal Highway Administration, Federal Transit Administration and U.S. Census to find commuting in private vehicles declined in 99 of the 100 largest urban areas in America since 2000. PIRG also found that the percentage of homes without cars had increased in 84 of the 100 largest markets between 2006 and 2011. The rise of telecommuting, the weak economy, aging baby boomers retiring from work and underemployed Millennials have all been cited as reasons for declining car use.