WASHINGTON — By 2015 U.S. governments at all levels will need to more than double their spending on highways and bridges to keep up with increased traffic, freight congestion, the demands of aging highways and bridges, and the growth of the nation’s population.

These findings, among others, are included in the Bottom Line report, released last week by the American Association of State Highway and Transportation Officials (AASHTO) and the American Public Transportation Association and presented to Congressman James Oberstar (D-Minn.), chairman of the House Transportation and Infrastructure Committee.

Smoother roads, less time lost to congestion, improved transit service and substantial savings in vehicle owner costs are the benefits citizens can expect in exchange for this investment.

In 2006, federal, state and local governments spent $79 billion on highways and bridges. However, investment of $166 billion a year is required, if the number of miles driven increases at an expected rate of 1.4 percent a year.

The report found that the value of freight transported in America was $15 trillion.

Freight volumes are expected to grow by 80 percent by 2035. In addition, between 1980 and 2005, international container traffic through United States ports grew six-fold. In 2006, 42 million containers were shipped and by 2020, the number of containers moving through U.S. ports could reach over 100 million.

"We are a growing nation, adding 150 million people every 50 years," said John Horsley, AASHTO Executive Director. "To meet the nation’s needs we must preserve the highway and transit systems built over the last century and add capacity to keep America competitive in the world economy and meet growing mobility needs here at home."