In a previously reported version of this press release, it was stated that improvements to smoothness of pavements could save 5 billion gallons of fuel. However, the National Asphalt Pavement Association (NAPA) has corrected its previously released press release with these numbers. The corrected numbers, as stated in the NAPA story below, are 3.3 billion gallons of fuel (2.4 billion gallons of gas, 900 million gallons of diesel) could be saved. The dollar value of the savings was reported correctly in the original release: $12.5 billion a year.

A new study shows that one road to energy savings could already be under the wheels of our cars: smoother pavements, according to the National Asphalt Pavement Association (NAPA).

Dr. Richard Willis, an assistant research professor at Auburn University, reported on July 19 that modest improvements in the smoothness of pavements could save up to 3.3 billion gallons of fuel (2.4 billion gallons of gas, 900 million gallons of diesel) gallons of fuel for the vehicles being driven on our highways. In other terms, smoothing out America’s roads and highways could save around $12.5 billion a year for the U.S. economy, NAPA reports on the study’s findings.

Willis and Auburn’s Dr. Rob Jackson have just completed an analysis of more than 20 studies from throughout the world. At the Midyear Meeting of the National Asphalt Pavement Association, Willis presented a preview of a study that will be published soon by Auburn. He reported that smoothness is a pavement characteristic that has one of the greatest impacts on fuel economy. “We know that, of all the factors that influence fuel economy – vehicle aerodynamics, engine dynamics, ambient air temperature, tire geometry, vehicle speed, tire pressure, and so forth – there is only one that pavements can affect, and that is rolling resistance,” said Willis.

Asked to define his terms, Willis said, “Rolling resistance can be thought of as the force required to keep tires rolling. It could also be thought of as the energy lost between the vehicle and the pavement. Of the two main influences on rolling resistance related to pavements – those due to the stiffness properties of the tire and those due to imperfections in the pavement surface – the pavement industry has the opportunity to influence only one, the pavement itself.”

Willis broke down his numbers.

“A study published by Schmidt and Ullidtz in 2010 showed that slight improvements in smoothness can reduce fuel consumption by 1.8 percent to 2.7 percent,” Willis said. “Other studies suggest larger reductions of up to 4.5 percent. The Bureau of Transportation Statistics says that vehicles traveling on U.S. highways consumed 168 billion gallons of gas and diesel in 2009.

“AAA reported last week that the average price of gas was $3.66 per gallon and diesel averaged $3.93,” Willis continued. “Using a conservative figure of a 2.0 percent reduction in fuel consumption, we could thus save 5 billion gallons of fuel, or $12.5 billion, every year.”