(The following is a reproduction of an article from the Federal Highway Administration’s Office of Technology Applications June/July 1999 on-line issue of FOCUS. FOCUS is a monthly newsletter about projects of the Strategic Highway Research Program. The article is reproduced with the permission of Ms. Kathryn Harrington-Hughes, editor of FOCUS.)

As the most successful race car driver in NASCAR (National Association for Stock Car Auto Racing) history, Richard Petty is known as the king of the asphalt oval. Now, as star of a new Federal Highway Administration (FHWA) videotape, Smoother Pavements: Highways Fit for a King, he’s headlining a campaign to achieve smoother asphalt pavements nationwide.

Developed by FHWA’s Western Resource Center, in cooperation with the Arizona Department of Transportation (DOT), the video describes Arizona DOT’s pavement smoothness program. Under the program, the State inserts a smoothness clause into highway contracts, which provides incentive payments for pavements that meet a specified standard of smoothness.

“After several contracts with the smoothness clause had been completed,” says Jim Delton of Arizona DOT, “we were able to show contractors that they could obtain significant incentive payments by using the new technologies and equipment available today.” Some contractors have earned as much as $280,000 in incentive payments. “We consider that money well spent because we’re getting much better final smoothness levels than we ever achieved in the past,” says Delton. And in an unexpected bonus, some contractors are reducing their up-front bid price, with the expectation of earning an incentive later.

Arizona DOT and its contractors have found that the simplest, least expensive way to improve pavement smoothness is to maintain a more continuous, uninterrupted paving process instead of stopping and starting, which can result in bumps in the mat. For example, crews should make sure that the paving machine always has hot mix in front of it, so that there’s no need to stop and wait for another load. Smoothness can also be improved by making sure that the steel wheeled rollers are clean, track straight, and stay on the mat. If the roller is not 100 percent on the mat, it could pick up material on the edge of the roadway and transfer it to the new surface. And while improving paving operations is key to achieving smoother pavements, the asphalt plant also has an important role, keeping the temperature of the hot mix as consistent as possible and preventing mix segregation.

By introducing the smoothness specification, “we have changed the state of the art, ” says Delton. “The smoothness specification encourages innovation and quality work from contractors.”

The video was originally slated for distribution only in western States, but FHWA’s new national focus on improving pavement smoothness means that distribution has broadened to include transportation departments and contractors across the country, as well as such organizations as the National Asphalt Pavement Association.