Dr. Richard Willis, assistant research professor at NCAT, commented, “We are reviewing numerous studies from around the world. One of the issues we are examining is to determine what pavement characteristics affect rolling resistance. Most studies indicate that smoothness, or conversely, roughness of the pavement is the dominant factor that affects rolling resistance.”
The study also will recommend an experimental plan to better quantify the effects of the key pavement factors on rolling resistance and vehicle fuel economy. Results from the study could be an important step in enabling engineers and contractors to design and construct more fuel-efficient asphalt pavements.
Dr. Howard Marks, NAPA’s Director of Environmental and Regulatory Affairs, said, “Although there has always been a question of whether pavement stiffness plays a role in vehicle fuel use, the researchers are now finding that the type of pavement – rigid concrete vs. flexible asphalt – has no significant bearing on fuel economy for vehicles traveling over our nation’s highways and therefore cannot be used as a basis for public policy. What is known, however, is that smoother pavements are more fuel-efficient.”
Dr. Marks also referenced a similar literature review currently being conducted by the Concrete Sustainability Hub sponsored by the National Ready-Mixed Concrete Association and the Portland Cement Association. The Concrete Sustainability Hub is located at MIT. “Given that MIT is examining similar data, we expect that results of both research organizations should be quite consistent in finding that the type of pavement (concrete or asphalt) has no measurable impact on fuel efficiency for vehicles using the highways.
“For more than 25 years, the asphalt industry has been supporting research that has resulted in pavements that are longer-lasting, smoother, safer, quieter, and more durable,” commented Dr. Marks. “We have learned that the impact of pavement smoothness on vehicle fuel economy is so striking that a high premium should be placed on constructing and maintaining smooth pavements.”
Dr. Marks pointed to the fact that many highway agencies have different smoothness standards for asphalt and concrete. “We think that the evidence regarding pavement smoothness and fuel efficiency is so compelling that all agencies should adopt identical smoothness standards for all types of pavement, both at the time of construction and when determining the timing of rehabilitation. This will result in fuel savings that will benefit the nation far into the future.”
