CAMBRIDGE, Mass.--Researchers at the Massachusetts Institute of Technology (MIT) have found that a pavement property called deflection could save more that $15 billion in annual fuel costs and reduce greenhouse gas emissions.
A study released today focuses on the interplay between a vehicle and the road, and how that interplay can affect fuel consumption. Known as pavement-vehicle interaction, it is seen in three forms: roughness, texture and deflection.
The report, titled "Where the Rubber Meets the Road: Estimating the Impact of Deflection-Induced Pavement-Vehicle Interaction on Fuel Consumption," focuses on deflection. Deflection refers to the small dent in the pavement that a car creates as it moves down the road. This dent creates a slight but constant uphill climb, which burns more fuel. The effect is similar to walking on sand. With each step, your feet sink and create a dip.
Concrete pavements, inherently stiffer than asphalt, can reduce a car's "footprint" and gas costs.
By reducing the environmental footprint of our pavement systems, MIT researchers hope to achieve a more sustainable national infrastructure.
"The goal is to better understand the environmental impact of the roads we drive on every day," says Professor Franz-Josef Ulm, the George Macomber Professor in MIT's Department of Civil and Environmental Engineering.
"How does the interaction between the road and vehicle affect fuel consumption? The answer could lead to a new strategy for significantly improving fuel efficiency and reducing transportation emissions."
In a previous study, MIT researchers found that using stiffer pavements decreases deflection and reduces fuel consumption by as much as three percent -- a savings that could add up to 273 million barrels of crude oil per year, or $15.6 billion.
Reducing fuel consumption is an important aspect of climate change mitigation, according to the report. The U.S. transportation sector alone burns more than 174 billion gallons of fuel each year, making up 27 percent of total greenhouse gas emissions, as well as contributing to human health concerns like smog.
"While the use of fossil fuel-based transportation may be inevitable," says the MIT report, "Improving fuel efficiency can create big change -- for example, a one percent reduction in fuel consumption could cut greenhouse gas emissions by up to 15.5 million tons of carbon dioxide per year."
The model developed by MIT estimates deflection based on a pavements materials and structure. It can also be used to estimate the fuel consumption of various types of vehicles, providing a framework for environmentally friendly design and maintenance decisions by public officials.
Current ways to improve fuel efficiency include upgrading to higher efficiency vehicles or maintaining proper tire inflation - all of which are difficult to standardize . But improving fuel efficiency through the design and maintenance of roadways can be controlled by governmental agencies that set standards and policies for construction of our streets and highways.
A copy of "Where the Rubber Meets the Road" is available here.
Additional information on MITs work on pavement design and fuel consumption is available here.
The Concrete Sustainability Hub is a research center established at MIT in collaboration with the Portland Cement Association and the Ready Mixed Concrete Research and Education Foundation.