New Developments in the Debate on Pavement-Vehicle Interaction: The Impact of Pavement Design on Fuel Consumption

 

Traffic on I-95

FOR IMMEDIATE RELEASE - March 4, 2014

LAS VEGAS—The White House recently announced the development of fuel economy standards for heavy-duty trucks that will take us well into the next decade. However, it is time to look not only at the efficiency of cars and trucks on the road, but to the road itself for fuel economy and emission reductions.

The Massachusetts Institute of Technology (MIT) is bringing rigorous data to the debate on the role that pavement-vehicle interaction (PVI) plays in the environmental and economic costs of the nation’s roadways.

Research by the MIT Concrete Sustainability Hub (CSHub) shows that PVI—related primarily to road stiffness and roughness—has a measurable effect on vehicle fuel consumption. That effect is significant over time and thus essential to the analysis of the lifetime environmental impacts of road projects using life cycle assessment (LCA) tools.

The United States’ transportation network is responsible for about one-third of national energy consumption and greenhouse gas emissions. As the network ages, the impact of PVI on greenhouse gas emissions worsens. Meanwhile, infrastructure funding remains significantly below what is required to improve conditions and performance. With the Highway Trust Fund forecast to go bankrupt next year, these findings bolster the case for increased infrastructure spending as Congress prepares to debate a new long-term transportation bill.

To ensure the sustainability of our roadways, policymakers and construction professionals must carefully analyze pavement designs’ cost and environmental impact throughout their entire lifespan by using life-cycle tools during the planning stages of road projects. For LCA to be effective, it must be based on the most accurate models possible, including those that analyze the effects of PVI.

The PVI debate stems largely from the variability in previous experimental investigations of fuel consumption on different pavement types. The CSHub’s models help illuminate the key drivers of PVI and allow pavement engineers to incorporate them into their design decisions. They have been used to predict that stiffer pavements could reduce fuel consumption up to 3 percent for the U.S. pavement network—a savings that could add up to 273 million barrels of crude oil per year. This would result in an accompanying annual decrease in CO2 emissions of 46.5 million metric tons.

CSHub researchers also evaluate the impact of pavement roughness on fuel consumption. A sample case study showed a significant impact on fuel consumption due to roughness—an increase of 30,000 gallons of fuel per mile over a 14-year test period. Other academic institutions as well as some state departments of transportation are conducting experiments that will help to validate and refine MIT’s PVI-related research. MIT is collaborating in several of these efforts.

Photo courtesy of Virginia Commonwealth University Capital News Service

 

PVI Fact Sheet

Context

The American Society of Civil Engineers gives United States roads a grade of D and reports that congested highways cost roughly $101 billion in wasted time and fuel annually.

The United States’ transportation network is responsible for about one-third of national energy consumption and greenhouse gas emissions.

Findings

The MIT Concrete Sustainability Hub (CSHub) has quantified fuel consumption due to PVI—primarily associated with road stiffness and roughness—and has demonstrated that the environmental impacts are significant for pavements over time.

Incorporating PVI models into life-cycle analysis tools will make those tools more accurate and help transportation agencies design roads with lower environmental impacts.

CSHub models predict that stiffer pavements could reduce fuel consumption up to 3 percent for the U.S. pavement network—a savings that could add up to 273 million barrels of crude oil per year. This would result in an accompanying annual decrease in CO2 emissions of 46.5 million metric tons.

A CSHub case study of pavement roughness showed a significant impact on fuel consumption due to roughness—an increase of 30,000 gallons of fuel per mile over a 14-year test period.

Verification and Implementation

Numerous experimental studies have demonstrated that there is additional fuel consumption due to PVI. One of the most recent studies was conducted by Florida International University.

The University of California Pavement Research Center is leading a new collaborative effort to review existing PVI models, including MIT’s.

MIT is collaborating with several departments of transportation in the U.S. to evaluate the environmental impacts due to PVI at the pavement network level.

 

The Concrete Sustainability Hub (CSHub) is a research center at the Massachusetts Institute of Technology (MIT) that launched in 2009 in partnership with the Ready Mixed Concrete Research & Education Foundation and the Portland Cement Association (PCA). The CSHub comprises a dedicated team of interdisciplinary researchers from several MIT departments working on concrete and infrastructure science, engineering, and economics. It brings together leaders from academia, industry, and government to develop breakthroughs using a holistic approach that will achieve durable and sustainable homes, buildings, and infrastructure in ever more demanding environments.

The mission of the RMC Research & Education Foundation, based in Silver Spring, Md., is to support research and educational programs that will increase quality, professionalism and environmental stewardship in the ready mixed concrete industry for the benefit of the citizens of the United States.

The Portland Cement Association, based in Skokie, Ill., represents cement companies in the United States and Canada. It conducts market development, engineering, research, education, and public affairs programs.

 

 

 

Dr. Jeremy Gregory is a research scientist and the executive director of the MIT Concrete Sustainability Hub. He studies the economic and environmental implications of engineering and system design decisions, particularly in the area of materials production and recovery systems. Research topics include product and firm environmental footprinting, manufacturing and life-cycle cost analysis, and characterization of sustainable material systems. He has applied these methods, often with industry partners, to a range of different products and industries including pavements, buildings, automobiles, electronics, consumer goods, and waste treatment and recovery.