ICT researchers develop the first regional road life-cycle assessment tool

By Waad Ayoub

Road vehicles are major contributors to greenhouse gas pollution. The U.S. transportation sector consumes 28 percentof the nation’s energy – 92 percent of which is petroleum-based – and is responsible for 27 percent of emissions. But what about the pavement itself? A significant amount of energy is required to obtain paving construction materials. In addition, the method by which a pavement is constructed, rehabilitated and maintained, used throughout its life cycle, and recycled at the end of its service life all have a great impact on the environment.  

To more effectively measure the environmental impact of pavement throughout its life, it is useful to use a comprehensive life-cycle perspective. Life-cycle assessment (LCA) tools assess every stage in the lifespan of a roadway or a bridge – from the use of materials to construction, maintenance and repairs, as well as disposal or recycling. The assessments gather energy consumption data during each stage of the pavement life, which assist in tracking, monitoring, and evaluating the environmental impact. This process includes development of models for estimating energy use resulting from vehicle tires, pavement traction and work zone delays, among other factors.  

Special attention is given to the use phase as most energy consumption and resulting emissions occur during pavement use, especially on roads with high-traffic volumes. The information from a life-cycle assessment can be used to evaluate the environmental impact of any roadway or roadside asset throughout its life cycle, quantitatively rate a project’s impact on the environment and demonstrate sustainability performance to stakeholders and the public, recommend best practices, and move toward a roadway system that is more sustainable.

The Illinois Center for Transportation (ICT) partnered with the Illinois Tollway, Applied Research Associates, and theRightenvironment to develop a comprehensive, regionalized LCA tool – the first of its kind. All roadway and roadside assets of the Illinois Tollway, including pavements, bridges, drainage, landscape and lighting, were covered in the tool, which allows quantification of emissions based on local data and provides owners, designers, consultants and contractors with more complete data sets, thus leading to better-informed, environmentally responsible decisions.

The broad impact of this research will be to help the Illinois Tollway ensure that its 15-year, $12 billion capital program, Move Illinois: The Illinois Tollway Driving the Future, is the cleanest and greenest in its history. Used together with the qualitative Federal Highway Administration’s Infrastructure Voluntary Evaluation Sustainability Tool (INVEST), the developed LCA tools enable the Tollway to quantitatively compare current construction projects with similar projects built previously under older standards and use that information to make informed decisions for future projects.

“The Illinois Tollway is committed to making environmental responsibility and sustainability part of everything we do – from planning to construction to maintenance,” said Illinois Tollway Executive Director Greg Bedalov. “As part of this commitment, we are using these innovative tools to monitor the environmental impact from the time new roads and bridges are built until the end of their useful life many decades later, which will not only help us better integrate sustainable practices into our construction projects, but will also allow us to evaluate their effectiveness and measure improvements during construction and beyond.”

In addition to these benefits, the development of more sustainable practices will optimize the use of recycled materials while enhancing roadway performance, thereby limiting the use of natural resources. Road users also will save millions of dollars’ worth of fuel and vehicle repairs, thanks to the improved riding quality of the roads they drive on. 

“The development of such a comprehensive life-cycle assessment tool for transportation infrastructure will help agencies, designers, and contractors build cost-effective and sustainable transportation structures while meeting community needs and building long-lasting transportation infrastructure,” said Imad Al-Qadi, Founder Professor of Engineering in the Department of Civil and Environmental Engineering (CEE) and director of ICT, who led the research team on this project. Other faculty serving on the project included CEE professor Jeff Roesler, associate professor Yanfeng Ouyang, assistant professor Jeremy Guest, and research assistant professor Hasan Ozer.

 

At top: A screenshot of the opening page of the life-cycle assessment tool showing the complete set of life-cycle stages considered in the software.