LCA+: Moving LCA into the Pavement Design Space
Paper in proceedings, 2012
The construction, operation, and maintenance of the United States roadway system are responsible for substantial energy and resource consumption. The current system of paved roads in the United States handles a volume of traffic on the order of 8 billion vehicle-miles per day. Due to high energy demand, road transport contributed the most greenhouse gases (GHGs) of any transportation mode in 2007, accounting for 83% of emissions from the transportation sector and 27% of all emissions in the United States. Improving the sustainability of this network requires better technical and decision making strategies starting with the design stage of pavements.
While the Mechanistic-Empirical Pavement Design Guide (MEPDG) is being adopted as a design tool throughout the U.S. it lacks the ability to take into account the environmental impacts of pavement systems. Hence, it is necessary to incorporate the performance designs of MEPDG with an environmental assessment tool to merge the structural and environmental aspects of pavement design.
The environmental impact of pavements throughout their lifetime is calculated using the life cycle assessment (LCA) technique. Conventional environmental assessments of pavements often overlook use phase related emissions, leading to conclusions based on incomplete results. Studies have empirically shown that an important factor in the life cycle assessment of pavements is the pavement-vehicle interaction (PVI) which describes the effect of pavement properties on vehicle fuel consumption. However, the results of these studies are not conclusive and cannot be generalized to all pavement designs.
This research uses a mechanistic approach to rationalize PVI and creates a link between pavement properties and their impacts on fuel consumption. Moreover, a network-level analysis has been performed using the Long Term Pavement Performance (LTPP) program’s databases to calibrate and validate this model. Finally, life cycle assessment is taken into the design space by incorporating MEPDG designs with LCA principles, taking into account the effect of PVI over the pavement’s lifetime. Moreover, evaluation of high performance sustainable pavement systems is enabled by extending the realm of MEPDG to model-based LCA principles. Through this approach, pavement design is enhanced structurally and environmentally constructing the necessary foundations for LCA+.