Eco-decision Making for Pavement Construction Projects.

Abstract

Life cycle assessment (LCA) is a promising approach that can be used to quantify environmental impacts for selected products within defined system boundaries. Although LCA has begun to be applied to pavement systems, the practice is in its infancy and, as yet, rather ill-defined. Existing pavement LCAs methods and tools are not adequate or consistent in terms of system boundary, data quality, and transparency. Currently, it is not practical to expect pavement practitioners to conduct their own LCAs because of the specialized knowledge and extensive time required. However, an appropriate LCA software tool, intended for use by pavement practitioners, could assist in performing LCAs and allow pavement LCA to become a low-cost standard practice capable of providing valuable accounting and decision support. This research established an LCA framework and a robust data inventory for pavement LCA that is both deterministic and probabilistic. An Excel-based tool, Roadprint, was developed for this proposed framework and data inventory. This tool can facilitate knowledge that will (1) implement pavement LCA in a standardized and reproducible manner, (2) conduct probabilistic analysis, and (3) generate well-analyzed presentations of results to interpret LCA outputs. Raodprint was assessed using six standard pavement designs, three case studies, and four other pavement LCA tools. This assessment showed: (1) Roadprint is capable of differentiating various parameters, to delineate projects conditions, and it is superior to other tools in terms of scope, system boundary, and data quality. (2) Improving the material production processes would be the most effective way to mitigate overall environmental impacts of pavement construction. (3) Users of LCA results should be aware of whether feedstock energy is included in the result, because it can increase reported energy consumption two to threefold. (4) Comparisons results from different LCA tools can be misleading because the differences in tools could overwhelm the differences in actual processes. (5) It is essential to match the scope, system boundary, and data quality of the LCA tool being used to the goal of an LCA comparison or accounting. In summary, Roadprint can help researchers, policy makers, and engineers make better decisions prior to the implementation of environment-significant and costly pavement projects.