Energy and emission impact quantification of pavement preservation using life cycle assessment

This study aims at developing a life cycle assessment (LCA) model to quantify the impact of pavement preservation on energy consumption and greenhouse gas (GHG) emissions. In the past, most of the research focused on the environmental impact of pavements at material and construction stages but ignored the usage stage. The construction stage analyzed in this study contains energy consumption and GHG emissions at material, manufacture, transportation and placement phases. Vehicle operating cost and fuel economy is affected by change in tire rolling resistance during usage stage. This also affects GHG emissions significantly. In this study the Highway Development and Management (HDM-4) model and the Motor Vehicle Emission Simulator (MOVES) were used to analyze fuel consumption and emissions caused by different vehicles on the pavements treated by different preservation treatments. Surface characteristics such as roughness, texture and deflection were taken into account in tire rolling resistance along with general factors such as speed, traffic volume, and road grade. Two pavement sections with different roughness from the long-term pavement performance (LTPP) database were used in the analysis to illustrate the importance of considering usage stage in LCA. The thin overlay was found to have the highest energy consumption and emissions among four preservation treatments during construction stage, but at the same time resulted in the greatest reduction of energy and emission at usage stage. If only construction stage is considered, energy and emissions are ruled by use of amount of material and manufacture process. The reductions of GHG emission at usage stage are much greater than the GHG emission produced at construction stage for all preservation treatments. Excluding the usage stage will omit the fact that construction stage has less impact on pavement LCA than usage stage. Combining both construction and usage stages gave a life-cycle impact of pavement preservation on energy and GHG emission. The results show that there is a significant amount of change in energy consumption and emissions when traffic factors and pavement surface characteristics are considered during usage stage. The study results provide valuable insights in selecting sustainable pavement maintenance strategies from an environmental view point.M.S.Includes bibliographical referencesby Rashmi Gangara