LCCA and environmental LCA for highway pavement selection in Colorado

The roadway network in the USA earned a grade of D representing poor condition in the latest report card from the American Society of Civil Engineers. To maintain economic and environmental sustainability during the roadway network development and rehabilitation, it is critical to apply sustainable materials and intelligent design. A good estimation on project-level life-cycle costs and environmental impacts is one of the important steps in the highway investment decision-making process. This article examines the current life-cycle cost analysis (LCCA) practice employed by the Colorado Department of Transportation (CDOT) in their pavement investment decision-making process, and proposes a regional environmental life-cycle assessment (LCA) model to evaluate the greenhouse gas (GHG) emissions associated with Colorado highway pavements. Both LCCA and LCA are performed for a highway reconstruction project with Portland cement concrete pavement (PCCP) and hot-mixed asphalt (HMA) alternatives. The LCCA is 7.4% in favour of HMA. Since the difference is less than 10%, it indicates equivalent designs. However, in the LCA, the GHG emission from PCCP is 26% less than the HMA over the 40-year analysis period. The vehicle fuel consumption will increase due to the deterioration of pavements. But the increased user cost is not included in the current LCCA employed by CDOT as well as user cost due to crashes and nonuser costs. The LCA can be an optional criterion for the selection of the preliminary pavement type.