Economic and Environmental Evaluations of Life-Cycle Cost Analysis Practice: A Case Study of Michigan DOT Pavement Projects

Abstract

This thesis investigated the economic and environmental aspects of Life-Cycle Cost Analysis (LCCA) practiced by Michigan Department of Transportation (MDOT). From the economic perspective, it analyzed MDOT’s accuracy in projecting the actual costs over pavement service life and choosing the lowest-cost pavement alternative. The estimated and actual accumulated costs and maintenance schedules of ten highway sections were compared. From the environmental perspective, it incorporated pollution damage cost (an external cost element) which is currently overlooked by states DOT into LCCA. A life-cycle assessment model was developed to compare and monetize the environmental impact of asphalt and concrete pavement alternatives for thirteen MDOT projects. While results indicated that MDOT LCCA procedure correctly predicted the pavement type with lower initial construction cost, actual costs were usually lower than estimated in the LCCA. This outcome was partly because the cost estimation module in MDOT’s model was not site-specific enough. Refinements to its pavement construction and maintenance cost estimating procedures would assist MDOT in realizing the full potential of LCCA in identifying the lowest cost pavement alternative for the studied pavements. Alternatively, asphalt alternatives looked better than concrete alternatives in some environmental indicators (GHG, NOx, SO2 and Pb) but worse in others (energy, VOC and carcinogens), with material production as the major source of emissions. The pollution damage cost ranged from $1,900-$76,000/4-lanes-km, but the lowest-damagecost alternative varied across projects. More importantly, it contributed to only 0.8% to 9.2% of total life-cycle costs, and did not alter the results recommended in the original MDOT LCCA documents. Further expansion of the external cost boundary would make it more significant in LCCA.