LCC Model for Evaluating the Sustainability of Bridge Decks: A Comparison of Conventional Concrete Joints and Engineered Cementitious Composite Link Slabs [thesis]
A life-cycle cost (LCC) model was developed to evaluate the sustainability of bridge decks. This study compared two bridge deck systems: one with conventional concrete (CC) joints, the other with engineered cementitious composite (ECC) link-slabs. The ECC system is modeled as having a service life double that of the CC system. A lifecycle inventory (LCI) and traffic flow (TF) model, developed by researchers at the University of Michigan, served as the foundation for the LCC model. The LCC model included agency and social costs. Agency costs consisted of material, construction, and end-of-life costs, while social costs were comprised of emissions damage costs from agency activities, and vehicle congestion, user delay, vehicle crash, and vehicle operating costs. These costs were estimated across all life-cycle stages (material production, construction, use, and end of life), over a 60-year analysis period.
For the base case, the ECC system had lower life-cycle costs than the CC system ($1.7 million vs. $2.0 million) - this difference represents a 15% cost advantage for the ECCsystem. The ECC system also had lower agency and social costs than the CC system, and lower life-cycle costs for each stage compared to the CC system. The agency and user costs were discounted at 4%; the discount rate for emissions damage costs declined over time from 4%. For both systems, agency costs ~40% while social costs ~60%.
Four additional scenarios were investigated by altering the annual average daily growth rate (AADT) and the percentage of vehicles pursuing detours. The ECC cost advantage for these four scenarios ranged from 19% to 56%. Agency/user discount rates of 1% and7% were tested, as were emissions damage cost discount rates of 0% and 4%; ECC had lower life-cycle costs for all sensitivity analyses. Both systems were dominated by user costs, which represented half, or more, of all costs for both systems; these were driven by user delay and vehicle operating costs. Emissions damage costs were small for both systems. AADT growth rate had a large impact on results, unlike the detour assumptions.
Chandler, Richard. 2004. Life-Cycle Cost Model for Evaluating the Sustainability of Bridge Decks: A Comparison of Conventional Concrete Joints and Engineered Cementitious Composite Link Slabs. Master's Thesis, University of Michigan, Ann Arbor: 1-101.