Life cycle assessment of RCC bridge for environmental impact evaluation: a case study

Abstract

Bridge construction activities significantly impact the environment due to the extensive use of materials and fuel-powered equipment, both contributing heavily to carbon dioxide (CO2) emissions. Life cycle assessment (LCA) provides a robust methodology for evaluating these environmental impacts throughout a bridge’s life span. This case study examines the environmental footprint of a reinforced cement concrete (RCC) bridge using a comprehensive LCA framework aligned with ISO 14040 standards and implemented through the One Click LCA tool. The selected case is an existing RCC bridge located in a densely populated urban area of Karachi, covering cradle-to-gate, operations, and maintenance phases. Construction phase data was gathered retrospectively, while maintenance impacts were estimated using scenario-based assessments supported by actual data from the contractor, consultant, and bridge authority. Operational emissions, including traffic-related carbon dioxide, were measured using carbon dioxide sensors and traffic counts. The total life cycle carbon footprint was calculated as 11 678 862.2 kg carbon dioxide-eq, with construction and maintenance phases contributing 11 676 493 kg carbon dioxide-eq, and fossil-based emissions alone accounting for 5 924 910 kg carbon dioxide-eq. Ready-mix concrete (26.4%) and reinforcement steel (24%) were the highest emission sources. The global warming potential category showed the greatest impact. The study emphasises adopting low-carbon materials, efficient design, and emission-reduction strategies for sustainable infrastructure.