Optimizing carbon dioxide emissions in highway bridges: integrating life cycle assessment, and dynamic maintenance into a decision-support framework: case study in Hungary

Abstract Highway bridges produce substantial emissions, particularly during maintenance, undermining sustainable development goals. In real-world bridges, with many conflicting objectives, reformulating the optimization problem to independently address the environmental footprint in maintenance planning before introducing structural integrity, deterioration models, and costs, remains unexplored. The aim of this paper is to integrate life cycle assessment (LCA), infrastructure management, and dynamic maintenance to minimize the environmental impact of highway bridges. First, maintenance-phase LCA is conducted in conformity with ISO 14040 and ISO 14044. Environmental impacts are assessed using Global Warming Potential. Next, CO 2 -critical activities are identified, and the primary inputs of the optimization process are the life cycle outputs (environmental impacts), maintenance frequency, and gaps between maintenance rounds. This approach is implemented in Python and applied to a Hungarian highway bridge case study. The results showed that trench lining, surface repair of concrete structures, and modified bitumen sheet insulation are the top three most CO2-intensive activities. The optimal dynamic maintenance schedule for a four-round maintenance at years 5, 8, 11, and 23 reduced CO2 emissions by 15.9% compared to the baseline fixed 5, 10, and 30 years schedule. The reduction value ranges from 6.8 to 25.0% depending on the uncertainty analysis. More frequent maintenance (five or six rounds) demands unrealistic short intervals to produce feasible solutions. The conducted sensitivity analysis confirmed that balancing maintenance frequency and interval choice strongly affects the reduction ratio. The developed framework enables practitioners to make environmentally aware, flexible decisions throughout the infrastructure's life.