This research investigates the integration of environmental costs into the cost-benefit analysis (CBA) framework for constructing circular viaducts. Circular viaducts offer environmental benefits but face challenges due to their higher initial construction costs. The traditional CBA framework focuses solely on economic costs, hindering the adoption of circular construction. This research proposes a methodology to monetize environmental costs and integrate them into the CBA framework to make informed decisions about circular viaduct construction.
The methodology involves analysing the environmental impact of circular viaducts and traditional viaducts using Life Cycle Assessment (LCA) and Environmental Product Declarations (EPDs). The environmental impact is then monetized using agreed-upon values from various stakeholders. The monetized environmental costs are incorporated into the CBA framework using cash flows and the net present value (NPV) method.
The research findings indicate that the implementation of circular viaducts is most viable in scenarios with longer lifespans. In these scenarios, the overall environmental costs of the circular viaduct are lower than those of the traditional viaduct due to the lower frequency of replacement. However, the NPV analysis reveals that the traditional viaduct has lower present value environmental costs in all three scenarios. This is due to the difficulty of accurately predicting future material prices, which could significantly impact the economic benefits of material reuse in the circular viaduct.
Results show that while the circular viaduct exhibits higher environmental costs in some scenarios, its economic benefits through material reuse, particularly in scenarios two and three, make it a more viable option. However, further research and development are needed to reduce the initial environmental and economic costs of circular viaducts to achieve a wider and faster adoption of this sustainable construction method.