A comparative life cycle assessment (LCA) of the construction of the third section of the Tehran-Shomal freeway: Largest road construction project in Iran

The construction of the Tehran-Shomal Freeway is a major infrastructural project in Iran aimed at enhancing connectivity between Tehran and northern regions. This study evaluates the environmental impacts associated with the construction of the third section of this freeway. Using Life Cycle Assessment (LCA), this study evaluates the construction of four distinct spatial pathways of varying lengths, focusing on key environmental impact categories at both the midpoint and endpoint levels. The research emphasizes the construction phase and contributes a method that can be used to develop and analyze construction phase life-cycle inventories. The normalized results indicate that Human Carcinogenic Toxicity is the most significant contributor to environmental impacts across all scenarios, with the Tunnel subproject identified as the dominant source, followed by bridge construction. Machine operation, Portland cement, and electricity emerge as the primary contributors to environmental impact within the tunnel construction process. Among the evaluated scenarios, the S3 scenario stands out as the most sustainable option, exhibiting the lowest overall environmental impact. It achieves a global warming potential of 1,062,439 tons of CO₂ equivalent and a final score of 35.5 MPt. These results emphasize the critical importance of adopting optimized construction strategies to reduce the environmental footprint of transportation infrastructure projects. However, selecting the most appropriate scenario should extend beyond LCA outcomes to include economic, social, and ecological considerations. This integrated approach is essential to achieving a balanced and holistic decision-making process that supports sustainable development objectives.