Road construction is a significant contributor to greenhouse gas emissions within the transport sector. This study attempted to quantify the Green House Gases (GHGs) emission of Pokhara - Mugling Road with the help of Life Cycle Assessment (LCA). A Gate-to-Gate LCA was conducted to quantify emissions. This approach examines only the stages within the construction process, from the arrival of raw materials on-site to the completion of pavement construction. Sensitivity analyses were conducted to assess the differential impacts of bitumen and aggregate on emissions during construction. The Relative Importance Index (RII) was calculated by distributing a questionnaire to experts and environmental safeguard specialists to gather insights on the most suitable mitigation measures for the road sector in Nepal. The findings revealed that the total carbon equivalent emissions from the construction of the Pokhara - Mugling Road amounted to 33.73 kilotons of CO2e. Notably, 60.78% of these emissions were attributed to the materials used in the construction process. Fuel consumption by the Hot Mix Asphalt (HMA) plant contributed 70% of the emissions from the total fuel consumption, surpassing the emissions from all other plants and equipment involved in the pavement construction. Sensitivity analysis results indicated that changes in bitumen content have a more significant effect on GHG emissions compared to variations in aggregate. This suggests that the construction of a national highway substantially contributes to carbon emissions, and therefore, requires careful consideration to minimize its environmental footprint. Firstly, implementing effective construction and quality management plans is essential for reducing emissions. Equally important is the careful selection of construction materials and the exploration of alternative energy sources to minimize environmental impact. Using alternative materials such as rubber asphalt, reclaimed asphalt pavement (RAP), bio- bitumen and alternative energy sources such as natural gas, hydroelectricity and bio-diesel can significantly reduce emissions. Improving construction practices by adopting warm, or cold asphalt manufacturing techniques that require less energy, using electrical equipment, and implementing recycling technologies can reduce emissions. By adopting these sustainable practices, the contribution by road construction to greenhouse gas emissions can be substantially reduced in Nepal.

Keywords

Life Cycle Assessment, Gate to Gate, Green House Gas, Hot Mix Asphalt, Bitumen

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