Calculation of endogenous carbon dioxide emission during highway tunnel construction: A case study

The endogenous CO₂ emissions are mainly from construction equipments powered with fossil fuel combustion at highway tunnel building period. These emissions from construction fossil fuel including gas, diesel, oil, coal and asphalt, are modeled and calculated to assess the effectiveness of highway construction. This paper selects a highway in western China as a case study to focus on the endogenous CO₂ emission during tunnel construction. It summarizes the results of field research that used a scientific literature. The formulary of counting methodologies of CO₂ emission considering the endogenous components is built up for highway tunnel construction. The oriented-diesel CO₂ emissions are at high level with the proportion of over 90% in comparison with other fuel types in tunnel building. The average endogenous CO₂ emission of tunnel construction is with the default value of 2911.5 kg/m. The research that produced these results should be continued to observe more highway tunnels of the same region in order to refine the current data and also gather data from other highways.