ABSTRACT
Construction is a big contributor to carbon footprint emissions. The carbon footprint emissions in the construction stage are mainly from the construction materials and the construction activities. Among various construction processes, tunnel construction produces a significant amount of carbon emissions since it utilizes various types of high energy-consuming equipment. In order to identify and mitigate such carbon emissions of a tunneling project, it is required to reliably estimate carbon footprints of a tunneling project. The CO2 emissions can be calculated by estimating the consumed fuel of equipment and transport (diesel, electrical energy) and materials, and then using the conversion factors to CO2, from well recognized organizations. The purpose of this paper is to evaluate carbon footprint emissions of different tunneling construction methods. It includes the material production, different excavation methods (drilling and blasting, road header or hydraulic breaker hammer, TBM), casting and lining, rock support and road work. The contribution of each stage to the total carbon footprint is discussed and different methods are compared. The results of this study can be used as basic data for establishing a CO2 emission reduction plan at construction sites.
