Environmental load estimating model of NATM tunnel based on standard quantity of major works in the early design phase

Amid such international responses to climate change, there is a need to assess environmental loads and to develop an evaluation technique for reduction of greenhouse gas emissions and pollutants in the construction industry. Actual construction projects need to conduct a preliminary evaluation of environmental loads among alternatives in the early design phase. Since current methods are limited by requiring detailed design information, quick decisions are difficult to make. This study is to develop and validate the environmental load estimating model of NATM tunnel based on standard quantity of major works that can estimate the environmental loads by using information available in the early design phase. According to the validation result, the mean absolute error ratio was 3.7%. Moreover, comparing with the conventional basic unit method, it is found that the suggested model was more accurate. When estimating the environmental loads in the early design phase in which available information is limited, the proposed model will be useful to review environmental loads of alternatives in advance.