Life Cyde Assessment of CO₂ Emission from Inter-city Motorways by Road Cross-sectional Structure

Abstract

This paper proposes a method for the comprehensive assessment on cross-sectional structures of inter-city motorways in terms of CO₂ emission. The index employed in this study is the “Extended Life-cycle CO₂ (ELC-CO₂)” emission from highways. This takes into account of not only the CO₂ generated by highway construction and maintenance works, but also the CO₂ emission by traffic, which varies by highway cross-sectional design. Such traffic flow characteristics as traffic flow variations and/or speed-flow relationship is also investigated, which has not been considered in the conventional studies on LCA. The CO₂ emission by highway construction and maintenance works is estimated using “combined method”, for elevated, mounded, and tunnel sections respectively. Furthermore, various cross-sectional structures by several geographical and land-use conditions are assessed, through the calculation of ELC-CO₂ from each alternative.