Establishing benchmarks to determine the embodied carbon performance of high-speed rail systems

The extensive construction of high-speed rail (HSR) has led to considerable embodied carbon emissions, threatening carbon reduction targets and necessitating effective governance. Previous studies have focused on the carbon accounting of HSR, providing only pre-evaluation information for management. To measure the carbon emission level of HSR and guide improvements, it is essential to establish quantified carbon emission benchmarks as “yardsticks” for decision-making comparisons. Hence, this study proposes a data-driven method for determining the embodied carbon emission benchmarks of the HSR system, involving dataset construction, carbon accounting, statistical analysis, validation, and uncertainty assessment. Based on a dataset comprising 1226 HSR subprojects in China, a classified and graded HSR embodied carbon emission benchmark system is constructed, and the underlying causes for the emission differences among categories of HSR subsystems are explored. In addition to providing various benchmark values, the research results also demonstrate the decarbonization potential of advanced HSR construction technologies such as ballastless tracks, long-span box girders, and shield tunneling methods. Overall, this study can provide a decision basis for evaluating the HSR emission performance and offer insights into the selection of emission reduction technologies, thereby facilitating the low-carbon sustainable development of HSR construction.