Impacts of high-speed rail projects on CO2 emissions due to modal interactions: A review

This paper reviews existing literature on the CO2 emissions implications of high-speed rail (HSR) projects due to its interactions with air, road, and ordinary-speed rail. We conceptually classify the studies into three levels, with the first focusing on the emission comparison between HSR and the other modes, the second on the emission implication due to HSR-induced traffic reallocation, and the third on the life cycle assessment (LCA). We find that the literature is still in a relatively premature state. We also identify future research opportunities, including: i) to carry out a more detailed and comprehensive analysis regarding how HSR affects cargo operations of other transport modes and the corresponding CO2 emission implications, ii) to further develop the game-theoretical models to be applied to estimate a fuller picture of modal splits and the corresponding CO2 emission impacts, and iii) to apply LCA by considering the avoided life-cycle emissions associated with infrastructure and vehicles due to traffic diversion and the intricacies of modal interactions.

Automated summary

This paper reviews the CO2 emissions implications of high-speed rail projects in comparison to other modes of transportation, and classifies existing studies into three levels focusing on emission comparisons, traffic reallocation effects, and life cycle assessments. The literature is still in a premature state, with future research opportunities identified for more detailed analyses on cargo operations, game-theoretical models, and applying LCA to assess the intricacies of modal interactions on CO2 emissions.