On October 25^th 2021, Nature Climate Change, a sub-journal of Nature, published online the research results Impact of high-speed rail on road traffic and greenhouse gas emissions by Wu Jing, a tenured associate professor at the THU Department of Construction Management, and others. The study pointed out that after operating high-speed rail in China, parallel expressway traffic decreased, which reduced the transportation industry’s carbon emissions. At the same time, the “News and Views” column of Nature published a commentary article, The hidden benefits of high-speed rail, by Professor Armin Schmutzler from the University of Zurich in Switzerland, stating that this study is “the first contribution to the analysis of the effect of high-speed rail on the reduction of GHG emissions” and has provided “very important insights.”

Globally, high-speed rail networks in East Asia and Europe are relatively developed. Among them, China ranks first worldwide in terms of the total mileage of high-speed rail. As an essential means of passenger transportation in China in recent years, high-speed railways are carrying more and more transportation capacity. Although high-speed rail is generally considered more energy-efficient and environment-friendly than road transportation and traditional rail, few empirical studies have revealed the extent to which the newly opened high-speed rail network can reduce carbon emissions from the transportation industry. This study has filled this gap.

Development of High-speed Rail Network in China in 2008-2016

This study, making use of China’s national traffic monitoring data and statistical quantitative research methods, finds that the rapid development of China’s high-speed rail network has significantly reduced the volume of road transportation of passengers and cargo, thereby reducing GHG emissions by an equivalent of 11.18 million tons of CO2 each year, a figure that is equivalent to 1.33% of the total GHG emissions in China’s transportation industry in 2016. The realization of emission reduction is mainly due to the shift of cargo transportation from roads to traditional railways. This is because the transportation capacity of traditional railways is released as passengers transfer from traditional railways to high-speed rail and high-speed rail networks. The substitution effect on road traffic is the main source of the overall contribution of high-speed rail to GHG emission reduction. Further research finds that the environmental benefits of China’s high-speed rail have not been fully realized, which is mainly constrained by China’s thermal power-dominated generation structure. In the context of the “double carbon targets” of peaking carbon emissions by 2030 and achieving carbon neutrality by 2060, research forecasts indicate that as the proportion of clean energy increases in China’s power generation structure in the future, the emission reduction effect of high-speed rail will see great improvement.

Changes in GHG Emissions under Baseline Assumption and Other Assumptions

This study represents the joint efforts by Lin Yatang, Assistant Professor at the Department of Economics, Hong Kong University of Science and Technology, Qin Yu, Associate Professor at the Department of Real Estate, National University of Singapore Business School, Wu Jing, Associate Professor at the Department of Construction Management, Tsinghua University and Director of Hang Lung Center for Real Estate at Tsinghua University, and Xu Mandi, a doctoral candidate from the Department of Construction Management, Tsinghua University (in alphabetic order of surnames), and all the four are co-first authors. This study was supported by the National Natural Science Foundation of China.

Up to now, the research results of this article have been reported by China Daily, Science and Technology Daily, People’s Daily (English edition), and other official media, and reprinted by English.gov.cn (English edition), stdaily.com, Chinanews.com, the official website of China State Railway Group Co., Ltd. and other media outlets, drawing widespread attention.