So far this blog has been talking about road transportation a lot. What about railway then? In many places (such as China), railway is not just one major way of moving cargo around, but also large amounts of people. And by this I mean a scale comparable to, or even greater than, domestic civil aviation. Take the high-speed train system in China as an example, this entirely electric-powered transportation system dedicated to passenger transportation shares almost an equal market with domestic airlines. Pan & Truong (2020) greatly summarized the competition advantage of Chinese High-Speed Train against low-cost carrier airlines. Now what about the externality associated?

Extensively, past studies on externalities of railway, regardless of the kind of power that trains rely upon, have been on positive externalities such as time saving for both commute and cargo transportation (Lv & Zheng, 2014; Chen & Wei, 2018), and on more tangible negative externalities such as noise pollution (Diao et al., 2016). Although relevant studies date back before 1978 (Poon, 1978), railway externality studies seldom touch on environmental and climate externalities that are not immediately felt. Similar to de-icing externalities discussed in previous blog posts, railway systems have become more or less of a necessity in many countries that to consider the non-tangible externalities of railway systems may come at an economic cost too high that such externality analysis becomes undesirable.

Yet in the long term, neglecting environmental and climate externalities arising from railway systems may cost global adaptation efforts of a scale beyond economic revenues of railway systems. Hardly is there any emission standards or emission reduction studies considering internal combustion locomotives, while electric trains are usually considered as “clean”. In terms of emission intensity covering the same distance, railway transportation indeed results in larger amounts of green house gas emissions than that of road transportation, with number of passengers on board actually playing only a minor role (Rybicka et al., 2018). Very necessary it is, therefore, to promptly establish suitable emission standards and emission reduction schemes, especially for internal combustion locomotives.

For electric railway systems, emission intensity varies greatly with regional electricity sources. Consider the high speed train system in China. High-voltage powered high speed trains do consume a lot of electricity - and as a country running (still) mostly on coal, China supports its high speed railway system mainly by fire-power plants. This means, of course, immense GHG and pollutant emission on the upper stream of the railway system itself. So far, passengers have not been paying for this pollution, nor are the railway carrier companies. Yet on the other hand, electric railway systems do not enjoy the flexibility of actively adjusting emission intensity levels as do fuel-burning railways. Most recently, academics have been proposing new methods by which emission reduction can be achieved without waiting for large scale renewable electricity sources. By modifying train consolidation centres for international railway corridors and operation ranges, it is possible to reduce the amount of trains running on the system at any given time, while maintaining similar transportation capability (Cheng et al., 2021). Not only can renovated operation scheme reduce railway congestion and overall power burden, but also can the railway system save itself considerable amount of green house gas emission potential (fig.2). It is also likely that re-arrangement for the domestic high speed railway system can yield similar emission reduction effects.