On track
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In this report

Rail is one of the most energy-efficient transport modes, responsible for 9% of global motorised passenger movement and 7% of freight but only 3% of transport energy use. Urban and high-speed rail infrastructure has expanded rapidly over the past decade, laying the foundation for convenient, low-emissions transport within and between cities. China is leading the way in deploying high-speed rail with unprecedented expansion: passenger activity increased about 13% in 2019, more than twice that of domestic aviation. Further rail investments in India and Southeast Asia in particular can help get the transport sector on track with the SDS by displacing more emissions-intensive modes such as cars, trucks and airplanes.

GHG intensity of passenger transport modes, 2019

Tracking progress

While the share of rail passnger kilometres (pkm) travelled has been steady at slightly less than 10% since 2000 despite rapid rail infrastructure expansion, rail operations account for only 3% of transport sector energy use, which highlights the low energy intensity of this mode.

In 2019, rail services consumed 0.6 mbd of oil (0.6% of global oil use), around 280 TWh of electricity (1.2% of global consumption) and were responsible for about 0.3% of direct CO2 emissions.

Given the low energy and CO2 intensities of rail transport, promoting rail use is a promising strategy to enhance energy security and reduce emissions. Shifting passenger and freight transport activity from more intensive modes such as private cars, trucks and airplanes to rail would substantially reduce net energy use and emissions and make the Sustainable Development Scenario (SDS) more easily achievable.

As with all other transport infrastructure, rail investment is expensive. High passenger or freight throughput (i.e. high infrastructure utilisation) is necessary for a new rail project to pay off, both economically and environmentally. Shifting considerable transport away from cars, trucks and planes also has very important societal and environmental benefits that cannot be fully captured in conventional commercial pricing.

Costs and throughput capacities of urban transport infrastructure

Costs and throughput capacities of urban transport infrastructure
Costs and throughput capacities of urban transport infrastructure
Costs and throughput capacities of urban transport infrastructure

Rail infrastructure investment increased nearly threefold between 2005 and 2015, with most of this growth in China, whose share within a group of more than 40 countries has grown from less than 20% to more than 50% in the past decade.

Infrastructure for both urban and high-speed rail (HSR) has expanded with this investment increase, and China leads the way in both categories.

Passenger rail travel is the least energy- and CO2-intensive of all motorised transport modes. It is also the least oil-reliant by far: globally, about three-quarters of conventional passenger rail activity uses electricity, and the remaining one-quarter relies on diesel. Furthermore, virtually all urban (metro and light-rail) and high speed rail networks are electric, and electrification of conventional rail is expected to continue at a rapid pace.

Passenger rail networks are concentrated in a handful of regions – China, the European Union, India, Japan and Russia – that together register 90% of global passenger rail activity.

Despite rapid metro and high-speed rail system expansions in the past ten years, the rail share in global motorised passenger transport has remained roughly constant at just below 10% over the past two decades.

However, the share remained unchanged because these high rail investments happened during a decade of unprecedented growth in motorised mobility, proving that rail can keep pace in providing affordable, convenient mass transit even as incomes rise in emerging economies.

Using the full potential of rail transport to meet climate targets and Sustainable Development Goals (SDGs) means capitalising on the competitive advantages it has over other modes to raise passenger usage – even as rising incomes spur greater private car ownership and air travel.

Global line kilometers of conventional rail, 2000-2018


Global line kilometers of metro, light rail and high-speed rail, 2000-2018


Today, more than 900 billion pkm are travelled by high-speed rail every year, compared with 3 100 billion pkm by conventional rail.

Almost two out of three high-speed rail lines are in China: starting from virtually none only a decade ago, the country now has over 24 000 km. In 2019 alone, China National Railways opened two more high-speed rail corridors totalling 750 line km, and added more than 3 000 km of new lines. The rapidity of this rollout in China makes it one of the largest infrastructure projects in recent history, and total high-speed rail activity in China is catching up with domestic passenger aviation.

Long-distance domestic passenger activity in China, 2005-2018


Owing largely to China’s commitment, global high-speed rail infrastructure expanded 3.4 times between 2008 and 2018. The rate of annual average growth (13%) is historically unprecedented, but continuing investments could contribute substantially to attaining the SDS. Moreover, high-speed rail infrastructure growth – and the investments needed to realise it – will need to spread from China to other densely populated emerging economies such as India.

The Indian government is completing the land acquisition to construct a high-speed rail corridor between Mumbai and Ahmedabad, although the construction works that were to begin in April 2020 have not started yet. This corridor, totalling about 510 km, is the first of six high-speed rail lines the Indian government plans to build in the upcoming years to connect the largest Indian cities. Once realised, this impressive project could help to substantially limit the rise in emissions from India’s transport sector while ensuring fast and safe passenger movement throughout the country.

Nearly 200 cities worldwide have metro systems, their combined length exceeding 32 000 km; light rail systems add another 21 000 km of track across more than 220 cities.

China’s metro network extensions since 1990 have outpaced the global average, raising the country’s share of global metro networks from less than 10% in 1990 to more than 30% in 2017. Only three Chinese cities had metro services before 1990, compared with 33 in 2018.

New metro systems have opened in 46 cities since 2010, 34 of which are in Asia. In addition, new light rail transit systems have been launched in 65 cities – 28 in Europe, and the rest dispersed roughly equally among North America, Asia and the Middle East, and North Africa – for a total of 400 cities with light rail systems (some have both metro and light rail). The first light rail systems are also entering into operation in sub-Saharan Africa, in both Ethiopia and Nigeria.

The length of urban rail lines, which comprise both metro and light rail, has expanded 3.5% per year in the past decade, but even faster growth would help get on track with the SDS. Not only do urban rail systems help mitigate CO2 emissions and local air pollution, they also provide wider economic benefits to the cities they serve.

About 7% of global freight transport activity (measured in tonne kilometres) uses rail.

Transporting cargo by rail could be the least energy- and CO2-intensive way to move freight of any land-based transport mode, but as with passenger rail, its economic and environmental benefits depend upon the long-term certainty of high throughput volumes on certain routes.

Given that rising demand for rapid delivery of high-value and lighter goods has led to an ongoing shift from rail to road, it will be a challenge for rail to maintain its current share of freight transport. Nevertheless, by focusing investments on intermodal hubs and freight corridors where long-term certainty warrants them, supply chains can integrate rail to maximise its economic and environmental benefits.

Beyond CO2 emissions reduction potential, many benefits recommend rail as a choice mode of sustainable transport. 

  • In urban environments, rail is unparalleled in its throughput capacity (i.e. the potential to move large volumes of passengers). Its use can therefore reduce congestion, save valuable and scarce space, and generate wider economic benefits such as agglomeration effects. Urban rail is also far safer than road transport and better for local air quality.
  • High-speed rail is the only established low-carbon alternative to aviation for short-distance trips, and freight rail the only alternative to long-distance inland road freight transport. Aviation and long-haul road freight account for large, rapidly growing shares of transport-related energy demand and emissions, and alternative technology options are currently limited.

Exploiting rail potential fully will require supportive government policies and long-term investments, accompanied by strategic market-oriented business decisions by companies that build, operate and integrate rail with other transport modes. Consequently, there are opportunities for many stakeholders.

  • Rail project planners, operators and technology providers should focus on minimising costs and maximising revenues by increasing ridership and capturing land value, i.e. capitalising on the “aggregation” capacity of railway stations. For more on how both can be achieved, see The Future of Rail.
  • Governments must ensure that all transport modes pay for both infrastructure use and any adverse impacts, for example through road-pricing and congestion charges.

Conventional rail companies will need to upgrade their rolling stock and further electrify services, starting with the most heavily utilised routes. Introducing energy efficiency measures would both reduce environmental impacts and improve economic viability.

The adoption of digital technologies could optimise rail operations and integrate rail more comprehensively with other mobility services, making rail more accessible, convenient and attractive. Digital tools are therefore important for improving operational and energy efficiency, cutting costs and increasing revenues.

Monetising the commercial benefits of new rail is central to the economic viability of rail infrastructure projects, especially since average annual rail infrastructure investments will have to continue to grow for passenger rail to retain its current modal shares.

Rail operators should secure favourable terms for renewable electricity supplies so that electric rail can benefit the climate and local health as much as possible. In this way, some companies may be able to strengthen their environmental credentials and make their operations more sustainable.

Policy makers should adapt regulations to foster the competitiveness of rail.

A regulatory environment that prices transport according to the "user pays" and "polluter pays" principles is critical to provide economic equality for all modes of transport and to unlock to the significant sustainability benefits of rail.


The authors are grateful to Benjamin Welle, WRI, for reviewing and providing valuable feedback on a draft of this section.

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