IEA (2019), "Tracking Transport", IEA, Paris https://www.iea.org/reports/tracking-transport-2019
While the share of rail passenger-km travelled has been a steady 8% since 2000 despite rapid rail infrastructure expansion, rail operations account for only 2% of transport sector energy use.
Rail services consume less than 0.6 million barrels per day of oil (about 0.6% of global oil use), around 290 terawatt hours (TWh) of electricity (more than 1% of global consumption) and are responsible for 0.3% of direct CO2 emissions.
The low energy and CO2 intensities of rail transport make promoting rail a promising strategy to diversify energy sources and reduce emissions. Shifting passenger and freight services from more intensive modes such as cars, trucks and airplanes would substantially reduce net energy use and emissions and make the Sustainable Development Scenario (SDS) more 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 rail construction 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.
Urban rail is ideally suited to high passenger throughput, and although per-kilometre capital costs are high, costs per throughput capacity are lower than for urban road infrastructure.
Rail infrastructure investment increased nearly threefold between 2005 and 2015, with most of this growth in China (OECD, 2018), whose share within a group of more than 40 countries has grown from less than 20% to more than half in the past decade.
Urban and high-speed rail infrastructure have 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 and high-speed rail networks are electric, and electrification of conventional rail is expected to continue at a rapid pace.
Rail services can be broadly grouped into passenger and freight. Passenger rail can then be classified based on operational characteristics.
- Urban (including light rail and metro)
- Conventional (including suburban and intercity)
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 8% 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.
Today, around 600 billion passenger-km are travelled by high-speed rail every year, compared with 3 100 billion passenger-km by conventional rail.
More than two out of three high-speed rail tracks are in China: starting from virtually none only a decade ago, the country now has over 41 000 km. The rapidity and magnitude of this achievement make it one of the largest infrastructure projects of recent history, and total high-speed rail activity in China is catching up with passenger aviation.
Owing largely to China’s commitment to high-speed rail, 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 can 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.
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 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 to 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 has the potential to provide 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.
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.
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.
In this way, some companies may be able to strengthen their environmental credentials and make their operations more sustainable.
A regulatory environment that prices transport according to the "user pays" and "polluter pays" principles is critical to provide a level economic playing field across modes of transport, and to unlocking to the significant sustainability benefits of rail.
Expanding high-quality urban rail transport depends on political champions, thorough project viability and costs assessments and effective funding, as much as it does on technical issues. Equally important are sound construction, installation of the necessary equipment and hardware, and well-managed operations.
Digital technologies can be used to help integrate rail with other transport modes, provide superior service and increase utilisation to raise revenues and reduce costs.
By reducing the time and distance between trains, digital technologies can facilitate more intensive use of rail infrastructure, which increases capacity and boosts investment returns while improving user convenience and maintaining high safety standards.
A rich literature finds that the provision of reliable, convenient, and affordable public transit, and in the case of large cities, metro and light rail, not only reduces the per capita transport emissions in these cities, but can also contribute substantially to reducing levels of pollutants associated with road vehicles, and also enables reductions in the macro- and micro-economic costs of providing urban mobility.
Other studies identify economic and equity benefits that come from urban rail systems.
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Many thanks to Laurent Dauby of the UITP for providing valuable input and feedback on this section.