High-speed rail (HSR) is a type of rail transport network utilizing trains that run significantly faster than those of traditional rail, using an integrated system of specialized rolling stock and dedicated tracks. While there is no single definition or standard that applies worldwide, lines built to handle speeds of at least or upgraded lines of at least are generally considered to be high-speed.
The first high-speed rail system, the Tōkaidō Shinkansen, began operations in Honshu, Japan, in 1964. Due to the streamlined spitzer-shaped nose cone of the trains, the system also became known by its English nickname bullet train. Japan's example was followed by several European countries, initially in Italy with the Direttissima line, followed shortly thereafter by France, Germany, and Spain. Today, much of Europe has an extensive network with numerous international connections. Construction since the 21st century has led to China taking a leading role in high-speed rail. , China's HSR network accounted for over two-thirds of the world's total.
In addition to these, many other countries/territories have developed high-speed rail infrastructure to connect major cities, including: Austria, Belgium, Denmark, Finland, Hong Kong (part of Chinese network), Indonesia, Morocco, the Netherlands, Norway, Poland, Portugal, Russia, Saudi Arabia, Serbia, South Korea, Sweden, Switzerland, Taiwan, Turkey, the United Kingdom, the United States, and Uzbekistan. Only in continental Europe and Asia does high-speed rail cross international borders.
High-speed trains mostly operate on standard gauge tracks of continuously welded rail on grade-separated rights of way with large radii. However, certain regions with wider legacy railways, including Russia and Uzbekistan, have sought to develop a high-speed railway network in Russian gauge. There are no narrow gauge high-speed railways. Countries whose legacy network is entirely or mostly of a different gauge than – including Japan and Spain – have often opted to build their high speed lines to standard gauge instead of the legacy railway gauge.
High-speed rail is the fastest and most efficient ground-based method of commercial transport. Due to requirements for large track curves, gentle gradients and grade separated track the construction of high-speed rail is costlier than conventional rail and therefore does not always present an economical advantage over conventional rail.
Definitions
Multiple definitions for high-speed rail are in use worldwide, with various international organisations and regional bodies establishing different standards. Several countries have also developed their own legal definitions and technical standards for high-speed rail.
International Union of Railways definition The International Union of Railways (UIC) identifies three categories of high-speed rail:
Category I: New tracks specially constructed for high speeds, allowing a maximum running speed of at least 250 km/h (155 mph). Category II: Existing tracks specially upgraded for high speeds, allowing a maximum running speed of at least 200 km/h (124 mph). Category III: Existing tracks specially upgraded for high speeds, allowing a maximum running speed of at least 200 km/h, but with some sections having a lower allowable speed (for example due to topographic constraints, or passage through urban areas).
A third definition of high-speed and very high-speed rail requires simultaneous fulfilment of the following two conditions: Maximum achievable running speed in excess of , or for very high-speed, Average running speed across the corridor in excess of , or for very high-speed.
The International Union of Railways prefers to use "definitions" (plural) because they consider that there is no single standard definition of high-speed rail, nor even standard usage of the terms ("high speed", or "very high speed"). They make use of the European EC Directive 96/48, stating that high speed is a combination of all the elements which constitute the system: infrastructure, rolling stock and operating conditions. The International Union of Railways states that high-speed rail is a set of unique features, not merely a train travelling above a particular speed. Many conventionally hauled trains are able to reach in commercial service but are not considered to be high-speed trains. These include the French SNCF Intercités and German DB IC.
The criterion of is selected for several reasons; above this speed, the impacts of geometric defects are intensified, track adhesion is decreased, aerodynamic resistance is greatly increased, pressure fluctuations within tunnels cause passenger discomfort, and it becomes difficult for drivers to identify trackside signalling. Standard signaling equipment is often limited to speeds below , with the traditional limits of in the US, in Germany and in Britain. Above those speeds positive train control or the European Train Control System becomes necessary or legally mandatory.
European Union definition The European Union Directive 96/48/EC, Annex 1 (see also Trans-European high-speed rail network) defines high-speed rail in terms of:
Infrastructure: Track built specially for high-speed travel or specially upgraded for high-speed travel. Minimum speed limit: Minimum speed of on lines specially built for high speed and of about on existing lines which have been specially upgraded. This must apply to at least one section of the line. Rolling stock must be able to reach a speed of at least 200 km/h to be considered high speed. Operating conditions: Rolling stock must be designed alongside its infrastructure for complete compatibility, safety and quality of service.
National legal definitions Some national legal definitions of high-speed rail include:
Australia According to the High Speed Rail Authority Act 2022, high-speed rail in Australia is defined as a railway capable of supporting trains that can travel at speeds exceeding 250 km/h. As of 2026, Australia has one planned railway which would meet their definition.
China According to China's Ministry of Railways Order No. 34 (2013), high-speed rail refers to new passenger rail lines designed to operate at speeds of 250 km/h or higher, with initial service running at least 200 km/h.
Japan The first law defining high-speed rail was Japan's "", Act No. 71 of May 18, 1970.
Article 2 of this law provided the following definition: "An artery railway that is capable of operating at the speed of 200km/h or more in its predominating section."
This law formalised the definition of high-speed railways in Japan and established a framework for the Shinkansen network, which had started operation in 1964.
South Korea South Korea defines high-speed rail through the Railway Service Act (2004), which categorises railway lines and trains into three types:
High-speed railway lines: Can run at speeds of 300 km/h or more on the majority of tracks. Semi-high-speed railway lines: Can run at speeds between 200 km/h to 300 km/h on the majority of tracks. Conventional lines: Can run at a maximum speed of less than 200 km/h on the majority of tracks.
The Act also categorises trains into corresponding types based on their maximum speeds.
United States United States federal law defines high-speed rail as intercity passenger rail service expected to reach speeds of at least .
History Railways were the first form of rapid land transport and had an effective monopoly on long-distance passenger traffic until the development of the motor car and airliners in the early to mid-20th century. Speed had always been an important factor for railways and they constantly tried to achieve higher speeds and decrease journey times. Rail transport in the late 19th century was not much slower than non-high-speed trains today, and many railways regularly operated relatively fast express trains which averaged speeds of around .Official Guide of the Railways, 1910: The Official Guide of the Railways and Steam Navigation Lines of the United States, Puerto Rico, Canada, Mexico, and Cuba, Rand McNally & Company Publishing, 1910,
Early research
First experiments High-speed rail development began in Germany in 1899 when the Prussian state railway joined with ten electrical and engineering firms and electrified of military-owned railway between Marienfelde and Zossen. The line used three-phase current at 10 kilovolts and 45 Hz.
The Van der Zypen & Charlier company of Deutz, Cologne built two railcars, one fitted with electrical equipment from Siemens-Halske, the second with equipment from Allgemeine Elektricitäts-Gesellschaft (AEG), that were tested on the Marienfelde–Zossen line during 1902 and 1903 (see Experimental three-phase railcar).
On 23 October 1903, the S&H-equipped railcar achieved a speed of and on 27 October the AEG-equipped railcar achieved .Sith Sastrasinh, "Electrical Train Marienfelde–Zossen in 1901 ", 21 January 2000, WorldRailFans. Accessed 23 January 2013. These trains demonstrated the feasibility of electric high-speed rail; however, regularly scheduled electric high-speed rail travel was still more than 30 years away.
High-speed aspirations After the breakthrough of electric railroads, it was clearly the infrastructure – especially the cost of it – which hampered the introduction of high-speed rail. Several disasters happened – derailments, head-on collisions on single-track lines, collisions with road traffic at grade crossings, etc. The physical laws were well-known, i.e. if the speed was doubled, the curve radius should be quadrupled; the same was true for the acceleration and braking distances.
In 1891, engineer Károly Zipernowsky proposed a high-speed line from Vienna to Budapest for electric railcars at . In 1893 Wellington Adams proposed an air-line from Chicago to St. Louis of , at a speed of only .
Alexander C. Miller had greater ambitions. In 1906, he launched the Chicago-New York Electric Air Line Railroad project to reduce the running time between the two big cities to ten hours by using electric locomotives. After seven years of effort, less than of straight track was finished. A part of the line is still used as one of the last interurbans in the US, the South Shore Line.
High-speed interurbans In the US, some of the interurbans (i.e. trams or streetcars which run from city to city) of the early 20th century were very high-speed for their time (also Europe had and still does have some interurbans). Several high-speed rail technologies have their origin in the interurban field.
In 1903 – 30 years before the conventional railways started to streamline their trains – the officials of the Louisiana Purchase Exposition organised the Electric Railway Test Commission to conduct a series of tests to develop a carbody design that would reduce wind resistance at high speeds. A long series of tests was carried. In 1905, St. Louis Car Company built a railcar for the traction magnate Henry E. Huntington, capable of speeds approaching . Once it ran between Los Angeles and Long Beach in 15 minutes, an average speed of . However, it was too heavy for much of the tracks, so Cincinnati Car Company, J. G. Brill and others pioneered lightweight constructions, use of aluminium alloys, and low-level bogies which could operate smoothly at extremely high speeds on rough interurban tracks. Westinghouse and General Electric designed motors compact enough to be mounted on the bogies. From 1930 on, the Red Devils from Cincinnati Car Company and some other interurban rail cars reached about in commercial traffic. The Red Devils weighed only 22 tons though they could seat 44 passengers.