High-speed rail

High-speed rail is a rail transport system where trains travel much faster than conventional ones, relying on specially designed trains and dedicated tracks. There is no single global standard, but lines built for at least 250 km/h (155 mph) or upgraded lines capable of 200 km/h (125 mph) are generally classified as high-speed. The first such system, the Tōkaidō Shinkansen, launched in Japan in 1964 on the island of Honshu. Its streamlined, spitzer-shaped nose earned it the English nickname "bullet train." Japan’s lead was soon followed by European nations—starting with Italy’s Direttissima line, then France, Germany, and Spain. Today, much of Europe has an extensive network with many international links. Since the 21st century, China has become the dominant player; by 2023, its high-speed network made up more than two-thirds of the global total. Many other countries and territories have also built high-speed rail to connect major cities, including Austria, Belgium, Denmark, Finland, Hong Kong (as part of China’s 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. However, only in continental Europe and Asia does high-speed rail cross international borders. Most high-speed trains run on standard-gauge tracks made of continuously welded rail, with grade-separated rights of way and large-radius curves. Some regions with wider legacy gauges—such as Russia and Uzbekistan—have developed high-speed lines using Russian gauge. No narrow-gauge high-speed railways exist. Countries like Japan and Spain, whose older networks use a different gauge than the standard 1,435 mm (56.5 in), have often built their high-speed lines to standard gauge instead. High-speed rail is the fastest and most efficient ground-based commercial transport. However, its construction is more expensive than conventional rail due to the need for large curves, gentle gradients, and grade-separated tracks, so it does not always offer an economic advantage. **Definitions**

Several definitions exist worldwide, with different international and regional bodies setting their own standards. Some countries also have their own legal definitions and technical criteria. **International Union of Railways (UIC) definition**

The UIC identifies three categories: - Category I: New tracks built for high speeds, with a maximum running speed of at least 250 km/h (155 mph). - Category II: Existing tracks upgraded for high speeds, with a maximum running speed of at least 200 km/h (124 mph). - Category III: Existing tracks upgraded for high speeds, with a maximum running speed of at least 200 km/h, but some sections have lower speed limits (e.g., due to topography or urban areas). A third definition for high-speed and very high-speed rail requires both: - Maximum achievable speed over 200 km/h (124 mph), or over 250 km/h (155 mph) for very high-speed. - Average running speed over the corridor above 150 km/h (93 mph), or above 200 km/h (124 mph) for very high-speed. The UIC prefers using "definitions" (plural) because no single standard exists, nor is there consistent use of terms like "high speed" or "very high speed." They reference the European EC Directive 96/48, which states that high speed combines all system elements: infrastructure, rolling stock, and operating conditions. The UIC emphasizes that high-speed rail is a set of unique features, not just a train exceeding a certain speed. Many conventionally hauled trains can reach 200 km/h in commercial service—such as France’s SNCF Intercités or Germany’s DB IC—but are not considered high-speed. The 200 km/h threshold is chosen for several reasons: above this speed, geometric defects have greater impact, track adhesion decreases, aerodynamic resistance rises sharply, pressure changes in tunnels cause passenger discomfort, and drivers struggle to read trackside signals. Standard signaling is often limited to speeds below 200 km/h—for example, 127 km/h (79 mph) in the US, 160 km/h (99 mph) in Germany, and 125 mph (201 km/h) in Britain. Above these limits, positive train control or the European Train Control System becomes necessary or legally required. **European Union definition**

EU Directive 96/48/EC, Annex 1 (see also Trans-European high-speed rail network) defines high-speed rail in terms of: - Infrastructure: Tracks built or upgraded specifically for high-speed travel. - Minimum speed: At least 250 km/h on specially built lines, and about 200 km/h on upgraded existing lines, applying to at least one section. Rolling stock must reach at least 200 km/h to qualify. - Operating conditions: Rolling stock must be designed together with its infrastructure for full compatibility, safety, and service quality.