standardgauge

Standard gauge, also known as Stephenson gauge, is a railway track gauge of 1,435 millimetres (4 feet 8 1/2 inches). It is the most widely used gauge for railways worldwide and serves as the de facto standard for much of the world’s rail infrastructure. The gauge originated in early 19th-century Britain; George Stephenson advocated 4 ft 8 1/2 in as a practical compromise, and the Liverpool and Manchester Railway, opened in 1830, used it. From Britain, the standard spread to continental Europe, the Americas, and parts of Asia as new lines were built or existing networks were converted.

Technical and interoperability considerations have reinforced its prominence. The 1,435 mm width provides a balance between stability, ride quality, and the ability to standardize rolling stock, loading gauges, and maintenance practices. It also supports cross-border operations and high-speed rail, aiding international freight and passenger services by allowing interchange of equipment and components across many countries.

Geographic distribution is broad but not universal. While standard gauge is dominant, several regions rely on other gauges, such as broad gauges of around 1,520 mm in parts of the former Soviet Union and India, and various narrow gauges, commonly around 1,000 mm or less, in other areas. Some countries operate multiple gauges or use gauge-changing technologies or dual-gauge tracks to accommodate different systems.

Converting to or integrating with standard gauge has been pursued in various national programs, sometimes through full gauge conversion, other times via dual-gauge or modular solutions to improve interoperability and facilitate international rail traffic.