Narrow-gauge railway

A narrow-gauge railway (narrow-gauge railroad in the US) is a railway with a track gauge (distance between the rails) narrower than 1,435 mm (4 ft 8+1⁄2 in) standard gauge. Most narrow-gauge railways are between 600 mm (1 ft 11+5⁄8 in) and 1,067 mm (3 ft 6 in).

Since narrow-gauge railways are usually built with tighter curves, smaller structure gauges, and lighter rails, they can be less costly to build, equip, and operate than standard- or broad-gauge railways (particularly in mountainous or difficult terrain). Lower-cost narrow-gauge railways are often used in mountainous terrain, where engineering savings can be substantial. Lower-cost narrow-gauge railways are often built to serve industries as well as sparsely populated communities where the traffic potential would not justify the cost of a standard- or broad-gauge line. Narrow-gauge railways have specialised use in mines and other environments where a small structure gauge necessitates a small loading gauge.

In some countries, narrow gauge is the standard: Japan, Indonesia, Taiwan, New Zealand, South Africa, and the Australian states of Queensland, Western Australia and Tasmania have a 3 ft 6 in (1,067 mm) gauge, whereas Vietnam, Malaysia and Thailand have metre-gauge railways. Narrow-gauge trams, particularly metre-gauge, are common in Europe. Non-industrial, narrow-gauge mountain railways are (or were) common in the Rocky Mountains of the United States and the Pacific Cordillera of Canada, Mexico, Switzerland, Bulgaria, the former Yugoslavia, Greece, and Costa Rica.

A narrow-gauge railway is one where the distance between the inside edges of the rails is less than 1,435 mm (4 ft 8+1⁄2 in). Historically, the term was sometimes used to refer to what are now standard-gauge railways, to distinguish them from broad-gauge railways, but this use no longer applies.

The earliest recorded railway appears in Georgius Agricola's 1556 De re metallica, which shows a mine in Bohemia with a railway of about 2 ft (610 mm) gauge. During the 16th century, railways were primarily restricted to hand-pushed, narrow-gauge lines in mines throughout Europe. In the 17th century, mine railways were extended to provide transportation above ground. These lines were industrial, connecting mines with nearby transportation points (usually canals or other waterways). These railways were usually built to the same narrow gauge as the mine railways from which they developed.

The world's first steam locomotive, built in 1802 by Richard Trevithick for the Coalbrookdale Company, ran on a 3 ft (914 mm) plateway. The first commercially successful steam locomotive was Matthew Murray's Salamanca built in 1812 for the 4 ft 1 in (1,245 mm) Middleton Railway in Leeds. Salamanca was also the first rack-and-pinion locomotive. During the 1820s and 1830s, a number of industrial narrow-gauge railways in the United Kingdom used steam locomotives. In 1842, the first narrow-gauge steam locomotive outside the UK was built for the 1,100 mm (3 ft 7+5⁄16 in)-gauge Antwerp-Ghent Railway in Belgium. The first use of steam locomotives on a public, passenger-carrying narrow-gauge railway was in 1865, when the Ffestiniog Railway introduced passenger service after receiving its first locomotives two years earlier.

Many narrow-gauge railways were part of industrial enterprises and served primarily as industrial railways, rather than general carriers. Common uses for these industrial narrow-gauge railways included mining, logging, construction, tunnelling, quarrying, and conveying agricultural products. Extensive narrow-gauge networks were constructed in many parts of the world; 19th-century mountain logging operations often used narrow-gauge railways to transport logs from mill to market. Significant sugarcane railways still operate in Cuba, Fiji, Java, the Philippines, and Queensland, and narrow-gauge railway equipment remains in common use for building tunnels.

In 1897, a manganese mine in the Lahn valley in Germany was using two benzine-fueled locomotives with single cylinder internal combustion engines on the 500mm gauge tracks of their mine railway; these locomotives were made by the Deutz Gas Engine Company (Gasmotorenfabrik Deutz), now Deutz AG. Another early use of internal combustion was to power a narrow-gauge locomotive was in 1902. F. C. Blake built a 7 hp petrol locomotive for the Richmond Main Sewerage Board sewage plant at Mortlake. This 2 ft 9 in (838 mm) gauge locomotive was probably the third petrol-engined locomotive built.