A narrow-gauge railway is a railway with a track gauge narrower than standard 1,435 mm. Most narrow-gauge railways are between 600 mm and 1,067 mm.
In rail transport, track gauge or track gage is the spacing of the rails on a railway track and is measured between the inner faces of the load-bearing rails.
The War Department Light Railways were a system of narrow gauge trench railways run by the British War Department in World War I. Light railways made an important contribution to the Allied war effort in the First World War, and were used for the supply of ammunition and stores, the transport of troops and the evacuation of the wounded.
With railways, a break of gauge occurs where a line of one gauge meets a line of a different gauge. Trains and rolling stock cannot run through without some form of conversion between gauges, and freight and passengers must otherwise be transshipped. A break of gauge adds delays, cost, and inconvenience.
There were more than a thousand British narrow-gauge railways ranging from large, historically significant common carriers to small, short-lived industrial railways. Many notable events in British railway history happened on narrow-gauge railways including the first use of steam locomotives, the first public railway and the first preserved railway.
The Czech Republic formerly had a large number of narrow-gauge railways. Apart from the public lines listed below, there were many non-public industrial, forest and agricultural narrow-gauge systems; only a few of these are still running.
Rail transport in Australia involves a number of narrow-gauge railways. In some states they formed the core statewide network, but in the others they were either a few government branch lines, or privately owned and operated branch lines, often for mining, logging or industrial use.
Rail transport in Montenegro is operated by four separate companies, which independently handle railway infrastructure, passenger transport, cargo transport and maintenance of the rolling stock. The four companies were a part of public company Railways of Montenegro until it was split up in 2008.
Steam traction was the predominant form of motive power used by the Deutsche Reichsbahn on its narrow-gauge railways. For certain duties diesel locomotives were also used, albeit these were usually second-hand or rebuilt engines.
A number of private industrial railway lines were constructed in Greece for exclusive use by major mining operations and by extensive industrial facilities. There were also a few temporary lines, used for the construction of major public works. Most of them were either meter gauge or 600 mm narrow gauge.
Bosnian-gauge railways are railways with track gauge of 760 mm. These were found extensively in the former Austro-Hungarian Empire as a standardised form of narrow gauge. The name is also used for lines of the same gauge outside Bosnia, for example in Austria. Similar track gauges are the 2 ft 6 in and 750 mm gauge.
Most narrow-gauge railways in Italy were built with Italian metre gauge, which is actually 950 mm because historically the Italian track gauge was defined from the centres of the rail instead of the internationally accepted method of measuring the gauge from the inside edges of the rails. Several metre-gauge lines were built in northern Italy.
There are hundreds of kilometres of 600 mm, 750 mm, 785 mm, and 1,000 mm narrow-gauge lines in Poland. The metre-gauge lines are mostly found in the northwest part of the country in Pomerania, while 785 mm lines are found only in the Upper Silesia region. 750 mm is the most commonly used narrow gauge; it is used, for example, in the Rogów Narrow Gauge Railway and in Tarnowskie Góry with the world's oldest narrow-gauge railway in continuous service since 1853. Some narrow-gauge lines in Poland still operate as common carrier, while others survive as tourist attractions. One of the finest of the latter is the 600 mm narrow-gauge railway running from Żnin via Wenecja and famous Biskupin to Gąsawa in the Pałuki region. Railway traditions of Pałuki date back to July 1894 when the first two lines were opened.
Between 1917 and 1930 approximately 300 km of military and industrial narrow-gauge railways were built at the gauge of 600 mm and 750 mm or Bosnian gauge, built by Austria-Hungarians and Italians, intending to create a through route from Skopje and Tetovo to the Adriatic coast of Albania. None of these railways remained intact.
The vast majority of Finnish narrow-gauge railways were owned and operated by private companies. There are only a few instances where narrow-gauge railways were in direct connection with each other, and those interchanges did not last for long. The railways never formed a regional rail traffic network, but were only focused on maintaining connections between the national Russian-gauge railway network and the off-line industries.
The former Austria-Hungary empire had a narrow-gauge rail network thousands of kilometres in length, most of it using Bosnian gauge 760 mm or 600 mm gauge, constructed between 1870 and 1920. Landlords, mines, agricultural and forest estates established their own branch lines which, as they united into regional networks, increasingly played a role in regional passenger traffic. Following the Treaty of Trianon some railways were cut by the new border, many remained on the territory of Romania, Czechoslovakia and Yugoslavia. Due to a lack of intact roads, following World War II in many places narrow-gauge railway was the only reasonable way to get around. In 1968 the Communist government started to implement a policy to dismantle the narrow-gauge network in favour of road traffic. Freight haulage on the few remaining lines continued to decline until 1990 from when a patchwork of railways was gradually taken over by associations and forest managements for tourist purposes. State Railways operated narrow-gauge railways at Nyíregyháza and Kecskemét that played a role in regional transport until December 2009.
Europe inherited a diversity of rail gauges. Extensive narrow-gauge railway networks exist in Spain, Switzerland, Austria, Germany and Eastern Europe.
The Ohrid line was a narrow gauge railway line in what is now the Republic of North Macedonia. It ran to a gauge of 600 mm.
