5 ft and 1520 mm gauge railways

In 1748, the Wylam waggonway was built to a 5 ft (1,524 mm) gauge for the shipment of coal from Wylam to Lemington down the River Tyne.[4]

In 1839, the Eastern Counties Railway was constructed. In 1840, the Northern and Eastern Railway was built. In 1844, both lines were converted to 1,435 mm (4 ft 8+1⁄2 in) standard gauge. In 1903, the East Hill Cliff Railway, a funicular, was opened.

5 ft (1,524 mm) gauge rail network in the Southern United States (1861)

In 1827, Horatio Allen, the chief engineer of the South Carolina Canal and Rail Road Company, prescribed the usage of 5 ft (1,524 mm) gauge. Many other railroads in the Southern United States adopted this gauge. The presence of several distinct gauges was a major disadvantage to the Confederate States of America during the American Civil War. In 1886, when around 11,500 miles (18,500 km) of 5 ft gauge track existed in the United States, almost all of the railroads using that gauge were converted to 4 ft 9 in (1,448 mm), the gauge then used by the Pennsylvania Railroad.[5]

In 1837, the first railway built in Russia was a 6 ft (1,829 mm) gauge, 17 km long experimental line connecting Saint Petersburg with Tsarskoye Selo and Pavlovsk. The choice of gauge was influenced by Brunel's Great Western Railway which used 7 ft (2,134 mm). The Tsarskoye Selo railway's success proved that a larger gauge could be viable for railways isolated from the extant 1,435 mm (4 ft 8+1⁄2 in) gauge Western European network.[6][7]

In 1840, work started on the second railway in the Russian Empire, the Warsaw–Vienna railway in Congress Poland. It was a 1,435 mm (4 ft 8+1⁄2 in) standard gauge, with the express intention of allowing through-freight trains into Austria-Hungary.[6][7]

The modern Russian railway network solidified around the Saint Petersburg–Moscow railway, built in 1842. There, the Tsar established a committee to recommend technical standards for the building of Russia's first major railway. The team included devotees of Franz Anton von Gerstner, who pushed to continue the Tsarskoye Selo gauge, and engineer Pavel Melnikov and his consultant George Washington Whistler, a prominent American railway engineer. Whistler recommended 5 ft (1,524 mm) on the basis that it was cheaper to construct than 6 ft (1,829 mm) and cheaper to maintain than 1,435 mm (4 ft 8+1⁄2 in). His advice won over the Tsar.[6][7]

At the time, questions of continuity with the European network did not arise. By the time difficulties arose in connecting the Prussian railroads to the Russian ones in Warsaw in the 1850s, it was too late to change.[6]

A persistent myth holds that Imperial Russia chose a gauge broader than standard gauge for military reasons, namely to prevent potential invaders from using the rail system.[8] The Russian military recognized as early as 1841 that operations to disrupt railway track did not depend on the gauge, and should instead focus on destroying bridges and tunnels.[6][7]

The 5-foot gauge became the standard in the Russian Empire and later the Soviet Union.

Russian engineers used it on the Chinese Eastern Railway, built in the closing years of the 19th century across the Northeastern China entry to provide a shortcut for the Trans-Siberian Railway to Vladivostok. The railway's southern branch, from Harbin via Changchun to Lüshun, used Russian gauge. As a result of the Russo-Japanese War of 1904-1905, its southernmost section from Changchun to Lüshun was lost to the Japanese, who promptly regauged it to standard gauge, after using the narrow 3 ft 6 in (1,067 mm) for a short time during the war.[9] This formed a break of gauge between Changchun and Kuancheng, the station just to the north of Changchun, still in Russian hands,[10] until the rest of the former Chinese Eastern Railway was converted to standard gauge, probably in the 1930s.

Unlike in South Manchuria, the Soviet Union's reconquest of southern Sakhalin from Japan did not result in regauging of the railway system. Southern Sakhalin has continued with the original Japanese 1,067 mm (3 ft 6 in) gauge simultaneously with the Russian gauge railway, constructed in the northern part of the island in 1930-1932 (Moskalvo-Okha). The railway has no fixed connection with the mainland. Before 2019, rail cars coming from the mainland port of Vanino on the Vanino-Kholmsk train ferry, operating since 1973, had to have their bogies changed in the Sakhalin port of Kholmsk.[11] In 2004 and 2008 plans were put forward to convert it to the Russian gauge. The conversion was completed in 2019.[12]

There were proposals in 2013 for north-south and east-west lines in Afghanistan, with construction to start in 2013.[13]

The Panama Canal Railway, first constructed in ca. 1850, was built in 5 ft (1,524 mm) gauge. During canal construction (1904–1914), this same gauge was chosen for both construction traffic, canal operating services along the quays, and the newly routed commercial cross-isthmus railway. In 2000 the gauge for the commercial parallel railway was changed to 1,435 mm (4 ft 8+1⁄2 in) to use standard gauge equipment. The original gauge was chosen under the influence of the pre-conversion southern United States railway companies. The electric manoeuvering locomotives along the locks (mules) still use the 5 ft gauge that was laid during canal construction.

The first rail line in Finland was opened in January 1862. As Finland was then the Grand Duchy of Finland, an autonomous state within the Imperial Russia where railways were built to the (5 ft) broad track gauge of 1,524 mm (5 ft).[14] The railway systems were not connected until the bridge over the River Neva was built in 1913.[15] Russian trains could not have run on Finnish tracks, because the Finnish loading gauge was narrower, until the connection was made and the Finnish structure gauge was widened.

In the late 1960s the gauge was redefined to 1,520 mm (4 ft 11+27⁄32 in) in the Soviet Union.[3] At the same time the tolerances were tightened. As the running gear (wheelsets) of the rolling stock remained unaltered, the result was an increased speed and stability.[14] The conversion took place between 1970 and the beginning of the 1990s.[14]

In Finland, the Finnish State Railways kept the original definition of 1,524 mm (5 ft), even though they also have tightened the tolerances in a similar way, but to a higher level.

After its independence from the Soviet Union in 1991, Estonia redefined its track gauge to 1,524 mm, to match Finland's gauge.[16] The redefinition did not mean that all the railways in Estonia were changed immediately. It was more a rule change, so that all renovated old tracks and new railways would be constructed in 1,524 mm gauge from then on. (See Track gauge in Estonia.)

Finland allows its gauge to be 1,520–1,529 mm on first class lines (classes 1AA and 1A, speed 220–160 km/h).[17]

If the gauge of the rolling stock is kept within certain limits, through running between 1,520 mm (4 ft 11+27⁄32 in) railways and Finnish 1,524 mm (5 ft) railways is allowed. Since both 1,520 and 1,524 mm are within tolerances, the difference is tolerable.

The gauge of the international high-speed train Allegro (Sm6) between Helsinki and St. Petersburg was specified as 1,522 mm.[18]

The loading gauge, which defines the maximum height and width for railway vehicles and their loads, is larger for Russian gauge. This means that if a standard gauge railway, in Europe, is adapted for dual gauge, bridges must be rebuilt, double tracks must be placed further apart and the overhead wire must be raised. Or there must be restrictions on permitted rolling stock, which would restrict the benefit of such a railway. Dual gauge needs more width than single gauge. For double stacking on Russian gauge tracks, maximum height shall be 6.15 or 6.4 m (20 ft 2 in or 21 ft 0 in) above rails.

For standard gauge railways, double stacking maximum height shall be 6.15 m (20 ft 2 in). For Indian gauge railways, double stacking maximum height shall be 7.1 m (23 ft 4 in), and minimum overhead wiring height shall be 6.5 or 6.75 m (21 ft 4 in or 22 ft 2 in) above rails. Minimum overhead wiring height for double stacking, standard gauge railways shall be 6.5 m (21 ft 4 in), and Indian gauge railways shall be 7.45 m (24 ft 5 in) above rails, respectively. This would apply to Russia and Europe (or North America), rather than to Russia and China (or Iran).

The primary countries currently using the gauge of 5 ft or 1,520 mm, include:[19]

Short sections of Russian or 5 ft gauge extend into Poland, eastern Slovakia, Sweden (at the Finnish border at Haparanda), and northern Afghanistan.[20]

There is an approximately 150 km long section in Hungary in the Záhony logistics area close to the Ukrainian border.[21]

Following renovations in 2014, a 32 km section of dual Standard/Russian gauge was installed between Tumangang and Rajin stations in North Korea.[22]

The most western 1,520 mm gauge railway is the Polish LHS (Linia Hutnicza Szerokotorowa) from the Ukrainian border to the eastern end of the Silesian conurbation.

Although broad gauge is quite rare on lighter railways and street tramways worldwide, almost all tramways in the former USSR are broad gauge (according to terminology in use in these countries, gauges narrower than 1,520 mm (4 ft 11+27⁄32 in) are considered to be narrow). Many tramway networks initially built to narrow gauges (750 mm or 2 ft 5+1⁄2 in or 1,000 mm or 3 ft 3+3⁄8 in metre gauge) were converted to broad gauge. As of 2015, only a few out of more than sixty tram systems in Russia are not broad gauge: 1,000 mm in Kaliningrad and Pyatigorsk, 1,435 mm (4 ft 8+1⁄2 in) in Rostov-on-Don. There are two tram systems in and around Yevpatoria that use 1,000 mm (3 ft 3+3⁄8 in) gauge.[note 1]

Finland's Helsinki trams and Latvia's Liepāja trams use 1,000 mm (3 ft 3+3⁄8 in). Estonia's Tallinn trams use similar 1,067 mm (3 ft 6 in). Warsaw's tramway system, constructed with 1525 mm gauge, was regauged to 1435 mm during post-WWII reconstruction.[23] Tampere tramway, built in 2021, uses 1,435 mm (4 ft 8+1⁄2 in).

Underground urban rapid transit systems in the former USSR, like the Moscow Metro, Saint Petersburg Metro, Kyiv Metro and Yerevan Metro use Russian gauge (1,520 mm). Outside the former USSR, the Helsinki Metro in Finland that utilizes a unique track gauge of 1,522 mm, falls between the Russian gauge (1,520 mm) and broad gauge 1,524 mm.