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; and 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 and many other railroads in 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]

The first railway built in Russia was built in 1837 to 6 ft (1,829 mm) gauge for a 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). While of almost no practical importance the railway did demonstrate that this gauge was viable. The second railway in the Russian Empire was the Warsaw–Vienna railway (Congress Poland was then a part of the Empire) which was built to 1,435 mm (4 ft 8 ¹⁄₂ in) and commenced construction in 1840.

For the building of Russia's first major railway, the Moscow – Saint Petersburg Railway, engineer Pavel Melnikov hired as 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) while still offering the same advantages over 1,435 mm (4 ft 8 ¹⁄₂ in) and that there was no need to worry about a break-of-gauge since it would never be connected to the Western European railways. Colonel P.P. Melnikov, of the Construction Commission overseeing the railway, recommended 6 ft (1,829 mm) following the example of the first railway and his study of US Railways. Following a report sent by Whistler the head of the Main Administration of Transport and Buildings recommended 5 ft (1,524 mm) and it was approved for the railway by Tsar Nicholas I on February 14, 1843. The next lines built were also approved with this gauge but it was not until March 1860 that a Government decree stated all major railways in Russia would be 5 ft (1,524 mm) gauge.

It is widely and incorrectly believed that Imperial Russia chose a gauge broader than standard gauge for military reasons, namely to prevent potential invaders from using the rail system. In 1841 a Russian army engineer wrote a paper stating that such a danger did not exist since railways could be made dysfunctional by retreating or diverting forces. Also the construction of the Warsaw–Vienna railway in 1,435 mm (4 ft 8 ¹⁄₂ in) was precisely so it could be connected to the Western European network, in that case to reduce Poland's dependence on Prussia for transport. Finally for the Moscow – Saint Petersburg Railway, which became the benchmark, the choice of track gauge was between 5 ft (1,524 mm) and the wider 6 ft (1,829 mm), not standard gauge 1,435 mm (4 ft 8 ¹⁄₂ in).[6] However, it was just not selected with that in mind. When a railway has wooden sleepers, it is fairly easy to make the gauge narrower by removing the nails and placing them back at a narrower position, something Germany did during WWII. Destroying river bridges had a larger effect.

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

Russian engineers used it also 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 Transsiberian Railway to Vladivostok. The railway's southern branch, from Harbin via Changchun to Lüshun, used the Russian gauge, but 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).[7] This formed a break of gauge between Changchun and Kuancheng (the station just to the north of Changchun, still in Russian hands),[8] until the rest of the former Chinese Eastern Railway was converted to standard gauge, too (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, and rail cars coming from the mainland port of Vanino on the Vanino-Kholmsk train ferry (operating since 1973) have their bogies changed in the Sakhalin port of Kholmsk.[9] In 2004 and 2008 plans were put forward to convert it to Russian gauge. The estimated completion date now is 2020.[10]

There were proposals in 2013 for north-south and east-west lines in Afghanistan, with construction to commence in 2013.[11]

The Panama 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. Nowadays, 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 on January 31, 1862. As Finland was then the Grand Duchy of Finland; a region of Imperial Russia, railways were built to the then Russian track gauge of 5 ft (1,524 mm),[12] although the railway systems were not connected until the bridge over River Neva was built in 1913.[13] Russian trains could not have run in the Finnish tracks, because the Finnish loading gauge was narrower until the connection was made, and the Finnish structure gauge was widened.

Currently, there are two passenger services between Finland and Russia: Allegro, a Pendolino service on the Helsinki–St. Petersburg route, which crosses the border at Vainikkala, and Tolstoi, an overnight daily service between Helsinki and Moscow. For cargo traffic, there are four border crossings in active use.[14]

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.[12] The conversion took place between 1970 and the beginning of the 1990s.[12]

In Finland 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. (Tolerance tighter than in the Soviet Union)

The other Finnic nation Estonia redefined its track gauge also to 1,524 mm to match with Finland's gauge after the end of Soviet occupation and annexation in 1991.[15] 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 construed in 1524mm 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).[16]

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. However, certain Finnish rolling stock do have a tendency to get stuck in Russian railyards due to too narrow gauge.

The international high-speed train Allegro (Sm6) between Helsinki and St. Petersburg is specified as 1,522 mm gauge.[17] High-speed trains have less tolerance against gauge error, but this way through running works well.

The loading gauge, that permits the height and width of trains, is larger for Russian gauge. This means that if a standard gauge railway shall be 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 the Russian gauge tracks, maximum height shall be 6.15m or 6.4m above rails,[18] and minimum overhead wiring height shall be 6.5m or 6.75m above rails,[19] respectively. This would apply to Russia and Europe (or North America), rather than to Russia and China (or Iran).

Short sections of Russian 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] During the recent renovation a 32 km section of dual Standard/Russian gauge was installed between Tumangang and Rajin stations in the DPRK.[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 ex-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 also two tram systems in and around Yevpatoria[23] that use 1,000 mm (3 ft 3 ³⁄₈ in) gauge. Finland's Helsinki trams and Latvia's Liepāja trams also use 1,000 mm (3 ft 3 ³⁄₈ in), and 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.[24]

Underground urban rapid transit systems in former USSR and Finland, like the Moscow Metro, Saint Petersburg Metro, Kyiv Metro and the Helsinki Metro use Russian gauge (1,520 mm) or 1,524 mm gauge.

That is 5 ft (1,524 mm).

That is 1,520 mm (4 ft 11 ²⁷⁄₃₂ in).