Railways with a railway track gauge of 5 ft/1,524 mm were first constructed in the United Kingdom and the United States. This gauge is commonly called Russian gauge because this gauge was later chosen as the common track gauge for the Russian Empire. The gauge was redefined by Russian Railways to be 1520 mm, the primary region where Russian gauge is used is the former Soviet Union, Mongolia and Finland, with about 225,000 km of track. Russian gauge is the second most common gauge in the world, in 1748, the Wylam waggonway was built to a 5 ft gauge for the shipment of coal from Wylam to Lemington down the River Tyne. In 1839, the Eastern Counties Railway was constructed, and in 1840, in 1844, both lines were converted to 1,435 mm standard gauge. In 1903, the East Hill Cliff Railway, a funicular, was opened. In 1827, Horatio Allen, the engineer of the South Carolina Canal and Rail Road Company, prescribed the usage of 5 ft gauge. The presence of several distinct gauges was a disadvantage to the Confederate States of America during the American Civil War. In 1886, when around 11,500 miles of 5 ft gauge track existed in the United States, 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 which was built to 1,435 mm, for the building of Russias first major railway, the Moscow – Saint Petersburg Railway, engineer Pavel Melnikov hired as consultant George Washington Whistler, a prominent American railway engineer. Melnikov, of the Construction Commission overseeing the railway, recommended 6 ft 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 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 gauge. It is widely and incorrectly believed that Imperial Russia chose a gauge broader than standard gauge for military reasons, 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 forces. Finally for the Moscow - Saint Petersburg Railway, which became the benchmark, despite this the difference in gauge did play a role in hindering invading armies, especially in World War II, it was just not selected with that in mind. The 5-foot gauge became the standard in the whole Russian Empire and that includes the Baltic states, Ukraine, Belarus, the Caucasian and Central Asian republics, Finland, and in the once Soviet-influenced Mongolia. This formed a break of gauge between Changchun and Kuancheng, until the rest of the former Chinese Eastern Railway was converted to standard gauge, unlike in South Manchuria, the Soviet Unions 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 gauge simultaneously with the Russian gauge railway, constructed in the northern part of the island in 1930-1932
Image: Railroad of Confederacy 1861
Mixed between 1520 mm (Russian gauge) and another similar gauge, result the bonus gauge is 2140 mm (Brunel gauge).