Railways with a track gauge of 5 ft 3 in (1,600 mm) fall within the category of broad gauge railways. As of 2022^[update], they were extant in Australia, Brazil and on the island of Ireland.

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600 BC

The Diolkos (Δίολκος) across the Isthmus of Corinth in Greece – a grooved paved trackway – was constructed with an average gauge of 5 ft 3 in (1,600 mm).^[1]

1840

The Grand Duchy of Baden State Railway was constructed in 1840-1851 to 5 ft 3 in (1,600 mm) gauge before being converted to 4 ft 8+1⁄2 in (1,435 mm) in 1854–1855.

1843

The Board of Trade of the United Kingdom of Great Britain and Ireland, after investigating a dispute caused by diverse gauges, recommended the use of 5 ft 3 in (1,600 mm) in Ireland.^[2]

1846

The Regulating the Gauge of Railways Act 1846 made 5 ft 3 in (1,600 mm) mandatory throughout all of Ireland.^[3][2]

1847

The Swiss Northern Railway was opened as a 5 ft 3 in (1,600 mm) line^[when?] and converted to 4 ft 8+1⁄2 in (1,435 mm) in 1854.

1854

The first Australian railway to operate steam-powered freight and passenger services, Melbourne and Hobson's Bay Railway Company, was built as a 5 ft 3 in (1600 mm) line.^[4]

1858

The first Brazilian 5 ft 3 in (1,600 mm) railway was opened: the Companhia de Estrada de Ferro Dom Pedro II.

1863

The Canterbury Railway in New Zealand was built in 5 ft 3 in (1,600 mm). It was converted to 3 ft 6 in (1,067 mm) in 1876.

• In Great Britain and Ireland, the gauge is known as Irish gauge.^[5][6][7] In Ireland it is also common to hear it referred to as "standard gauge" or "broad gauge" when distinguishing it from the various 3 ft (narrow gauge) railways of the island.^[8][9]
• In Australia, where the states of Victoria and South Australia have this gauge (as did Tasmania in the 19th century), it is also known as broad gauge.^{[10]: 168 [11]}
• In Brazil, the gauge is mainly known as broad gauge (Portuguese: bitola larga), but occasionally as Irish gauge (Portuguese: bitola irlandesa).^[12][13]

The Pennsylvania trolley gauges of 5 ft 2+1⁄2 in (1,588 mm) and 5 ft 2+1⁄4 in (1,581 mm) are similar to this gauge, but incompatible. There is also a 5 ft 2 in (1,575 mm) gauge. See: Track gauge in Ireland.

Before the advent of diesel and electric traction, one of the advantages of the broader 5 ft 3 in (1,600 mm) Irish gauge compared to 4 ft 8+1⁄2 in (1,435 mm) was that more space between steam locomotive frames allows for a bigger firebox, enabling generation of more steam.

• Track gauge in Australia