Three mainline rail gauges in Australia were initiated in the very early years of railway development and remain in operation today. The diversity of track gauges – the distance between the inner rail edges – arose at a time when the respective colonies were building lines mainly to transport agricultural produce or minerals to ports. The colonies competed fiercely over trade with the United Kingdom and were quite isolationist in their attitude to each other.

During the 1850s, the local unavailability of anyone with knowledge of rail transport, including the relative advantages and disadvantages of particular gauges and the best track design, made decisions about the choice of gauge very difficult. Additionally, a change of mind by the colony of New South Wales as to the gauge of its first railway immediately conflicted with the projects already under way in South Australia and Victoria. The first of innumerable attempts to unify the gauges, often by engineers, occurred in 1857. However, politicians had little interest in standardising gauges; they applied unrelenting pressure to attain maximum development of railways at least possible construction cost.

When the Australian colonies federated in 1901 and trade barriers between the states were removed, the short-sightedness of having three gauges became very apparent. Even so, years of procrastination followed, in which the national and state legislatures put off the important decisions, engaging – usually after strong disagreement – in small projects only. In 1937, travel from Brisbane to Perth involved the discomfort of four railway systems, three gauges, and changes of train at eight stations. It would be 1995 before standard-gauge rails connected all the mainland state capitals – but regional routes remained largely unconverted. , there were of narrow gauge, of standard gauge, of broad gauge and of dual-gauge track: in all, Exclusive of sugar-cane lines.

Rail gauges and route kilometres

A report by the Australian Government’s Bureau of Infrastructure, Transport and Regional Economics, and the Australasian Railway Association, estimated that as of December 2024, there were of heavy rail lines open and operational throughout the nation.

The three main railway gauges in Australia are narrow: , standard: , and broad: . A slow progression towards unification to standard gauge has taken place since the 1930s.

About of light railways in Queensland support the sugar-cane industry. They are not included in the following table.

+Estimate of route kilometres of operational heavy railways in Australia, December 2024Excludes light rail (tram lines) and sugar cane lines. State or territory Narrow 1067mm Standard 1435mm Broad 1600mm Dual Total Australian Capital Territory7.57.5 New South Wales6,668.8736,741.8 Northern Territory1,6901,690 Queensland7,600.6117.137.17,754.7 South Australia662,605.8127.12,798.9 Tasmania614.4614.4 Victoria1,805.52,281.453.34,140.2 Western Australia2,642.14,649.7173.57,465.2 Total10,92317,544.32,481.5263.831,212.6

History

Pre-construction decisions In 1845, a Royal Commission on Railway Gauges in the United Kingdom was formed to report on the desirability for a uniform gauge. As a result, the Regulating the Gauge of Railways Act 1846 was passed which prescribed the use of in England, Scotland and Wales (with the exception of the Great Western Railway) and in Ireland.

In 1846, Australian newspapers discussed the break of gauge problem in the United Kingdom, especially for defence. In 1847, South Australia adopted the gauge as law.

In 1848, the Governor of New South Wales, Charles Fitzroy, was advised by the Secretary of State for the Colonies in London, Earl Grey, that one uniform gauge should be adopted in Australia, this being the British standard gauge. The recommendation was adopted by the then three colonies. Grey noted in his letter that South Australia had already adopted this gauge.

At this stage, South Australia was no longer part of NSW, while Victoria and Queensland were still part of New South Wales.

Since the Australian Overland Telegraph Line and under-sea cable communications with England did not open until 1872, communications between Britain and Australia before then were hampered by having to be conducted via sailing ship. The journey varied from about seven months on slower ships to about two and a half months on fast clipper ships. This had particular consequences for the selection of railway gauge in Australia.

Origins of the gauge muddle At that time, the private Sydney Railway Company had begun planning its railway line to Parramatta. The chief engineer of the company was Irish-born Francis Webb Sheilds. After his appointment in 1849, Sheilds initially stated a preference for but in 1850 he persuaded the company, which in turn asked the NSW legislature, to change to the Irish standard gauge of . This decision was endorsed by the NSW Governor, and Colonial Secretary Earl Grey in London agreed in 1851.

However, Sheilds and his three subordinates resigned in December 1850 when the company cut their salaries for financial reasons. After the interim appointment of Henry Mais in July 1852, the company selected a new Scottish engineer, James Wallace, who preferred the British standard gauge. The government was persuaded to make the change back to and in January 1853 they advised the company that the Act requiring would be repealed.

In February 1853, the other colonies (Victoria having separated from New South Wales in 1851) were sent a memorandum advising them of the pending change and recommended they likewise adopt . In Victoria, the memorandum was distributed to three railway companies and their responses were sought, with two replying and only one showing a distinct preference for . However, the Melbourne and Hobson's Bay Railway Company asked for a determination from the government as it had prepared plans for both gauges and was due to send an order for locomotives and rolling stock to England by boat at the start of April. In reply at the end of March, the companies were told the colonial Victorian government preferred and the order was subsequently placed.

In July 1853, the Government of Victoria advised New South Wales that it would use the broader gauge and later appealed to the British Government to force a reversal of New South Wales' decision. Subsequently, the Melbourne and Hobson's Bay Railway Company opened the first railway in Australia in 1854, as a broad gauge line, and the South Australian Railways used the same gauge on its first steam-hauled railway in 1856.

Despite a request by the Secretary of State for the Colonies to reconsider this alteration, in 1855, the NSW Governor William Denison gave the go-ahead for the Sydney to Parramatta railway, which opened in September of that year.

Concerns over the gauge difference began to be raised almost immediately. At a Select Committee called in Victoria in September 1853, a representative of the railway company which had not replied to Charles La Trobe's earlier memorandum, reported a preference for , but when asked if Victoria should follow NSW he answered: "We must, I conclude of necessity, do so". In 1857, the NSW railway engineer John Whitton suggested that the short length of railway then operating in New South Wales be altered from gauge to to conform with Victoria but, despite being supported by the NSW Railway Administration, he was ignored. At that time, there were only of track, four engines and assorted cars and wagons on the railway. However, by 1889, New South Wales, under engineer Whitton, had built almost 1,950 miles (3,500 km) of standard gauge line.

Extension of the gauge muddle The narrow gauge was introduced to Australia in 1865, when the Queensland Railways opened its first railway from Ipswich to Grandchester. The gauge was chosen on the supposition that it would be constructed more cheaply, faster and on tighter curves than the wider gauges. This was the first narrow gauge main line in the world.

South Australia first adopted this gauge in 1867 with its line from Port Wakefield to Hoyleton. The main reasons for choosing this were reduced cost, and the expectation that the narrow gauge would never connect to broad gauge lines. Overbuilt English railways were criticised. The Wakefield line was also envisaged as a horse-drawn tramway.

Later narrow gauge lines went towards Broken Hill and to Oodnadatta and from Mount Gambier. The Port Lincoln system was always isolated by geography which went through non-paying desert.

The Western Australian Government Railways adopted it in 1879 for its first line from Geraldton to Northampton.

The Tasmanian Government Railways opened its first railway from Launceston to Deloraine in 1871 using broad gauge, but converted to narrow gauge in 1888.

Towards a continental network Until the 1880s, the gauge issue was not a major problem, as there were no connections between the separate systems. The focus of railway traffic was movement from the hinterland to the ports and cities on the coast, so governments were not concerned about the future need for either inter-city passenger or freight services. It was not until 1883 when the broad and standard gauge lines from Melbourne and Sydney met at Albury, and in 1888, narrow and standard gauge from Brisbane and Sydney met at Wallangarra that the break of gauge became an issue.

The issue of rail gauge was mentioned in an 1889 military defence report authored by British army officer Major General James Bevan Edwards, who said that the full benefit of the railways would not be attained until a uniform gauge was established. Until the turn of the 20th century, the benefits of a uniform gauge were not immediately apparent, since passengers had to pass through customs and immigration at the intercolonial border, meaning that all goods would have to be removed for customs inspection. It was only with Federation in 1901 and its introduction of free trade between the states that the impediment of different gauges became apparent.

Post Federation At the time of Federation, standard gauge was used only in NSW, but was favoured for future construction. Work on gauge conversion was assisted by section 51 (xxxiii) of the Constitution of Australia, which made specific provisions for the Commonwealth Parliament to make laws with respect to railway acquisition and construction. An agreement was made with the South Australian and Western Australian state governments for the Trans-Australian Railway from Port Augusta to Kalgoorlie, with work started in 1911 and completed in 1917. However, with the different gauges, to transport goods from Queensland to Perth required four transhipments.

1921 royal commission In October 1921, a royal commission into uniform rail gauge recommended gauge conversion of large areas of the country and that: the gauge of 4feet 8inches be adopted as the standard no mechanical, third rail, or other device would meet the situation uniformity could be secured by one means only, viz., by conversion of the gauges other than 4ft 8 in. The subject was discussed at a conference of the Prime Minister with the Premiers in November 1921, when it was decided to adopt 4ft 8 in as the standard gauge for Australia and it was resolved that adoption of a uniform gauge was essential to the development and safety of the nation.

Following the royal commission, agreements were made for the standard gauge NSW North Coast line to be extended from Kyogle to South Brisbane (completed in 1930) and for the Trans-Australian Railway to be extended from Port Augusta to Port Pirie (completed 1937).

By the outbreak of World War II in 1939, there were still 14 break-of-gauge locations, with upwards of 1600 service personnel and many more civilians employed to transfer 1.8 million tons of freight during the conflict. The breaks of gauge were at the following places: