Distance, rather than topographical barriers or climatic hazards, has been the major constraint in developing and maintaining the transport system of South Australia. The River Murray and the 600 metre summit of the Mount Lofty Ranges have been the only significant physical obstacles to road and rail construction. The deep indentations of the gulfs have been, on balance, opportunities rather than constraints on the movement of goods. Although the South-East lacks a good seaport, most of the settled areas are close to coasts which have presented few difficulties for the development and maintenance of seaports.
The greater part of the railway system in South Australia is operated for the Commonwealth Government by the Australian National Railways Commission trading under the name Australian National (AN). In 1975, the State Government negotiated the sale of its country railways to the Commonwealth, the transfer taking effect from March 1978. Australian National operated 5547 route kilometres of track in South Australia in 1984. The State Transport Authority retains and operates 152 route kilometres of track in metropolitan Adelaide. Two private tramways are operated by Broken Hill Pty Co Ltd - 82 kilometres from Iron Knob and Iron Barron carrying iron ore, and 40 kilometres from Coffin Bay to Port Lincoln carrying limesand.
Human artifice produced awkward breaks in the State's rail system where none was required by nature. Three gauges - broad, narrow and standard - are legacies of political decisions taken between 1853 and 1913. The 1600 mm broad gauge was selected in the 1850s because it had been adopted by Victoria. In the 1870s the need for quick, cheap construction of routes to serve the new farming districts made the narrow 1067 mm gauge a popular choice. Finally, when the Commonwealth began construction of the transcontinental line between Port Augusta and Kalgoorlie in 1913, it adopted the standard, 1435 mm gauge used in New South Wales.
Standardisation of gauges has long been an objective of State and Commonwealth governments. The first section in South Australia to be rebuilt was from Port Augusta to Maree, serving the Leigh Creek coalfield; the second was from Port Pirie to Broken Hill, the third, from Crystal Brook to Adelaide, was completed in 1982, giving Adelaide unbroken rail connection with Perth, Alice Springs, Sydney and Brisbane. Apart from the isolated Eyre Peninsula section, the remaining sections of narrow-gauge track are virtually disused.
In the ninetieth century the prime function of the railways was to connect farmlands with the nearest ports; only gradually did the concept emerge of an integrated system serving predominantly long-distance and interstate freight. The map of principal rail freight flows for the year 1983-84 shows the importance of long-haul main-line traffic and the comparative insignificance of branch line flows. Branch line traffic consists mainly of seasonal grain and fertiliser deliveries, or high-bulk low-value commodities such as coal from Leigh Creek to Port Augusta, gypsum on the Penong to Thevenard line, steel products from Whyalla, and cement from the Barossa Valley. The predominant direction of flow is identified by large arrows where more than 80% of the freight moved in one direction, while the small arrows indicate where more than 65% moved in one direction. Branch-line freight flows are markedly one-directional, thus contributing to the relatively high operating costs. Main line, and especially interstate traffic, is more evenly balanced, although mineral ores from Broken Hill to Port Pirie and manufacture products and general merchandise bound for Western Australia and the Northern Territory make for a preponderance of west-bound flows on some routes. Non-metropolitan rail passenger services in South Australia with the exception of a reasonably well-patronised route to Mount Gambier, cater mainly for interstate travellers, especially on the overnight journey to and from Melbourne.
With nearly 4000 kilometres of coastline, South Australia has eighty-seven designated seaports and river ports, with all but five being government owned. Most of the minor ports no longer function as commercial ports, but their jetties and wharves are maintained for promenade and fishing purposes. There are eight State-owned commercial deep-sea ports and two coastal commercial ports, Kingscote and Klein Point. The five privately operated commercial deep-sea ports handle specialised bulk products at Port Stanvac (Petroleum Refineries Australia Pty Ltd), Ballast Head on Kangaroo Island (CSR Building Materials Division), and Ardrossan, Proper Bay and Whyalla (Broken Hill Pty Co Ltd). Since 1952 the intrastate pattern of grain shipments has changed from a large number of small coastal ports to the seven deep-sea ports where bulk handling facilities have been constructed.
The maps showing cargo handled at commercial seaports in 1983-84 reveal their contrasted functions in the State's trade patterns. Port Adelaide accounts for just over 21% of the total tonnage handled. It is the most diversified in the types of cargo handled, has the most even balance of exports and imports, and has the greatest range of physical facilities of any South Australian port. The inner harbour handles bagged and bulk grain, live sheep and imports of rock phosphate. The outer harbour with its modern container facilities handles most of the general merchandise and wool export trade, and most of the live sheep trade to the Middle East. Car carriers use facilities at both the outer and inner harbours. Port Stanvac, a private oil refinery port, imports mainly crude petroleum and exports refined products. With 20% of the State's total in gross tonnage, it ranks second to Port Adelaide. Whyalla, with 15% of the State's gross tonnage handled imports mainly coke from New South Wales and exports iron ore and metal products. The other ports in the State are markedly oriented to the export of bulk grain and non-metallic minerals such as gypsum.
The principal traffic flows by passenger services during November 1985 are shown on the maps. Buses have replaced rail services as the principal means of surface transport within the State, except between Adelaide and the South-East. The pattern of interstate bus services closely matches that of rail, with buses providing competitive services which are generally more frequent and faster. A passenger and vehicle service runs weekly from Port Adelaide to Port Lincoln, and twice weekly to Kangaroo Island, by the roll-on roll-off vessel MV Troubridge, commissioned in 1961. A recent development has been the provision of a number of short ferry connections by small craft from Cape Jervis across Backstairs Passage to Kangaroo Island.
Apart from a few international connections via Singapore and Auckland, air services based on Adelaide can be viewed as a three-level hierarchy. At the first level are the two airlines providing high-volume interstate connections. The second level operators provide regional services to Whyalla, Port Lincoln, Mount Gambier and Kangaroo Island. The third level or 'commuter' services range widely across the State and include services to Broken Hill, the Riverland, the smaller Eyre Peninsula centres, and the outback centres such as Leigh Creek, Olympic Dam and Coober Pedy.
As air transport services within South Australia are unregulated except for safety matters, several firms compete to provide light aircraft connections to country centres, and there are frequent changes in ownership.