Nearly all railways in South Africa use a 1,070 mm (3 ft 6 in) narrow gauge track (Cape gauge). This was selected in the 19th century to reduce the cost of building track across and through the mountains found in several parts of the country. The Gautrain rapid transit railway uses 1,435 mm (4 ft 8 1⁄2 in) (standard gauge). Ultimately, the hope is that the conversion to standard gauge will also enhance rail's potential as a freight carrier.
During the late 19th century and the early 20th century numerous 2-foot narrow gauge railways were constructed.
South African trains connect through the AAR coupler, developed in the United States at the end of the 19th century. Remarkably, though South Africa has long been ahead of Europe in coupling systems, it has lagged behind most of the world in its braking system; most trains in South Africa continue to use vacuum braking. However, the conversion toair brakes has finally commenced.
Between 50% to 80% of the rail lines in South Africa are electrified. Different voltages are used for different types of trains. Most electrified trains run 3000 V DC (overhead); this is used primarily for commuter lines, and has been in use since the 1920s. During the 1980s, higher voltages (25 kV AC and—much less frequently—50 kV AC (both overhead) have been used for heavy duty lines (also more sleepers per kilometre), primarily in the transport of iron ore.
