Keith, here's the portion of the "Narrow Gauge Railway" page in Wikipedia that pertains to Africa:
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Narrow gauge railways are common in Africa, where great distances, challenging terrain and low funding have made the narrow gauges attractive. Many nations, particularly in southern Africa, including the extensive South African Railway network (Spoornet), use a 3 ft 6 in (1,067 mm) gauge. Metre gauge is also common, as in the case of the Uganda Railway. There used to be extensive 2 ft (610 mm) and 600 mm (1 ft 11 5⁄8 in) gauge networks in countries such as Morocco, Congo, Angola, Namibia and South Africa, but these have mostly been dismantled or converted. Some also survives in Egypt.
Because Africa is divided into many countries, railways built by different governments tend not to link up with each other, each country's lines connecting its outlands with its own port. Incompatible gauges are therefore not obvious. For example, a link from Nigeria to Cameroon would join 3 ft 6 in (1,067 mm) to 1,000 mm (3 ft 3 3⁄8 in).
The railways of South Africa and many other African countries, including Angola, Botswana, Congo, Ghana, Mozambique, Namibia, Nigeria, Sudan, Zambia and Zimbabwe, use 1,067 mm (3 ft 6 in) gauge, sometimes referred to as Cape gauge. Kenya, Uganda and others use 1,000 mm (3 ft 3 3⁄8 in) gauge lines. In Tanzania former East African Railways lines are metre gauge while the TAZARA line is 3 ft 6 in (1,067 mm)
During the period of British colonisation of Africa, Cecil Rhodes advocated the construction of a Cape to Cairo railway, linking all British possessions along the eastern side of Africa between South Africa and Egypt. While most countries through which such a line would run have cape gauge lines, Tanzania and Kenya have metre gauge lines, although the TAZARA line in Tanzania is cape gauge.
