Map of implemented/planned/possible routes for the Cape to Cairo railway. No differentiation between different segments (e.g. TAZARA railway, completed in 1970s only), but this would be possible. The link through Congo has never been finished, as far as I could find, but it is given in my main source - http://www.periodpaper.com/media/catalog/product/cache/1/image/8022f01105bea4edf676ba39d5976c14/T/W/TW3_327_8.JPG. Map source is File:Africa_1a.svg, with File:British Empire.png to select countries once part of the British Empire, here displayed in pink.
Own work
Classical geographer