I have an idea that the train journey in the song refers to the journey of poor rural people to the mines of Johannesberg - a journey to great hardship but also providing the means to feed their families. I've heard it in South Africa with "South Africa" instead of "Zimbabwe". I guess the song is common to many southern African countries who insert the name of their own country into the lyrics.

The word "shoshaloza" is onomatopoeic and describes the sound of a steam engine. This is typical of the Southern African languages. Other great examples are "Ixopo" (a town) and "ipeepeep". The "X" in Ixopo is an alveolar lateral plosive (the sort of click you do when communicating with horses) and the word describes the sound of cattle's feet sucking in mud - a real poetry! "ipeepeep" is a new word for "scooter"

Are you sure the language is Swahili and not Zulu? Swahili is East African and I can't imagine it having anything to do with any Southern African country.

Richard.