South Africa is facing rapid urbanisation marked by challenges such as overpopulation and poor mobility associated with urban growth. Since urban mobility depends on transportation, it requires transport infrastructure that is socially, economically and environmentally sustainable, and fit for purpose. Hence, there is a need for environmentally sustainable transport infrastructure that also meets social demands and is economically viable. This kind of transport infrastructure is sometimes referred to as "green transport infrastructure" (GTI). However, relevant for present purposes is the fact that GTI is as costly as it is desirable. Traditionally, urban infrastructure is financed by the public sector. However, alternative means of finance must be sourced to cater to the increasing needs of society for economic and social infrastructure. These alternative means of finance include borrowing or attracting capital from private investors. The success of private investments in public transport infrastructure depends on whether South Africa's legal framework makes provision for the protection of investments to facilitate a well-established investment climate for GTI. Therefore, the question is whether South African investment and local government law and policy enable or frustrate private investments in GTI. The study discusses the dynamic and functional relationship between private investments and the development of GTI that needs to be regulated by South African law. It is revealed that there are gaps in the law regulating private investments in GTI; but there are also specific legal provisions serving as a conduit for establishing a more robust South African legal framework for private investments in GTI.