Gautrain is a seriously mis-designed project.  By international experience, high-speed rail is grossly unsuited to a short-range (50 or 60 km end-to-end) start-stop service.  The financial mismanagement (major ongoing subsidies in addition to exorbitant fare structures) built into the scheme speaks for itself.  
A minor improvement would have been to specify as capable of interworking with the existing suburban rail services, rather than specifying a rail-gauge standard imported from outside, and used nowhere else in the whole of Africa.