Former Transnet employee, Gerhard van der Westhuizen, is testifying at the judicial commission of inquiry into allegations of state capture on Monday.
Last week, chartered accountant Roberto Gonsalves took the stand.
He represents one of the minority shareholders in a consortium which benefitted from Transnet contracts for 1 064 locomotives.
The inquiry heard on Thursday how the price tag attached to the cost of relocating an assembly point for Transnet locomotives rose from R9.7m to R647m.
The commission, chaired by Deputy Chief Justice Raymond Zondo, is investigating allegations of corruption, fraud and maladministration at several state entities.