Metrorail says damage to one of its trains, which caught fire between the Bosmont and Maraisburg stations earlier on Tuesday evening, amounts to about R4.5 million.
The train, which was on its way to Johannesburg from Randfontein, caught fire just after 6pm.
Metrorail spokesperson Lillian Mofokeng said a faulty cable sparked the fire which resulted in two coaches burning out completely.
"No injuries have been reported and all commuters that were on board the train have been cleared," she said.
"Metrorail management thanks all emergency teams for quickly responding to the scene and extinguishing the fire. Currently, work is under way to clear the scene in an effort to ensure that no delays are experienced for the morning peak service."
Mofokeng said Metrorail management apologised for the inconvenience and assured commuters that their safety remained a priority.