The 'driver' operates a dead man switch in a lot of cases, and that's about it. I can't recall if this train itself was an automated test bed, but a lot of BHP and Rio's rail operations are managed from the control center in Perth, and drivers are (usually :P ) aboard in case of problems.

Edit:

So it looks like even though they've had the technology going for a while, Rio only just delivered their first 'real' loaded autonomous ore train last year : https://www.riotinto.com/ourcommitment/spotlight-18130_25692...

More on the AutoHaul system: http://www.calibregroup.com/projects/project/autohaul-projec...

Apologies for the mixup