The rise of machines that have been described as "the world's largest and longest robots" - trains used to carry iron ore in the Pilbara - has stepped up a gear, with Rio Tinto getting approval for its autonomous trains from the rail safety regulator.
The miner said in financial filings it had received regulatory approval for the project, a key step in its bid to haul ore from pit to port completely autonomously by the end of this year. Rio Tinto will take a phased approach to deploying autonomous trains across the network in the lead up to full commissioning.
The project, known as AutoHaul, had first trains start running in autonomous mode with a driver on-board monitoring operations in the first quarter of 2017.
According to a statement from Rio, by the end of the first quarter of 2018, around 65 per cent of all train kilometres were completed in autonomous mode - around three million kilometres in total.
Rio Tinto operates about 200 locomotives on more than 1,700km of track in Pilbara, transporting ore from 16 mines to four port terminals.
"(The regulator) has granted Rio Tinto accreditation for the autonomous operation of trains, after it provided evidence of its competency and capacity to manage the risks to rail safety associated with this technology", he said.
It is understood no decision has been made on what Rio Tinto's train workforce will look like in the face of complete automation.