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.

Rio made the announcement on Friday, adding that its $US940 million AutoHaul project was on track to be completed by the end of this calendar year.

Rio Tinto Iron Ore AutoHaul team celebrating the success of the first autonomous rail journey from Wombat Junction to Paraburdoo.

“Rio Tinto will take a phased approach to deploying autonomous trains across the network in the lead-up to full commissioning. Once commissioned, the network will be the world’s first heavy haul, long distance autonomous rail operation, unlocking significant safety and productivity benefits for the business,” Rio Tinto said in a statement to the ASX.

The vast trains consist of two or three powerful locomotives, along with 240 ore cars. When loaded each car holds about 118 tonnes of ore, meaning that a single train can transport about 28,320 tonnes of ore from mine to port.