The $US518 million autonomous train plan has been under development in the Pilbara for three years, and follows the deployment of 57 autonomous trucks at Rio's Australian iron ore mines.
Rio confirmed the autonomous rail system, dubbed AutoHaul, had its first proper trial in the Pilbara just before Christmas.
Fitted with radar, sensory equipment and mapping technology, the autonomous machines can tell when an object is blocking their path and can respond to reduce the likelihood of impact.
Autonomous equipment is designed to be more efficient, safer, cheaper and have less downtime than human-operated equipment, and Rio said it was already seeing proof of that from its trucks.
Rio has the largest fleet of autonomous trucks in the Pilbara and uses trucks produced by Japanese manufacturer Komatsu. BHP Billiton and Fortescue Metals Group also have autonomous trucks but use models produced by US company Caterpillar.
"This is not about displacing people from jobs. We are removing people from what has often been a dangerous job, ill-suited to people, and those same people have other opportunities," Caterpillar's regional manager Carl Hendricks said.