Update: this article previously stated FMG had expanded its fleet of autonomous trucks to 62, based on data provided by WesTrac. The company has since said it made an error and that number is 54. The article has been updated accordingly.
Fortescue Metals Group has found the fleet of autonomous trucks deployed at its Solomon Hub mines has significantly cut costs and boosted productivity compared to its manned vehicles.
The miner introduced Caterpillar autonomous trucks - provided by Seven Group Holdings subsidiary WesTrac - in 2012.
Last August Fortescue said the autonomous haulage system it had introduced at the Firetail and Kings Valley iron ore mines had moved over 200 million tonnes of material since 2012.
The miner has steadily grown its fleet of Caterpillar autonomous trucks since the project's inception after overcoming some early hiccups like vehicles stopping for puffs of dirt in the road.
The total number of trucks to be delivered under the original contract was 45, but Fortescue has soared past that number after finding better-than-expected benefits from the autonomous approach.
The head of technology and innovation for WesTrac parent Seven Group Holdings James Scott said 54 vehicles were now in operation.
Speaking at the AWS Summit in Sydney, he also shed some further light on the gains Fortescue was seeing from the vehicles.
Scott said productivity had increased by 20 percent over the traditional manned fleet, and Fortescue's pit to port costs had fallen by 43 percent.
WesTrac supports 54 autonomous trucks with Fortescue and 80 in the broader Pilbara region.