Truck accidents add to incidents on MinRes' iron ore haul road.

A fifth road train crashed on Mineral Resources' haul road network two days after the lithium and iron ore producer ruled out another tragedy.

A multi-trailer truck transporting iron ore overturned on Saturday on the Onslow Iron haul road in Western Australia's Pilbara area, according to MinRes, heightening concerns about the network's safety following four accidents between August and November.

The fifth rollover occurred after Mike Grey, MinRes' chief executive of mining services, stated last week: "We haven't seen another incident [on the Onslow haul road since November] and nor should we."

Trucks transport up to 330 tonnes of iron ore from MinRes' mines to the port using this route. It is critical to the miner's cash flow, as its debt has risen to $5.1 billion due to its $3 billion Onslow Iron project and the lithium price drop.

According to MinRes, three crashes occurred on network side roads, while two happened on the significant haul route. The road was also devastated by a cyclone that dumped a month's worth of rain in 24 hours, which Mr Grey described as "a bloody unusual rain event".

MinRes, the country's largest crushing contractor, stated the tragedy occurred at 10 p.m. on Saturday after haulage on the road was halted for safety reasons due to a dust storm.

"When haulage resumed, a road train partially towed onto the haul road became stranded." "There were no injuries, and the trailers have since been recovered," the miner stated. The event was reported to the WA Department of Energy, Mines, Industry Regulation, and Safety.

MinRes sold a 49 per cent ownership in the 147-kilometre private haul road to a Morgan Stanley division for an initial payment of $1.1 billion. They will get an additional $200 million if the haul road reaches its planned capacity by 2026.

MinRes will get a fee for volumes of iron ore that use the infrastructure, regardless of whether the miner owns the ore.

Mark Wilson, MinRes' chief financial officer, stated that the rollovers between August and November "involved some degree of operator error" and that the miner has taken precautions to avoid future mishaps.

"We've included several operational improvements, strengthening driver training, looking at the road design, making improvements and improving signage and lane delineation," he told me. "We feel that we're in a good space there now."

During last week's results call, Jarden mining analyst Ben Lyons questioned the road's layout. "It's possible that the trailers have a design issue - perhaps the centre of gravity is too high? Maybe the transport road's design isn't right?" he asked.

The rollover is MinRes' latest setback, as its managing director and billionaire founder, Chris Ellison, is under investigation by Australia's corporate watchdog.

The Australian Securities and Investments Commission is investigating Mr Ellison on claims of business wrongdoing, spurred by The Australian Financial Review's reporting on an alleged offshore tax evasion scheme that enriched Mr Ellison and other executives.

MinRes shares rose 2.5 per cent to $35.34 on Thursday.