South Africa’s rail bottlenecks threaten to curb coal deliveries to its main export hub for a sixth consecutive year, according to one of the biggest producers in the nation.

Shipments of the dirtiest fossil fuel by state-owned Transnet SOC Ltd. from mines mainly in Mpumalanga province to Richards Bay Coal Terminal are on pace to reach 47.4 million tons this year, Exxaro Resources Ltd. said in a statement Wednesday. That would miss Transnet’s own target and be the lowest level in at least three decades.

“Even though the coal export industry has supported TFR where opportunities arose, no improvement in tonnage railed has been experienced,” Exxaro said, referring to Transnet’s freight rail division. The logistics company didn’t immediately respond to an email requesting comment. 

Transnet has a turnaround plan to improve performance by its rail network to the ports it operates and has requested funding from the government in order to reach the higher targets. The company set a goal of shipping 60 million tons of coal to Richards Bay this year. 

Exxaro shares fell as much as 3.4% in Johannesburg Wednesday. The stock has slumped 13% in 2023, heading for its worst year since 2018.