Two trains collided on a key South Africa mining-export line, closing a route plagued by issues that have brought railings to Africa’s biggest coal port to a three-decade low.

Workers are trying to clear the trains that derailed in the incident, which occurred outside Richards Bay on the country’s east coast, state logistics company Transnet SOC Ltd. said in a statement on Monday. No serious injuries have been reported and the collision is under investigation.

The disruption comes as Transnet struggles to improve its performance, particularly on the line that transports coal from mines in South Africa’s Mpumalanga province to the Richards Bay Coal Terminal, the biggest facility of its kind on the continent. Volumes have dropped as the state-owned company has had to deal with derailments, equipment shortages, vandalism, corruption and poor weather.

Rail inefficiencies in 2022 cost South Africa’s economy 411 billion rand ($21.8 billion), and worsened the government’s tax shortfall, according to budget data. Companies including Thungela Resources Ltd., Glencore Plc and Exxaro Resources Ltd. exported 50.4 million tons of coal through RBCT in 2022, the lowest volume in 30 years. The companies didn’t respond to emailed requests for comment.

Transnet is also in financial trouble. The National Treasury last month agreed to provide a 47 billion-rand ($2.5-billion) debt guarantee to the company, making about half of the amount accessible to meet immediate obligations.

While the problems at Transnet have led it to collaborate with the government and business to address the constraints, those efforts have yet to yield a turnaround in the company’s operations. A tour in November showcasing Transnet’s rail facilities was delayed by vandalism and the theft of copper cables along the tracks, while broken signals forced the train driver to take instructions from the main control room via mobile phone.