Illegal mining is increasingly threatening Johannesburg’s roads, electricity infrastructure, buildings and residential areas, with underground excavations destabilising land and damaging structures across parts of the city.
The warning comes as abandoned gold mine shafts beneath and around Johannesburg are being reworked by illegal miners, commonly known as zama zamas. Residents and officials say the activity has contributed to road collapses, cracks, sinkholes and damage to public infrastructure.
Along Wemmer Pan Road, sections of the road have collapsed, while cracks and sinkholes have appeared in areas where miners are conducting underground blasting in search of gold and other minerals. Residents in affected communities have also reported feeling tremors from mining activity beneath their homes.
The risks extend to Johannesburg’s electricity network. City Power spokesperson Isaac Mangena said underground excavations have compromised ground stability and placed substations, transformers, pylons and transmission towers at risk. In some locations, infrastructure has already begun to sink as mining activity expands beneath the surface.
City Power has identified areas including Robertville, Roodepoort and the Main Reef corridor as major concerns. At the Robertville substation, continued illegal mining has worsened ground instability identified through geological assessments, while similar problems have been observed around the Roodepoort substation.
The problem is also affecting major roads. The Johannesburg Roads Agency has identified extensive defects beneath sections of the M1 and M2 motorways, including eroded embankments, damaged bridge structures, deep cavities and sinkholes associated with illegal tunnelling, as well as theft and vandalism of infrastructure.
The M2 highway has faced particular concern, with illegal excavation and the removal of material from bridge support structures creating additional risks. The Roads Agency said some of the affected locations include sections around Heidelberg Road, Booysens Road, Simmonds Street, Sauer Street and the M2 East Bridge in Selby and Booysens.
The infrastructure damage comes on top of the security problems associated with illegal mining. Residents and local officials have reported criminal activity and violent clashes linked to competition between mining groups. Some communities say they are living in fear as armed groups operate around abandoned shafts and informal settlements.
South Africa’s government has increased security operations against illegal mining. President Cyril Ramaphosa deployed members of the military across Gauteng in March to support police operations targeting crime and illegal mining in the province.
The scale of the challenge remains significant. Mining expert David van Wyk estimates that more than 34,000 irregular miners are operating in South Africa. He has warned that the long term consequences could include further damage to buildings and infrastructure, particularly in communities situated on or near old mining areas.
Authorities are pursuing both immediate and longer term measures. The Johannesburg Roads Agency is carrying out stormwater maintenance and temporary stabilisation work while developing permanent repairs for damaged bridge abutments and other structures. It is also examining alternative construction materials that could be less attractive to thieves.
City Power is similarly strengthening parts of its electricity network to maintain alternative supply routes if mining related instability forces infrastructure to be shut down or relocated. However, the utility says some interventions could be costly, particularly where entire substations may eventually need to be moved.
The situation highlights a broader development challenge for Johannesburg, where the legacy of gold mining intersects with rapid urban development, infrastructure maintenance and organised criminal activity. Preventing further damage will require sustained enforcement alongside the rehabilitation and securing of abandoned mine workings.
Without effective intervention, continued underground excavation could increase the cost of maintaining essential infrastructure and expose residents, businesses and public utilities to greater risks of land collapse, service disruptions and structural damage.
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