Illegal tunnelling beneath Joburg’s M2 has hollowed bridge supports and risks collapse, JRA warns

Illegal tunnelling by zama‑zamas has hollowed out ground beneath sections of Johannesburg’s M2 highway, creating deep cavities and sinkholes that threaten bridge abutments and access to the CBD, the Joburg Roads Agency (JRA) has warned. The agency says inspections have identified extensive structural defects and it is assessing repair works and short‑ and long‑term interventions.

What authorities found

The JRA reported collapsed paving, embankment erosion, damaged and collapsed bridge abutments, deep cavities and sinkholes linked to illegal tunnelling activities beneath parts of the M1 and M2 in the inner city and Selby areas. The agency listed affected locations that include the M2 at Heidelberg Road, Booysens Road, Pixley Ka Isaka Seme (Sauer) Street and Simmonds Street, as well as sections of the M1 North near Booysens Road. Similar defects were noted at the M2 underpasses at End Street and Heidelberg Road, and beneath the M2 East Bridge in Selby and Booysens.

Official responses and technical concerns

The department of mineral and petroleum resources (DMPR) confirmed its Johannesburg team visited the area but said:

“Our Johannesburg team went to the area. We realised that the department of transport should handle the issue rather than DMPR.”

Mining expert David van Wyk told the publication that the problem is aggravated because some bridge supports were built using tailings waste rather than building sand. He said the tailings contain toxic heavy metals and that the supports are compromised because the sand used contains gold. He warned of wider geological concerns tied to abandoned mines south of the M2 where acidic water is accumulating and affecting dolomitic substructure.

Damage beyond structural erosion

JRA said additional damage has been recorded on surrounding infrastructure, including theft of handrails and guardrails from the Heidelberg steel bridge, ongoing illegal dumping, vandalism and the establishment of informal encampments under bridges. The agency also flagged stormwater drainage blockages and ongoing erosion as factors that have worsened abutment conditions.

Work already under way and planned repairs

JRA described a programme of short‑ and long‑term interventions. In the short term, it will continue with extensive stormwater maintenance to address drainage blockages and reduce erosion, and it is collaborating with the Joburg Metro Police Department to monitor hotspots and remove illegal makeshift structures around bridges.

The agency has appointed a consultant to conduct a comprehensive investigation and to design permanent repair solutions for the affected abutments and parapet walls along the M1 and M2. JRA said investigations to date include environmental and heritage studies, hazardous materials cleaning, jetting and CCTV inspections of stormwater systems, and detailed measurements at each abutment site.

Planned works will cover the repair and upgrade of abutments and parapet walls and related stormwater drainage. JRA also said that post‑construction each site will require cleaning to remove hazardous objects and 24‑hour security due to the locality and socioeconomic issues of displaced individuals seeking shelter. The agency is exploring alternative materials to deter theft and vandalism and to protect completed repairs.

History and wider risks

JRA said the problems were first identified in routine inspections in 2016. The agency noted that in 2019 illegal tunnelling beneath the M1 North embankment at Booysens Road caused significant damage that required rehabilitation, and assessments in 2023 found the southern abutment of the M1 North bridge at Booysens Road had partially collapsed largely because of severe stormwater drainage blockages and ongoing erosion.

While the extent of excavation varies by location, JRA stressed that investigations have revealed extensive underground tunnelling and the formation of deep cavities beneath and adjacent to key bridge structures, creating significant risks to the road network and public safety.

What happens next

JRA is continuing technical assessments and preparing repair designs while coordinating short‑term stabilisation, drainage maintenance and security measures aimed at reducing immediate risk to users of the M1 and M2. The agency said protecting completed solutions from future damage will be part of the long‑term programme.