Johannesburg CBD Road Explosion underground.



On the 19th of July 2023, the Johannesburg CBD Road Explosion occurred. A blast in the Johannesburg CBD turned old Bree Street, a bustling main road for commerce and trading, into a post-apocalyptic war scene. As the story unfolded, a methane gas build up in the underground tunnel networks was found. This was found to be the cause of the deadly explosion. The Johannesburg CBD road explosion has killed 1 person. Several were injured and was the explosion was the cause of major road and infrastructure damage. As well as major disruptions to basic services such as water and power supply in the area.

To explain a-little bit more of how this happened, Methane is lighter than air so usually methane, will go up. The gas travelled up along the service tunnel from an unknown source to the crest of the tunnel near Bree Street. This is the same reason why there was no fire after the explosion. Since gas explosions result in the perfect dilution of gas to air, the threshold of this is between 5 and 15%. If it’s between 5 to 15% it is explosive. If the concentration of gas to air is anything above 15% then it is combustible. The investigation ruled out several other suspected causes which includes Gas Leakage. Illegal mining underground and site negligence. While the ignition source was not pin pointed, many illegal electrical connections and ill maintained electrical supply cables are the most plausible source.

After the explosion:

Delta Scan mobilised to site the day after the explosion and was used to lead the underground inspections while the environment was still being assessed for safety. With the deployment of our specialised confined space drone, ELIOS 3, we were able to begin assessing the underground infrastructure for integrity.  As well as possible causes of the blast and casualties. Delta Scan was able to enter and visually assess an environment that was not safe for humans to enter. This was due to gas content in the environment as well as the unknown stability of the structure.

The investigation:

Immediately upon entering the underground network, and flying away from the blast epicenter, the Delta Scan team identified serious structural cracking. The cracking occurred on the soffit of the underground tunnel network. These happened to be where emergency personnel had established a hub. As well as local community members had gathered to view the damage. We were able to warn them of the danger and establish a safer barricade perimeter around the site.

Using the Elios 3 and our powerful AI algorithms, we were able to show the city what dangers lurk below the surface of the city. With the use of video data, AI and reality capture techniques, we were able to freeze the damage in time. This was done for assessments and investigations to carry on offsite and for the city to commence clean up and rehabilitation as soon as possible. In the past the site would have to remain intact until investigations were complete. This resulted in communities living with the consequences for weeks or months.  By capturing the site in this manner, returning to normal life for the surrounding communities becomes a lot more efficient. By allowing professionals to carry out the investigations with less pressure, off site with unseen areas exposed, resulting in the most effective and efficient delivery of reports.


Project Details:

  • Damaged Area: 3 city blocks, 0.5km of Road
  • Response time: 24 hours
  • Reporting time 24 hours