Johannesburg CBD Road Explosion


On the 19th of July 2023, the blast of the Johannesburg CBD road explosion occurred. This explosion 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 had built up in the underground tunnel networks. This was found to be the cause of the deadly explosion. The Johannesburg CBD road explosion had killed 1 person, injured several and was the cause of major road and infrastructure damage. This caused major disruptions to basic services such as water and power supply in the area.

How the explosion occurred:

To explain a bit more about how this occurred, methane, being lighter than air, typically rises. The gas travelled up the service tunnel from an unknown source to the crest of the tunnel near Bree Street. This is also why there was no fire after the explosion, as gas explosions result in the perfect dilution of gas to air. The threshold for this is between 5 and 15%. If the concentration of gas to air is between 5 to 15%, it is explosive. If it’s anything above 15%, then it is combustible. The investigation ruled out several other suspected causes. These including gas leakage, illegal mining underground, and site negligence. While the ignition source was not pinpointed, many illegal electrical connections and poorly maintained electrical supply cables are the most plausible sources.

The day after the explosion, Delta Scan mobilized to the site and led the underground inspections. As well as assessed the environment for safety. Deploying our specialized confined space drone, ELIOS 3, we began assessing the underground infrastructure for integrity. We looked for potential causes of the blast, and casualties. Delta Scan entered and visually assessed an environment deemed unsafe for humans. This was due to gas content and the unknown stability of the structure.

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

How we used our Elios 3

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, 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, perhaps resulting 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, and 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