CASE C31 · ZA · 2023
Johannesburg: LiDAR drone survey of underground service tunnels after a street gas explosion
In July 2023 an explosion under a street in central Johannesburg damaged underground service tunnels and ducts. Delta Scan flew a caged drone with LiDAR and thermal cameras through small openings to record damage where people could not enter. The duration is stated inconsistently, and smoke, dust and darkness hampered the work.
Underground tunnels & utility conduitsConfined spacesGNSS-deniedDarknessDust & smokeExplosive atmospheresUrban areas & people belowStrong electromagnetic fields
| Owner | City of Johannesburg / emergency authorities |
| Provider | Delta Scan |
| Location | Lilian Ngoyi Street, Johannesburg CBD, South Africa |
| Aircraft | Flyability Elios 3 with LiDAR payload; other drones for aerial imagery |
| Sensors | LiDAR, visual camera, thermal camera (to check live cables), lighting rig |
Before
Conventional inspection after making the site safe, said to take weeks or months.
With drones
After the July 2023 explosion, the drone entered service tunnels through openings as small as 50×50 cm, mapping damage and cavities with LiDAR and thermal imagery.
Outcomes
| Metric | Value | Basis |
|---|---|---|
| duration | data collection about one week (the page also says the project took a few days) vs weeks or months | Reported |
| use of results | findings used by the city to plan rebuilding of the tunnels | Reported |
Caveats & limits
- Manufacturer case study; duration is stated inconsistently.
- Smoke, dust, debris and darkness hampered the work; success was partly credited to pilot skill.
- The cause (gas pipeline vs other) is not confirmed in the source.
Sources
- Disaster response: the Elios 3 in the Johannesburg gas explosionFlyability Full text read
Sources checked: 2026-10-22