Disaster response: the Elios 3 in the Johannesburg gas explosion

Specialist digitization and inspection engineers Delta Scan used the Elios 3 in a rapid response to deal with a gas explosion on a street in central Johannesburg in 2023.

Benefits in a nutshell


The explosion made it impossible to safely reach the underground areas, but the Elios 3 gathered the necessary data without any risk exposure to the Delta Scan team.


Delta Scan could gather data in days, rather than months, providing key information to authorities thanks to the Elios 3.

Data quality

The maps and models generated by Delta Scan include detailed condition assessments of walls, pipes, and underground utilities.


 A traditional inspection of this area would take weeks to do, but the Elios 3 could be deployed as soon as Delta Scan arrived on site.




An underground gas explosion on Lillian Ngoyi Street in Johannesburg, South Africa in July of 2023 made global news. The videos circulating online showed a dramatic and sudden event that ripped the road apart and sent cars flying into the air. 1 person was killed and several more were injured. To secure the area after the explosion, emergency response teams had to determine the location of underground cavities where the explosion happened as fast as possible. They turned to the specialist inspection company Delta Scan. 

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The explosion tore up the street, leaving a huge amount of damage that was difficult to assess

Using confined space drones in emergency response 

Delta Scan is at the forefront of engineering and technology services. They specialize in infrastructure management and provide intelligence through digital analysis. They work across industries, from mining to major asset management and oil and gas. With a client list made up of asset owners, engineers, and insurers, they are revolutionizing complex engineering audits and surveying across South Africa and the wider region. 

Delta Scan has developed expertise in being adaptable to a variety of scenarios. They use LiDAR and specialized software to create as-builts and digital twins to determine the real condition of assets. They have been working with the Elios drones for the past few years, and use their Elios 3 for confined space audits. They have found it helps them to prioritize speed and safety in operations while maintaining the necessary quality for critical engineering decisions. They have used it for multiple emergency scenarios to gather high quality data in complex environments under time pressure. For this reason, they knew it would be the perfect tool to help them inspect the street affected by the explosion. 

fd773457-16aa-4adb-b03e-83ba03bbf571 (1)The Elios 3 being positioned over a manhole to enter the space beneath the street

Assessing a gas explosion with the Elios 3 

The Lillian Ngoyi Street explosion followed a straight line up the street, indicating it likely followed a service tunnel or pipeline. Authorities wanted to determine the possible causes of the incident, including whether it could have been a gas leak, illegal underground mining, or negligence. 

Delta Scan was contacted shortly after the explosion to investigate the underground cavities under the explosion area, with the pressure to get results as fast as possible. In the past, Delta Scan has mapped complex underground tunnels with the Elios, which is how the authorities knew they could get the job done. Delta Scan quickly arrived at the site of the explosion and immediately began their investigation. 

The mapping done by Delta Scan used the LiDAR and visual camera was intended to assess the integrity of existing support structures, the likelihood of further damages or collapse, and what utility services may have been affected or damaged. The drone is small, fitting into spaces as tight as 50x50 cm, which made it ideal for getting up close to the tunnel walls and identifying evidence that authorities could use for their investigation. Additional thermal cameras on the drone were used to determine if any cables were live.

The benefits of drones in underground mapping 

The data collected by the Elios 3 was pivotal in constructing accurate 3D maps of the underground service ducts. Over the course of 1 week, Delta Scan collected this data and inspected the condition of slabs, walls, and essential services. The drone’s small size and powerful lighting rig meant they could easily navigate the complex environment even when flying beyond the line of visual sight.

The data collected by Delta Scan empowered comprehensive analysis, including identifying cracks and damage

The nature of this project presented huge safety concerns. Traditional methods would have taken weeks or months to safely be put in place and data collected. Instead, the Elios 3 took just a few days. This was critical as Delta Scan had been told by authorities there was significant time pressure and they needed to get results quickly. 

Following the results produced by Delta Scan, the local authorities have received a detailed map of the damages above and below ground - with some of the aerial imagery captured by other drones flown over the blast site above the buildings. The map created by Delta Scan includes reference points of the locations of greater damage and drawings indicating the dimensions of the various service tunnels. 

Acting on drone mapping results 

The repairs to the damage are about to take place, and extensive planning is underway. The explosion took place in the central business district of Johannesburg, and the area is busy. Thus, the time savings provided by the Delta Scan team through using the Elios 3 have been key in starting the process of returning life on that street to normal. 

“Without the drone, the inspection would have been infeasible due to safety concerns. The drone was not just useful - it was indispensable for the task and unmatched by any alternative tool.” - Darryl Epstein, Managing Director at Delta Scan. 

The simultaneous generation of a LiDAR point cloud and visual data collection by the Elios 3 made it the ideal tool for this task

The City of Johannesburg said that the findings from Delta Scan’s results as well as other parts of their investigation will be used to upgrade and reconstruct the tunnels under the street. The investigation has led to many authorities requesting audits of the city’s aging infrastructure

Delta Scan highlighted the flexibility of the Elios 3 in handling a challenging environment. Despite smoke, dust, debris, and minimal light, the drone was able to complete the inspection as planned with the operations completed faster than any other method would have allowed. Between the skill and expertise of the pilots involved and the capabilities of the Elios 3, this critical mapping project was made possible with greater safety and speed. 

 Discover more about the Elios 3 and its specialized LiDAR payload. 


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