In a recent emergency in Lyon, the Elios 3 drone was deployed to investigate a mysterious sinkhole that had opened up underground. This innovative technology provided the only safe and effective way to assess the situation and gather critical data.

Key Benefits at a Glance

Lyon, known today as one of France's most vibrant cities, has a rich history dating back to Roman times. Once called Lugdunum, the city was a major Roman settlement founded in 43 BC. Today, remnants of that ancient past are still visible, with archaeological sites like the Théâtres Romains de Fourvière and the Jardin Archéologique drawing visitors from around the world.

However, beneath the modern streets lie the remains of Roman structures—old sewers, buildings, and storage areas—that can sometimes cause unexpected issues. As a result, local authorities remain vigilant in monitoring any signs of subsidence or ground instability, especially when it comes to areas with historical significance.

Local Authorities Turn to Technology for Emergency Response

In a residential neighborhood of Lyon, a large sinkhole suddenly appeared near an apartment building. The Lyon Metropole immediately recognized the potential danger—especially if the hole was connected to ancient Roman tunnels or structures below. If the cavity expanded, it could threaten the stability of the building and put lives at risk.

The sinkhole was close to a residential building, increasing concerns about the size and nature of the sinkhole

Xenodrone, a specialized inspection company, was called in to conduct a rapid assessment. Julien Gay, the company’s head, has experience in emergency response and understands the urgency of such situations. He believed the Elios 3, designed for underground operations, would be the perfect tool for this mission.

Responding to Land Subsidence with an Underground Drone

Upon arrival, Julien found a sinkhole just 2.5 meters away from the building wall. Given the presence of Roman ruins beneath the city, he suspected the cavity might extend into ancient tunnels. Without a drone, it would have been extremely dangerous to explore the area manually.

The Elios 3 entered the sinkhole without anyone having to go near it, keeping emergency response staff safe

Julien needed to determine if there was an immediate risk of further collapse and whether the cavern was expanding toward the building. To do this, he used the Elios 3 to collect LiDAR data and create a 3D model of the space. Thanks to the drone’s speed and accuracy, the entire inspection was completed in just 4 minutes.

Analyzing Subsidence with an Underground Drone

Inside the sinkhole, Julien flew the Elios 3 vertically down and performed a full 360-degree rotation to capture detailed data. The resulting point cloud provided a clear image of the cavern, which extended 6 meters deep. This information helped experts understand the scale of the problem and assess the risks to nearby structures.

As part of the report, Julien helped responders analyze the proximity of the cavern to the building foundations

Once back at the office, Julien compiled his findings into a detailed report using Inspector 5. The LiDAR data not only showed the size and shape of the cavern but also helped identify whether it was a natural formation or a remnant of ancient Roman construction. This information was crucial for the local authorities in planning their next steps.

The Flexibility of the Elios 3 Empowers Emergency Response

When dealing with unpredictable emergencies, the ability to act fast and safely is essential. The Elios 3 proved to be an invaluable tool in this case, allowing Julien to complete a thorough inspection in under 5 minutes. More importantly, it kept everyone out of harm’s way and provided reliable data that would have been impossible to gather otherwise.

“We pride ourselves on being able to respond quickly,” said Julien. “As a firefighter, I’ve seen how critical speed is in these situations. Now, with the Elios 3, we can inspect buildings on a daily basis, but it’s clear that our services are also vital during emergencies.”

Following the mission, the team discovered a hidden spring beneath the sinkhole, which was filled with 63 cubic meters of material to stabilize the ground. With the help of the Elios 3, the local authorities now have a clear understanding of the subsidence and can plan accordingly. They can even return to the site with the same drone to monitor future changes, overlaying new data onto the existing model for long-term tracking.

This case highlights the growing role of drones in emergency response and infrastructure safety. With their speed, precision, and ability to access hard-to-reach areas, drones like the Elios 3 are becoming essential tools for modern urban management and disaster mitigation.