FLYWEL in Oosterweel Magazine - The Flying Surveyor
Using Propeller, an Australian software platform, these drone images provide a wealth of information for everyone involved in the project, primarily the surveyors.“We are currently one of the largest users of that platform in the world. For us, these images are invaluable every single week,” explains Bert Limbos, head of Surveying at ROCO. “It has become an indispensable method for collecting data on the site's progress. For example, we are currently mapping soil stockpiles. In the past, if you wanted to know how many cubic meters were there, you had to send a surveyor to the site. They would measure hundreds of points on location and then perform calculations. Today, we can calculate the volume in the software program. It’s child’s play, and you can’t imagine how much time it saves, particularly in terms of personnel travel. Additionally, there’s the cost difference. A surveyor's equipment costs a multiple of a drone."
Theory and Practice
The return on investment is therefore enormous. “Speed is also a major advantage because the construction site evolves rapidly, and this will only increase in the coming years,” adds Dave Wels. “By now, the team relies on this data. We notice their reactions when, for example, we inform them that we can’t fly due to rain. Once all subprojects are fully launched, we won’t know where to start measuring. We’ll probably need more than one drone by then.”
Does this make traditional surveyors obsolete? “No, because you can’t use these images to position a bridge with millimeter precision. Surveyors still have an essential role to play on-site.”
The drone recordings primarily serve to overlay the 3D design onto the current reality. “The entire plan of our construction sites is drawn in a BIM model (read more on page 33),” says Bert Limbos. “Once everything is built, we measure it again. Designers can then assess whether there are deviations from the design. In this way, in ten years, we will deliver Lantis a 3D model of the as-built construction, showing exactly how it stands. Future generations will know, for example, the precise locations of utility lines and structures. Currently, we don’t always know exactly what’s underground.”
"You can’t imagine how much time a drone saves, particularly in terms of personnel travel."
— Bert Limbos, Head of Survey at ROCO
Japanese Millipede
“This is the first time so much data is being generated using drones,” adds Dave Wels. “It’s quite different from someone just taking a photo. That’s a snapshot that doesn’t reveal what happened in the weeks before or after. We also create snapshots, but they are taken weekly, allowing us to archive the site’s history. We must ensure this massive archive is well managed.”
The drone isn’t only used for construction measurements but also for tasks like work preparation, positioning site installations, inspections, and more. For example, when certain areas of the site are handed over, the images are used to verify the exact locations of machinery or tanks and whether soil testing is required before the zone is returned to the client.
There are even unexpected applications. For instance, the Environmental department uses the drone images to identify where Japanese knotweed is growing. With the rapid advancement of artificial intelligence, it’s likely that such plants will soon be automatically detected.
Another example involves administrative use. There have been cases where drone images served as evidence to dispute an invoice. The accounting department could see, in black and white, that the rented machines had been on-site for a shorter period than the rental company claimed.
Automated Flying
Operating drones involves a fair amount of paperwork. A drone cannot simply take to the skies; the pilot must submit a request to air traffic control (Skeyes) through an app, at least three hours in advance—or, in some zones, eight working days before the flight. The proximity of the port, the city center, Deurne Airport, and the approach routes of other airports makes the airspace around Antwerp particularly tight. Despite this, the process of requesting flight permissions appears to run smoothly.
The situation is different when it comes to the “drone in a box”. This device is designed to have a fixed station and charging dock at the construction site, from which it can take off autonomously to capture footage. Unlike a traditional drone, it can be controlled remotely from a command center, flying beyond the visual line of sight of the pilot along a pre-programmed route.
“The process of obtaining permits for this, however, is not going as smoothly,” explains a spokesperson. “As a result, the new automated drone has been sitting idle for several months, waiting for approval. The Directorate-General of Civil Aviation is understaffed, and the file remains stuck in the pile.”
"We also create a snapshot, but one that is repeated weekly so that we archive the history of the construction site."— Dave Wels, Drone Pilot at ROCO
For Tunnels and Sewers
Meanwhile, another type of drone is in use, a so-called Elios 3 drone, affectionately called "bolleke" (little ball). Dave Wels uses this drone through his company FLYWEL, together with Dirk Caestecker from Medexon. It is designed for inspections in confined spaces, such as tunnel shafts or pipelines. A safety cage prevents the propellers from hitting objects.
The device is equipped not only with a camera but also with a LiDAR scanner. As a result, "bolleke" returns from a flight with a complete point cloud— a 3D dataset with all dimensions and volumes (see photo below). According to Dave Wels, this is primarily much safer. "Just last week, for example, we flew in a sewer. It's better to send a drone in there than to send a person down and put them in a boat. If something goes wrong, the consequences are more severe. Plus, you collect far more data. If you send someone, they only inspect the damage, and afterward, you’re left with just the photos they took."
It’s clear that drones today are as useful for a contractor as an excavator or a crane. Dave Wels sees even more possibilities for assisting with construction sites from the air. "Think about site security. A camera mast always has blind spots, whereas a drone doesn't. Or even transportation, from a warehouse to a construction site. Even if it’s just to pick up a forgotten box of screws, so no one has to return to the warehouse for it."
Drones in Bird's Eye View
- 2 million m²: The area that ROCO's drone maps in 3D on a weekly basis.
- 2 to 3 centimeters: The level of accuracy with which a construction drone can perform measurements from the air.
- 150: The number of GCPs (Ground Control Points), the black-and-white markers on the ground.
