Drone technology can add value to ground engineering by maximising the amount of data captured during site investigations.
Drones – or unmanned aerial vehicles (UAVs) – are already well established on many construction sites and engineering projects. Nowadays they are used for progress tracking, site walkovers, desk studies and asset inspections.
Overall drones have become a more viable option for various types of surveying and inspection work as the technology has developed, costs have come down and regulations have been updated.
Clients are also requesting digital twins of sites, meaning techniques such as photogrammetry, lidar scanning and drone surveys have been adopted to assist with 3D site mapping.
Atkins senior engineering geologist Craig Parry notes: “Drone technology in its modern form - equipped with photogrammetry and lidar - has been around for 10 years or more.
“It’s nothing new in that regard. But its application in ground engineering used to be undertaken by specialist contractors. The specialist topographical survey contractors had the drones and all the licences. So, the drones weren’t used by consultants in-house.”
Companies are now offering in-house drone training
This, however, has now started to change with the introduction of cheaper technology and the feasibility of in-house drone training.
Parry leads the infield data capture side of Atkins’ digital ground engineering team which covers areas such as building information modelling (BIM), common data environments, geographic information systems (GIS) and automation. The consultant has around 14 geotechnical engineers and engineering geologists trained in the use of drones. The training itself is approved by the UK’s aviation regulator, the Civil Aviation Authority.
“Advances in automation and data capture tools make it [drones equipped with the technology] a lot more accessible for people who haven’t had that full survey grade training,” Parry says.
Atkins associate engineering geologist Richard O’Brien, who is the discipline lead for digital ground engineering, adds: “Computing power has enabled us to do more as well. Creating 3D models for visualisations of the site is relatively straightforward these days.”
Once drone data capture is completed, the information is delivered into the cloud for processing and then ends up in the same location as the rest of the project data. In addition, the GIS software that Akins uses can generate BIM-compliant outputs.
In the early days of drone technology adoption, the devices were often employed before site investigations even began. A drone survey would be carried out as part of a topographical survey to collect baseline information.
Parry thinks this has changed with drone surveying now encompassing all stages of a project, as the technology can offer value from start to finish.
“There’s still benefits doing it at the start and having a 3D model of the site for people who haven’t even been to the site to then be able walk around it virtually,” Parry notes.
In the intermittent stages, the technology can be used on active sites to monitor changes and see how the project is developing. This way senior management and those who do not have regular access to the site will also witness the progress over time.
“They can slide the slider bar at the bottom of the screen and see what’s changed over time, and see how volumes have moved, where materials have moved on site and where things are progressing,” Parry adds.
In ground engineering specifically, drones are also now being used for more specialist purposes.
“For us, it’s maximising that initial data capture and making use of it at any opportunity. We get a lot from it in the initial site walkover and then the more detailed inspections,” Parry says.
The technology also enables geotechnical engineers to see things from a new perspective to get a bigger picture of the site they are inspecting.
A key area in which Atkins is utilising its drone and digital site data collection capabilities is in the monitoring of potential geohazard movements and failures such as landslides over time.
“You’ve got your control points and you’re going back regularly to undertake surveys, and you can see where changes are taking place and where things may be moving on site,” Parry explains.
Atkins’ ground engineering teams also carry out rope access work to inspect rock slopes, but this can be dangerous.
“It’s one of the riskiest activities we do,” he adds. “You always want to see if there are any other ways of capturing that data without going on the ropes, because it’s the last resort for safety reasons.”
The team can instead use a drone carrying a digital camera to get into the trickier locations to produce a model of the parts of the site that could previously only be accessed by rope.
“It’s not completely removing the need for rope access in some cases, but it’s enabling us to better plan where to do it. So, we minimise the amount we’re actually on the ropes and it’s better planned to get that information.”
Digital cameras on today’s drones can capture high resolution images down to millimetre resolution and centimetre accuracy, depending on the flight height and technology.
Drone providers have also been working on artificial intelligence capabilities to help automate the process of data capture. Although, as Parry points out, while the new technology is out there, operators still need to understand the required workflows to provide reliable data.
The technology is also still limited by wind speeds and heavy rainfall, meaning some flexibility is needed for survey scheduling.
“It’s having to change the client’s mentality on flexibility as well. So, where the drone is part of the requirements, you have to be quite reactive. I don’t think I’ve studied the weather so much before, until I started doing this drone work,” Parry says.
“But that technology is changing; there are providers who are starting to offer drones which are water resistant or can fly in in the rain. Drones are also getting a bit better at managing wind. But at the moment it’s an area which could be improved upon.”
In addition to technological improvements, new potential applications are also being identified. Drones used in ground engineering could, for example, benefit from the use of magnetometers, thermal sensors and other geophysics tools. These will become more common as costs come down and the technologies become more accessible.
On 31 December 2020 the Civil Aviation Authority (CAA) changed the rules for flying drones to be based on risk instead of whether they are being used for commercial or recreational purposes.
Drone users need a flyer ID and operator ID, and then the requirtement for CAA approval depends on the “risk” of the flight.
Applying the new rules depends on where a drone is flown, proximity to other people and the size and weight of the device. In effect, the lighter the drone, the more freely it can be used.
Approval just to operate a drone commercially is no longer required.
The “Open” category is intended for low-risk drone flights, for example for flying a very light drone or flying a drone in the countryside. People flying drones in this category need no specific authorisation from the CAA.
But for higher risk flights, for example over urban areas, operational authorisation from the CAA is still required. Commercial operators in the UK are also required to have public liability insurance.
Extended visual line of sight (Evlos) drone authorisation also allows remote pilots to be supported by observers who can maintain visual line of sight with the drone and communicate risks back to the pilot. This enables flights further than 500m from the remote pilot.
In 2020, the CAA granted Atkins an Evlos permit to conduct a drone survey from up to 198m above ground level, within a range of 1.5km from the drone pilot. This was to enable the consultant to track progress across the Hinkley Point C construction site.
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