With construction firms leading the way in drone technology, Claire Cameron takes a closer look at how unmanned aerial vehicles (UAVs) can be used onsite
THE use of drones in the construction industry has soared in recent years with almost a fifth of firms utilising flying robots to scope out work and monitor projects.
From surveys and site inspections to reducing health and safety risks onsite, the sector is one of the top five industries leading the way in unmanned aerial vehicles (UAVs), according to the UK Drone Usage Report 2016.
So why should construction companies adopt the technology?
While the traditional method of manually surveying a building is still fundamental, it does have limitations, explains Paul MacMahon, architectural assistant at rg+p, who says the immediate benefit of using drones is the ability to obtain otherwise impossible views of buildings, potential development sites and landscapes.
The multi-disciplinary practice uses imagery and data from drones to survey rural and inner city development sites to assist with every stage of the construction process, from design through to completion.
“Deploying a drone is quick and the amount of new information that can be acquired from these unique aerial views, up to 120m in the air, enables more thoroughly informed decision-making across all stages
of the design and construction process,” explains MacMahon, who holds a Civil Aviation Authority PfAW licence in order to fly drones.
Using drones eliminates cherry pickers, scaffolding and the need to put surveyors in danger by working at height, explains Lee McDougall, director, Geomatics at AHR Building Consultancy. They also have the ability to significantly reduce cost, effort and time by increasing flexibility.
“In the past, if a survey was planned for a particular day and then the weather was poor, rescheduling was a time-consuming and costly exercise, whereas with a drone a re-shoot is a very simple procedure,” he says.
“This in turn means minimal disruption and reduces timescales, which can be particularly important in environments such as education or residential, where disruptions to teaching schedules and intrusions to residents is vastly minimised.”
With almost 40 years’ experience working on everything from office fit-outs to the restoration of listed buildings, family- run construction firm Pexhurst has recently purchased its first drone.
As an onsite experimental exercise, the Hertfordshire-based contractor has invested in a Phantom DJ4, which managing director Martin Vella hopes will reduce the cost of preliminary project work.
He expects the “fairly easy to operate” drone, which benefits from auto pilot features and a return to home button, to add value to his business “by speeding up the entire process, allowing us to get back to clients more quickly on projects, tenders and feasibility investigations”.
Having carried out extensive stonework packages and external repairs in recent years, Vella says that although the use of a drone wouldn’t have changed the quality of the work undertaken and delivered, “in the early survey stages it would have allowed us to turn things round quicker and at lower costs”.
Keen to offer its clients certainty on the cost of a project wherever possible, Vella – a member of a flying club affiliated to the British Model Flying Association (BMFA) – explains the flight time of the Phantom DJ4 was an important factor in Pexhurst’s choice.
“This drone has a 28-minute flight time, which is generally long enough to survey the kind of sites we work on and it delivers outstanding high definition quality imaging too.”
Egg Homes founder Chris Nelson says the use of drone footage has been vital to progressing the build work at the Lake District’s Viver Green – a development of 19 homes that combine contemporary design with the latest energy-efficient technology.
“A drone allowed us to capture the key stages of the development process, which is invaluable when providing updates to purchasers, investors, financial institutions and various stakeholders on the build progress,” he says.
“It also allowed us to see the building work from angles we wouldn’t usually be able to and rectify any potential issues or snags immediately.”
As one of the first contractors to adopt UAVs, Costain recently repaired the storm damaged Dover sea wall – a high risk project made safer by using drone technology.
The engineering solutions provider deployed a high spec Falcon Asctec Trinity UAV to take high definition photographs of the permanent rock armour and a topography survey to speed up the repair process.
“We were dealing with a very unstable and damaged sea wall,” explains Peter Slater, aerial solutions manager at Costain.
The use of an UAV eliminated the need to access dangerous rocks so less time was spent onsite which was safer, reduced cost and saved time, he explains.
“It took a day-and-a-half to survey with a drone whereas to manually survey the entire area to the same degree of accuracy would have taken two people around two or three days,” he says.
“By using the drone we were able to look at the pictures from the safety of the office and produce a 3D model, which could then be matched alongside the design specification.” Using just a battery-powered unit, drones can also substantially reduce carbon emissions, explains Slater.
“We worked out even though we had to drive down to the site there was still an 80-90 per cent carbon footprint reduction.” And by not needing as many workers on site, contractors “can expect to save 30-40 per cent cost reductions on a daily basis”.
And this means construction firms “can complete more projects and cut across different sectors with the same sized workforce,” explains Slater.
Using drone photography alongside laser scanning, GPS and 3D modelling is also proving useful in surveying historic buildings for conservation and maintenance work.
AHR Building Consultancy recently use the technology to survey Lichfield Cathedral – a Grade I listed medieval building in Staffordshire.
To capture accurate data of the English Gothic architecture using conventional surveying techniques would have been time consuming, explains MacMahon, who says “the decorative nature of most historic buildings means that they involve particularly complex forms”.
And with conservationists keen to avoid physical contact, both drones and laser- scanning offer non-contact survey methods.
To increase accuracy, a 4K drone with a high pixel count was used at Lichfield Cathedral, which allowed the drone to get close to the fabric of the material and minimise shadows, says McDougall.
“With our technologies the data collected is accurate enough to capture not only every stone but also the details of every instance of wear and tear on this remarkable heritage asset.”
And while drone images are enough for a condition survey, the real “magic is in the combinations,” says McDougall, who explains the use of drones, cameras, laser scanning and GPS together produces accurate measurements for 3D models, which can be presented back to the client.
At Lichfield “we created highly accurate 2D CAD drawings of the floors, elevation, sections and roof and with a particular focus on obtaining otherwise very difficult to access aerial shots of the Library and Chapter House.
“From the photographs we were also able to create an intelligent photographic 3D roofscape using 3D Point Cloud and Mesh processing software.
“The resulting models provide the client with an extensive and highly accurate record of the entire building from which to plan repair and maintenance programmes.”
With the construction industry constantly evolving, cost-saving technology like drones can make work simpler and quicker, which “can be the difference between projects going ahead or not,” says Vella.
As a big advocator of using and analysing drone footage throughout the build programme, Nelson believes developers of all sizes will be using the technology in the near future, while MacMahon says rg+p is already planning for the technology to soar.
“We have been preparing with experimental flights in controlled conditions, for instance in different weather or times of day and night, for which we have successfully completed additional training,” he says.