Topographic Surveys Using UAV:

Mott MacDonald Bentley

Topographic surveys are widely used across the civil engineering and construction industries – on sites where it’s important to get a clear understanding of shape and contour. However, the traditional approach – using teams of surveyors to locate hundreds or thousands of points on a chart – presents a number of challenges that modern UAVs can address.

Site access is a common obstacle to the speedy completion of a survey. Those visiting a site may have to contend with restricted vehicular access, physical barriers such as fencing and hedges, landowner permissions and even hazards such as deep mud or steep slopes. By contrast, a UAV can make repeated passes over a site without obstruction, enabling surveys to be completed many times faster than the usual manual approach.

Modern software can be used in conjunction with high resolution photography to generate a detailed 3D model with accurate contour mapping. Importantly, these contours are based not a few thousand individually measured points but millions. The resulting model delivers far more detail than any conventionally produced drawing and, when the original photos are set as a separate layer beneath it, the result provides engineers and planners with additional visual cues, context and a clearer understanding of any uncharted features.

Typically, the UAV survey process will be in the region of four times faster than a manual survey and will yield corresponding cost savings. However, ground conditions will largely dictate the speed and, in some circumstances, projects may be completed up to ten times more quickly.

However, UAV-based surveys cannot and should not be conducted completely independently from a surveyor. On a middle-sized site, perhaps a dozen control points will need to be located and marked on the ground for reference. Obviously, however, setting just twelve points rather than thousands represents a significant time saving and quickly frees survey staff to move on to other work.

SUAVE has recently undertaken topographic surveys of the terrain surrounding a reservoir and, separately, an area around a broken water main. With subsequent processing, which SUAVE can deliver, the survey data from projects such as these can be plugged into client systems to provide an accurate digital record of the site. For more information about topographic surveys, please contact us.

Building Survey: 24 Mount St., Manchester

Kier

City centre building inspections present their own special challenges. Busy roads and pavements, together with the close proximity of other buildings, mean that erecting scaffolding or mast-climbers can be inconvenient and obstructive; sometimes impossible. In such circumstances, the use of UAVs can represent a safe, quick and low cost alternative.

Manchester’s 24 Mount Street (formerly ‘London Scottish House’) is an excellent example. A five-storey structure originally built in 1973, it stands next door to the Grade 2-listed Midland Hotel and across the road from the Manchester Central exhibition centre. In August 2016, its owner, FORE Partnership, was granted planning consent for a partial demolition and refurbishment project that would see the creation of 100,000 sq ft of grade A space, a green wall and a rooftop terrace.

In preparation for the works, the contractor commissioned SUAVE to carry out a detailed aerial inspection of the roof and topmost level. In addition to high resolution photography, the deliverables included a point cloud and a 3D model that architects and engineers could subsequently use in their planning.

Given the restricted access (including one-way streets on two sides) and the building’s unusual L-shape, a UAV-based survey provided to be the ideal solution. On the basis of a single half-day visit, SUAVE  completed the required photographs and telemetry, which it then processed and provided in a variety of forms, including the required point cloud and 3D model.

Construction work on the £13m scheme is due to continue until towards the end of this year. The finished property will have seven storeys with retail units on its two lowest floors. There will be modern office space above, together with a rooftop terrace to be used for meetings and social gatherings. An noteworthy design feature will be a ‘green wall’ on its southern elevation, in which occupants will be encouraged to grow fruit, vegetables and other plants.

For more details of our roof inspection services, please contact us or click on any of the images above. Alternatively, please visit the construction section of our website.

Archaeological Survey: Grimsby

Wessex Archaeology for Murphy

55 miles off the coast of Grimsby, Hornsea Project Two is creating the world’s largest offshore wind-farm. The multibillion-pound scheme will see the installation of 300 turbines over an area five times the size of the city of Hull. Funded by a Danish energy company, the site will eventually deliver clean, sustainable power to around 1.8 million British homes.

Bringing that power ashore, of course, requires a very substantial cable and the route that its 1.5m trench will take across the landscape passes through a number of areas of archaeological interest. Surveying those sites is where SUAVE comes in.

The cable itself will be laid by infrastructure specialist J. Murphy & Sons and as part of the contract, it is working with Wessex Archaeology to identify and evaluate any historically important sites and features. The work so far has required the creation of several very large trenches – some measuring more than 300m by 40m – and Wessex Archaeology asked SUAVE to help produce a detailed photographic record.

We have made two day-long visits to survey the trenches at the point of their completion. The most recent of these was in February 2017. Their aim is to produce detailed survey data before the construction work continues and the archaeology is hidden once again.

The results of our visits to date can be seen in our online gallery.

Structural Survey Video

Video Thumb Structural surveys are becoming an increasingly important part of our work. To showcase our capabilities in this field, we have launched a new video. It shows our work on everything from ancient monuments to football stadiums.

Structural Survey: Canterbury Cathedral

Downland Partnership

Founded in 597 and rebuilt in 1077, Canterbury Cathedral is one of Britain’s oldest and best known ecclesiastical buildings. It is home to the Archbishop of Canterbury, it was the site of Thomas Becket’s murder, and it features in Geoffrey Chaucer’s Canterbury Tales. By any standards, the Cathedral is exceptionally rich in history and, indeed, it is part of a recognised World Heritage site. Continue reading “Structural Survey: Canterbury Cathedral”

Aerial Survey of the Coupland Buildings

University of Manchester

The University of Manchester owns and manages many historic listed buildings and these include a notable collection on Coupland Street, where SUAVE was recently asked to conduct an extensive roof survey. Coupland 3, for example, was built in 1891 as part of the School of Medicine and, today, it’s a striking structure of brickwork, decorative masonry and spires. Continue reading “Aerial Survey of the Coupland Buildings”