Drones trialled for the inspection of large railway structures

The LNE&EM route Structures asset management team is trialling the use of unmanned aerial vehicles (UAVs) to inspect large structures in a safer and more cost efficient way.
The vehicles, commonly known as drones, are being used to get a closer look at five arch viaducts on the route, including the Grade 1 listed, 28-span Royal Border Bridge in Berwick-upon-Tweed, Northumberland.

Since 2017 the Structures team has been working alongside AECOM consulting engineers, Network Rail’s Air Operations team and Cyberhawk – a company that operates UAVs – to carry out the inspections, gaining a panoramic bird’s eye view of the structures.

With an increasing number of structural assessments, including of many arch viaducts, the team had identified a need for a more efficient inspection method to supplement the more traditional access techniques typically used.

Terry Donaldson, scheme project manager at Network Rail, said: “UAVs are commonly used in other industries such as oil and utilities to inspect their structures, such as pylons and oil rigs. We thought ‘why not try them out?’

“As well as being cost effective, this innovation has reduced the need for possessions, track access and roped access, reducing safety risk.

“The quality of the information our asset engineers have received has also been much better than what can normally be produced with standard inspection techniques.”

Quality information

The high-definition images captured by the UAVs will be examined by asset managers. Previously, photographs would be taken by the engineer as they carried out the inspection at height – abseiling down the structure, often in the dark and poor weather – with views limited to where the person could reach and see.

Nick Tedstone, professional head of Structures, Network Rail, said: “Increased use of UAVs can provide our engineers with higher levels of quality information to allow them to make the best possible decisions on the future of our structures assets.”

As well as delivering a more comprehensive 360 degree view of the structures, in daylight and showing all the defects clearly, the UAV images are being stitched together with photogrammetry to create high quality 2D elevations, 3D models and also cloud point surveys (avoiding the need for a separate dimensional survey).

Sam De’Ath, asset engineer, Structures, Network Rail, said: “It seemed a good idea for us to start unleashing UAVs on some of our bridges. They’ve turned out to be an excellent tool for the inspection of arch viaducts in particular, such that further UAV inspections are now being planned.

“Aerial inspections can’t fully replace an engineer with a hammer – some degree of tactile inspection is still needed – but we’re now able to use the better imagery to find areas of concern and target those.”

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