Spectral and 3D imaging to be integrated into single device to assess structural integrity

The team from Nottingham Trent University and Opus International Consultants, a global infrastructure consultancy, expect the device to accurately verify the integrity of such structures – including ageing bridges – from a distance of up to 100m.

James Hulme, part of Opus International Consultants’ UK Leadership Team, said: “We are always looking for new technologies which offer cost-effective solutions to safely defer expensive upgrades or replacements that may not actually be required.”

The project will build on previous Nottingham Trent University research that saw the development of a remote spectral imaging system that reveals the composition and degradation of paints in large-scale wall paintings. Red ochre – a natural earth pigment used to make paint – is made up of the same chemical ingredient as rust, namely iron oxide.

The project could potentially save significant surveying costs and remove the need for potentially dangerous inspections. It will also help to inform decisions about when to repair or decommission structures, including pylons, culverts, station canopies, roof structures and tunnel linings.

The three-year project involves the creation of a remote imaging system that simultaneously performs 3D and spectral imaging, which will provide information about the physical and chemical characteristics of the structure.

The so-called ‘RustScan’ instrument and accompanying ‘RustDetect’ software – which will be used via hand-held or tripod-mounted cameras or drones – will be able to generate detailed data regarding surface blistering and corrosion.

Prof Haida Liang, head of the Imaging & Sensing for Archaeology, Art History & Conservation research group at Nottingham Trent University told The Engineer that the device will be able to scan as much of a structure’s surface as necessary and that proven algorithms – already applied to large wall paintings - will automatically stitch images together. She added that current image processing methods would be employed to automatically classify the regions of corrosion via a 3D model of a structure's condition.

“Remote simultaneous 3D and spectral imaging will provide direct identification of surface rust and corrosion,” she said. “The technology will also be able to provide a time-specific record of the condition of the bridge for future comparison with later scans – in addition to assisting in the development of an appropriate maintenance programme for the bridge.”