Device detects and fills tarmac cracks as it moves along road

US researchers have developed a system that automatically detects and seals tarmac cracks as it moves along a road.

The prototype trailer device, built by engineers at the Georgia Tech Research Institute (GTRI), is able to detect and fill cracks as small as 0.125in (3.2mm) over an area of road around 1ft (30cm) wide from a vehicle moving at 3mph (5km/h).

If the system can be scaled up to cover the width of an entire lane, the system could reduce traffic delays by allowing roads to be repaired without the use of static roadworks and postpone the need for full resurfacing.

The road scanner works by illuminating the surface using LED lights of two different colours pointing parallel and perpendicular to the road and then taking two pictures of it using a stereo camera.

Software analyses the resulting 3D image to locate any cracks and this guides the system to deposit sealant in a similar way to a printer.

Cracks parallel to the road direction are filled using a single dispensing nozzle that can move over the road surface. Perpendicular cracks are sealed by a system of 12 nozzles spaced evenly across the trailer.

The software was trained with more than 100,000 images, increasing its ability to correctly identify cracks to an 83 per cent success rate.

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But the detection algorithm would need to be improved further in order to scale up the system for commercial use, according to research leader Jonathan Holmes.

‘Our crack-detection algorithm was limited because we used a vision-based system, which was confounded by regions of high contrast caused by features other than pavement cracks, including dark stains in the pavement, lane stripes, raised-pavement markers, crack sealant and debris,’ he said in a statement.

‘A full-scale system may require a fusion of multiple imaging sensors, such as a 3D laser scanning system.’

Holmes added that changes in the way the sealant was supplied to the longitudinal and transverse distribution systems would also be needed to develop a full-scale system.