Road testing technology reaching underground

01 Dec, 2021

As part of ongoing improvement of Kaipara’s unsealed roading network, the Northland Transportation Alliance is using Ground Penetrating Radar (GPR) to confirm pavement thickness safely and rapidly across the district.

The road pavement is the structural layer that provides the strength and shape for the road. NTA Maintenance Lead Bernard Petersen says the technology is used to test depth and moisture in the road’s base.

“We attached the GPR unit to the back of a moving vehicle. As we slowly drive between 30 and 40kmh, it sends electromagnetic waves into the ground every 100mm from each of four antennas.”

Consigned to the Unsealed Road Improvements Project led by Kaipara District Council, the technology has been tested on 108 roads, totalling 259km during October and Petersen notes it has had excellent results.

“We can use this technology to quickly see how thick the pavement is and identify weak spots. It’s much faster and cheaper than traditional methods, where we had to dig a test pit every 100 metres. This information will speed up pavement designs for the next few years of unsealed road reconstructions,” he said.

GPR has proven successful on roading projects around the world and can remain effective at speeds up to 100kph.

“While the current testing round was wrapped up within a week, you can expect to see more use of this technology in the Kaipara in future years, as we strive to better understand our unsealed network. This tech is helping to more confidently programme work requirements with the right treatment, at the right time.”

GPR is currently being fine-tuned on Kaipara roads to confirm pavement thickness. PHOTO/SUPPLIED