Noise Modulated Ground Penetrating Radar

GPR has been used for road pavement analysis, but to a limited extent. This has often been restricted to single channel GPRs, and at lower than traffic speeds, making traffic control necessary. The technology needed to be extensively redeveloped for it to become a useful tool for road authorities. Radar Portal Systems has achieved this through the development of its patented NM-GPR.

NM-GPR is a proprietary and patented design of radar which is different to previous types of GPR used for road and pavement analysis. Unlike step-frequency and impulse radar our NM-GPR provides the user with 3D subsurface images at high speed. See our demo clip and Portal 4D images.

The current RoadScout uses this leading edge high speed and high precision ultra-wideband 3D ground penetrating radar (GPR) system, to image the subsurface of roads and highways. The system is fitted with 24 simultaneous GPR units, which scans a 2.5-meter wide section of road, down to a depth of 1.2 meters at speeds of up to 100km/h. With a scanning grid of 6cm x 6cm the GPR produces a high definition image of the subsurface, which can be viewed as a 3D iso-surface or arbitrary slicing. The data is geo-located through a combination of GPS, inertial and encoder sensors. The result is a complete understanding of the pavement structure, including layer depths, the location of changes in construction, areas of high moisture content (including water filled cracks), location of utilities and other subsurface anomalies.

Using GPR to build better roads

Ground Penetrating Radar (GPR) is a technique where an ultra wideband electromagnetic signal is transmitted into the ground and the returned reflections measured to determine the presence of subsurface objects or features. There are many applications where GPR has been demonstrated to be useful, including utility detection, road pavement profiling, concrete rebar detection, archaeology, locating broken water pipes and many more (anywhere detection of shallow subterranean targets is required).

The RoadScout has many features not available in competitive GPR systems, and brings the use of GPR into the 21st Century. GPR has now become a useful and practical tool for road authorities.

For road pavements, GPR is used for:

• Pavement layer depths – asphalt, granular, and concrete.
• “As constructed” information and pavement changes / homogeneity.
• Locating:
  
  • Services
  • Anomalies – e.g. voiding, rock, and buried objects.
  • Moisture ingress and inclusions
  • Calibrating deflection measurements to determine pavement material properties.
  

GPR Output Examples

Example of Change in Construction