Road Inspection
High Speed 3d Road and Surveys using 3d-Radar GPR Equipment
High density GPR data of the entire width of roadway is critical to fully understand and assess the condition of roads and bridges. Using traditional methods, it can be a time consuming, expensive and dangerous job to fully acquire high resolution subsurface imagery. With traditional, impulse based GPR systems, full coverage of a lane requires multiple passes at slow speeds which entails road closures during the survey or at a minimum, traffic control. To get a complete picture of the subsurface at a variety of depths, multiple antennas might be employed which requires more equipment, possibly multiple passes and more time post-processing to fuse the data collected and produce a report. However 3d-Radar offers a better way to quickly capture, process and visualize high density subsurface data.
1.8 Meter antenna with optional trailer surveying a bridge deck
The 3d-Radar GeoScope™ Mk IV coupled to a 3d-Radar VX-Series multi-channel antenna can capture a lane width of data in three dimensions at highway speeds in a single pass, while maintaining high resolution and good depth penetration. Step frequency GPR makes this possible by collecting both data at low frequencies and then stepping up to very high frequencies which captures the entire subsurface with a single radar and antenna array in one pass. Once collected, this data can be quickly analyzed in the field using 3dr-Examiner, 3d-Radar’s processing and display software suite. Condition assessments can be done on the spot and in high-definition, enabling even finer detail surveys of selected areas to be performed while the equipment is in the area, or simply stored for further interrogation and reporting after the once back in the lab.
Bridge Decks can also be analyzed in detail using this same technology. The VX-Series multi-channel antenna has elements spacing of only 7.5cm. By sampling every one or two centimeters, high density data is acquired, with which rebars can be clearly seen in three dimensions, both during acquisition itself and later by using 3dr-Examiner.
3d GPR data from a bridge deck – Top image shows a horizontal slice of data, with rebars visible. Bottom image shows the same data, with rebars.
By utilizing the optional common midpoint feature inherent to the GeoScope Mk IV and the antennas, depth calculation without coring can be performed. Additionally, layer thickness reporting can be done across the entire swath width up to 10 feet. Calculating layer thicknesses across an entire lane with enables detailed condition assessments to be performed, factoring in wheel – loads, crowns, frost heaves and other features which might be missed with a more coarse grained assessment.
- Wide swath widths cover up to a lane width in a single pass- 100% coverage and analysis provides greater confidence in the survey
- Surveys with high degree of detail at highway speeds – Less time in the field while collecting more data
- Deeper depths without compromise in resolution – Issues near the surface along with deeper coverage provides the entire
- Interleaved Common Midpoint(CMP) scan pattern – No coring necessary to calculate depths and layer thicknesses
- Advanced data processing and visualization software – Minimize time spent analyzing data and producing reports
- Lane closures and traffic control requirements are kept to a minimum – Safer working conditions and happier motorists
