avement structure data on the CPATT (Centre for Pavement and Transportation Technologies) test road at the University of Waterloo was acquired at speeds of 40 to 80 km/h (30 to 50 mph). The SmartTrailer configuration enables rapid acquisition of surface coupled GPR. All data were collected using a vehicle odometer at a user-defined spatial interval. DMI and GPS provide precise positioning.
Using the integrated GPS data, the CPATT test road is marked in red and yellow on the Google Earth map below.
The below figure shows a 100 m section of data (yellow line in the Google Earth map above). The section shows asphalt over granular, above the subgrade. The asphalt-granular and granular-subgrade boundaries are clearly visible. A short section of thicker asphalt (Asphalt 2) is evident between 360 m and 364 m.
The data in the cross-section are a subset of the full 700 m CPATT test road. RoadMap automated horizon analysis generated for the full test road are shown above.
GPR travel times were converted to depth by calculating velocities from feature responses in the data itself, and by correlating with core thickness data. An example of a layer thickness summary report is shown in the table below.
LAYERS | AVERAGE THICKNESS (mm) | STANDARD DEVIATION (mm) | NUMBER OF MEASUREMENTS |
---|---|---|---|
Asphalt 1 | 97 | 5 | 3376 |
Asphalt 2(360–364 m) | 142 | 3 | 18 |
Granular | 592 | 67 | 3146 |