RPS uses high speed profiling to measure rutting, texture depth, roughness and form 3D laser maps of the road surface.
The system uses a careful calibration procedure to minimized errors, resulting in highly accurate results.
When looking at the images, what needs to be understood is how to determine if a change in colour is indicating a dropped or risen pavement condition. This can be determined by finding the two colours on the colourmap, and then finding the closest distance between those top points on the colourmap and then determining if this is either in the positive or negative height change direction. When doing this you must remember that the colourmap is cyclic. For example:
A 10mm raise would be a change from blue to red, or a change from green to blue or a change from red to green. A 10mm drop would be a change from red to blue, a change from blue to green or a change from green to red. Figures 2 and 3 show this procedure in practice. Please note that in the images, the crossfall of the road has been removed to improve the ability to detect the differential movement between the slabs.