Crossfall and Vertical/Horizontal Curvature Measures

The PaveScout system can measure road cross-fall as well as vertical or horizontal curvature

Through a combination of Inertial Measurement Unit (IMU) and GPS measurements, the PaveScout system can measure road cross-fall as well as vertical or horizontal curvature from the vehicle travel path. The difference to other commercial systems is the accuracy of this technology and its ability to self-correct. Unlike other systems where often a different scanning method is required to obtain cross-fall (where the vehicle performs loops to correct for angle drift), the PaveScout system can collect these measures when doing normal scanning, due to the higher accuracy IMU/GPS systems utilized. The result is that RPS data has cross-fall. When very high accuracy cross-fall is required, such as for rehabilitation surveys then a GPS reference station should be used to allow for better height correction.

The laser data can be displayed as either a transverse profile of the road or as a thermal colour-map. In the image below a transverse profile is shown. From this image, the rut depth or texture depth can be graphically displayed.

Curvature graph

Transverse laser profile showing the 2048 points across the road surface. This can be displayed either with or without texture. For rutting measurements, the road surface texture is removed allowing for more accurate assessment of rut depth. For texture measurements the surface texture is used.

The image below shows the laser data displayed as a thermal height map. Within the image cracking (with spalling), and the raised patch are quite obvious. The height of the raised patch can be determined by noting that the colour change is from blue/purple to red, which corresponds to a positive rise of around 10mm.

A cyclic colourmap is used to represent the height of the pavement at any one point in time.  The colourmap wraps every 30mm of height.  As a result, the colourmap is useful to determine any differential settlement within the surface.

Curvature colourkey

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