Figure 1 shows the cumulative distribution function (CDF) of the absolute
differences for both the base and subgrade pressure cells utilized at the Test Track. This
analysis contains data from all ten test sections that were tested with the FWD. Only
zero offset loading data was used for this analysis. This means that the FWD load was
directly above the embedded pressure cell and there was no transverse or longitudinal
offset of the FWD load from the gauge position.