FWD (Points)

The falling weight deflectometer (FWD) is a non-destructive testing (NDT) device used to evaluate pavement structural condition. The FWD imparts a load of known magnitude to the pavement, and the resulting deflections of the pavement are measured.

  • D1 Average

    The D1 Average is the maximum deflections as measured by the FWD sensor in the centre of the load plate, averaged over the length of a pavement segment. The maximum deflection (D1) gives a good indication of the overall structural condition and load-bearing capacity of the pavement.

    ../../../../_images/FWD_Points_d1.png

  • D7

    The D7 sensor measures the deflection at 1800 mm from the centre of the load plate. The SCI Average is the SCI values averaged over the length of a pavement segment and gives a good indication of the condition the subgrade layer.

    ../../../../_images/FWD_Points_d7.png

  • SCI Average

    The Surface Curvature Index (SCI) is calculated as the difference between the D1 sensor reading and the D2 sensor reading at 300 mm from the centre of the load plate. The SCI Average is the SCI values averaged over the length of a pavement segment and gives a good indication of the condition of the upper pavement layers.

    ../../../../_images/FWD_sci.png

  • D1 Design

    The D1 design is the D1 deflection at the location within a segment that most closely matches the 85th percentile of all D1 results from that segment and is used for design purposes as being representative of that particular segment.

  • Rehab Type

    Rehab type is the type of pavement rehabilitation recommended based on the FWD testing and analysis.

  • Rehab Thickness

    Rehab thickness refers to the thicknesses of various pavement layer materials specified in the pavement rehabilitation. This can include overlay material (e.g. bituminous, granular) thicknesses as well as depths of existing pavement material to be removed.

  • Residual Life

    The residual life of a pavement structure can be defined as the life remaining in terms of millions of standard axles before failure.