Structural number determined with the falling weight deflectometer and used as benchmark methodology

Emile Horak, Arno Hefer, James Maina, Steve Emery


The modified or adjusted structural number (SNC or SNP) is widely used to define the structural capacities of various flexible pavements. Viable correlations between either SNP or SNC and a variety of falling weight deflectometer (FWD) deflection bowl measuring points or parameters exist. Whilst historical use of maximum deflection continues, a large portion of the inherent structural information in the rest of the deflection bowl goes underutilised. The paper presents and validates a single relationship of parameters, representing the full deflection bowl, and effective adjusted structural number (SNPeff). SNP and the structural condition index (SCI) are widely used on network and preliminary project level investigations, but cannot identify origin of the distresses. The complementary use of a deflection bowl parameter benchmark analysis can greatly enhance such investigations. In this paper the use of deflection bowl derived SNPeff, SCI complemented with deflection bowl parameter benchmark analysis is demonstrated with a case study.


Modified and Adjusted Structural Number; flexible pavements; falling weight deflectometer; deflection bowl parameters; benchmark analysis; structural condition index

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