Relationship between Foreign Object Debris, Roughness, and Friction

Abstract

The Federal Aviation Administration (FAA) is developing new design procedures to extend airport pavement life beyond 20 years based on the concept of serviceability: the measure of how well a pavement fulfills user expectations. A key element is a new distress megaindex called serviceability level (SL) whose components represent independent aspects of airport pavement serviceability: low foreign object damage (FOD) potential, low skid potential, and smoothness. This research validates the assumption of independence previously used to develop a probability-based form for SL. Independence greatly simplifies the mathematics of the new form, in particular, the ability to decompose a pavement condition model into multiple relatively simple submodels. Friction is shown to not correlate to the other two components. FOD and roughness are conditionally independent with a latent variable of crack and spall density. Conditional independence means the proposed SL formulation is generally valid but requires that FOD and roughness measurements or predictions be made at the same time using the same assumptions.