Seasonal Variation In Flexible Pavement Deflections

Abstract

A mathematical model is formulated to relate flexible pavement deflections to single-axle load, thickness of pavement components, and time (or season of the year). Plotting creep speed deflection versus time for the AASHO Road Test data reveals significantly higher deflections in the spring than in the winter. This behavioral pattern is described reasonably well by a sine wave of constant amplitude oscillating about a displaced horizontal base line. The assumptions of constant amplitude and horizontal base line are substantiated to some degree by data taken over a ten year period from seven highways in Maryland, but they are subject to modification as more data becomes available. The amplitude of the wave and level of the base line are then determined as functions of the thickness index and applied single-axle load, and correlation plots are given to indicate the reliability of the resulting mathematical model in predicting measured deflections.