Analysis of Climate Effects on Performance of Unpaved Roads

Abstract

The performance of unpaved roads is strongly dependent upon the moisture content within the roadway profile. Unfortunately, there are no analytical models currently available for quantitatively predicting the influence of depth and time‐dependent moisture distribution upon this performance. Existing procedures rely on laboratory or field tests, or indirect empirical correlations, to define the strength characteristics of each roadway layer in terms of a single, generally conservative value intended to reflect worst‐case climatic conditions. This paper presents a rational methodology for analyzing the effects of site‐specific rainfall and evaporation history upon the performance of unpaved roads. The methodology consists of a predictive model for weather‐induced, soil‐moisture changes over time; relationships between soil moisture, compaction level, and strength for a variety of typical roadway soils; and a damage analysis model tailored to low‐volume unpaved roads. The capabilities of the proposed methodology are demonstrated through a numerical example. Performance predictions from the proposed methodology are comparable to those from more conventional approaches.