Mechanistic-empirical pavement design methods for flexible pavements are based on the assumption that the pavement life is inversely proportional to the magnitude of the traffic-induced pavement strains. These strains vary with the stiffness of the asphalt layer, which in turn varies with temperature. Because these relationships are nonlinear, the additional pavement life consumed at higher-than-average temperatures is not offset by savings at lower-than-average temperatures. As a result, whenever average pavement temperatures are used to determine the asphalt stiffness, pavement life is overestimated. Using hourly pavement temperature data from an instrumented pavement site in Tennessee, the effects of temperature averaging on predicted pavement life are examined and it is shown, for a typical full-depth asphalt pavement section supported by subgrade soils of different strengths, that pavement life can be overestimated by 50% to 75% if the temperatures are aggregated into monthly averages. It is also shown that even hourly average temperatures can produce errors if the hourly distribution of truck traffic is not taken into account.
Abstract