A computerized procedure, loadrate, version 2.0, Has been developed by the texas transportation institute (tti) for the texas state department of highways and public transportation (sdhpt) to evaluate the structural adequacy of light pavement structures, specially for the purpose of load zoning. The loadrate program uses data obtained from the dynaflect or the falling weight deflectometer (fwd) to evaluate pavement condition. A simple mechanistic procedure is used to calculate rut depth, given the number of passes of a wheel load or a multiple-axled vehicle, or vice versa. When supplied with estimated traffic, the procedure can be used to predict the remaining life of pavement sections and to provide an estimate of pavement condition. Loadrate can make temperature and moisture corrections for the base course modulus. It can also estimate the effects of seasonal variations of the base course moduli on the life of the pavement. Significant improvements of version 2.0 Are the incorporation of a nonlinear relationship for modulus versus deviator stress for sandy subgrades and the reconstruction of the two data bases used in the program. The rut depth can be better determined from these improvements. In the case studies, the strength of the pavement at the edgeis weaker than the strength of the pavement in the outer wheel path. A paved shoulder not only prevents water penetration into the road bed, but also provides some lateral support to maintain pavement strength. This paper appears in transportation research record no. 1260, Measurement of pavement surface condition 1990.
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