Abstract
The paper addresses an interesting issue: providing a means of selecting routine-maintenance options based on the rough ness-progression profiles. The discusser discusses some short comings relating to the roughness modeling and maintenance effectiveness indices. In the paper, maintenance effect is modeled in terms of roughness as a function of age, traffic loading, and environ ment based on field data. Modeling roughness is much more complex than presented in the paper; moreover, some im portant variables that determine the roughness of a pavement are not included. In capturing all the contributing mecha nisms, the structured empirical approach includes the inter active terms of structural, surface-defect, and environmental effects in which roughness is modeled as a function of (I) structural deformation (function of modified structural num ber, traffic loading, etc.); (2) surface defects (function of changes in cracking, patching, and potholing); and (3) en vironmental and nontraffic-related mechanisms (function of pavement environment, time or age, and roughness) (Pater son 1987). In the more common generalized-structural-per formance model, roughness is expressed as a function only of traffic loading, pavement structural number, age, and en vironment. The surface-distress component is excluded. In either case, the structural capacity of the pavement and the supporting subgrade indicated by the modified structural number is one of the independent variables, because it influ ences pavement performance to a considerable extent. The authors presented a model that is similar to the gen eralized structural model but excludes the modified structural number of the pavement. Although it is stated that all pave ment sections used in the analysis are of the same type (flex ible pavement), it is not explained that the structure of the pavements (the thicknesses of and material types for the var cious pavement layers) and the subgrade conditions in all the
Published Version
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