Pavement analysis and design: historical perspective

The past pavement design approaches were mostly empirical in nature and were based on experience.

• CBR method of pavement design is one of the earlier pavement design approach developed during 1928-29 (Ullidtz 1986). In this method the thickness design charts are developed (based on observation of number of sections), with reference to the subgrade CBR value for the most critical moisture condition. In 1940 this method was adopted by the U.S. Corps of Engineers for design of airfield pavements (Horonjeff and Mckelvey 1983). It is interesting to note that the design initially did not involve traffic as a parameter, which was introduced later as a correction factor. The method was further improved by considering the CBR values of the individual layers and thereby individual layer thicknesses are obtained. In some other approach, Hveem resistance value of pavement materials is used instead of CBR value.
• Another pavement design approach considers aspect of bearing capacity of the individual layers, and the design is finalized in such a way that the bearing stress does not exceed the bearing capacity of the individual layers. This method was first proposed by Barbar in 1946, and is still in use (TRH4 1996, deBruin et al. 2002), however this method does not seem to account for traffic repetitions.
• Another approach recommends limiting recoverable deflection as the criterion for pavement design (Huang 1993). Failure theories suggest that the failure of a structure is due to excess stress or strain, thus, deflection may not be attributed as basic pavement design criteria.

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