Design of overlays based on pavement condition, roughness, and deflections : part 1 : tentative method for overlay design based on visual pavement distress.

3829287PDFTech ReportVHTRC 78-R24VirginiaVirginia Transportation Research CouncilVaswani, Nari KVirginia Highway & Transportation Research CouncilUnited States. Federal Highway AdministrationUS Transportation CollectionData collected on 111 interstate highway projects in Virginia were analyzed by multi-regression analysis and the rating coefficient for each type of distress determined. By this means, the total pavement distress and, hence, the maintenance rating of each pavement was obtained. The types of distress that were found to influence the maintenance rating were longitudinal cracking, alligator cracking, rutting pushing, raveling, and patching. Then, a method for designing the required thickness of an overlay was developed based on taking the thickness equivalency of an asphaltic concrete overlay in Virginia as equal to 0.5 (the thickness equivalency of an asphaltic concrete for new construction is 1.0) and the overlay thickness as a function of the ratio of the traffic, in terms of 18-kip (8,160 kg) equivalents, carried by the pavement before the overlay to the traffic it would carry after the overlay, depending on the durability of the asphaltic mix. This design method does not require the use of a deflection measuring device