A mechanistic design procedure was adopted by Transit New Zealand for rehabilitation projects on New Zealand roads. Deflection testing and back-analysis of the deflection bowl induced by a standard wheel load provided the principal parameters for mechanistic design.
Research was initiated in 1996 to study about 30 pavement sections, most being of unbound granular construction together with a small number of sections containing either thin asphaltic surfacing or cement-stabilised basecourse. A wide range of subgrade types were included and there were also comparative studies of conditions before and after rehabilitation treatment, to verify the mechanistic designs.
This, the first of two reports for this project, is intended to complement existing documents, in particular the AUSTROADS Pavement Design Guide and its New Zealand Supplement for mechanistic analysis. The objective is to provide New Zealand practitioners with concepts and parameters applicable to local conditions, as well as to provide a more detailed appreciation of key principles that are applied in mechanistic analysis, quality assurance for both the field data and the design results is addressed. A set of examples and results for different overlay methods is also supplied to show how to obtain insight into pavement behaviour, to examine distress mechanisms, and to select the most appropriate rehabilitation treatment.