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In New Zealand, premature failure of low volume, low strength state highways and local authority roads has sometimes occurred due to significant changes in heavy commercial vehicle traffic. Current New Zealand pavement deterioration models (eg NZ-dTIMS and HDM) were not designed to simulate these sudden increases in traffic loading and their effects over short distances.

The NZ-dTIMS and HDM models along with other pavement distress models were investigated to establish their suitability for modelling extreme variations in traffic loading. The relationships between measurements of structural strength and pavement condition data were investigated for selected pavements. The sensitivities of some pavement deterioration and pavement distress models to extreme traffic loading were also investigated.

The key finding was that the extreme traffic loading must be sustained for a lengthy duration to show up in RAMM pavement condition and reactive maintenance cost data. This observation indicates that employing pavement deterioration models may be the preferable analysis route for evaluating the effects of extreme traffic loading rather than analysing historical RAMM data. To enable this, the available pavement deterioration models need to be improved to better model observed localised pavement damage that results from extreme traffic loading, particularly edge break.

Keywords: cracking, extreme traffic loading, pavement deterioration models, roughness, rutting, structural number