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This report details the findings from research conducted on the Long-Term Pavement Performance Programme (LTPP) and on the Transit New Zealand CAPTIF programme for accelerated pavement testing. The research was aimed at delivering a complete new model format to predict rut progression on New Zealand roads. It was based on earlier findings that suggested some limitations with the current approach using the World Bank’s HDM rutting models.

A three-stage modelling approach is recommended:

• Firstly, a simpler model is proposed to predict the initial rutting or densification.
• Average progression rates are proposed for the annual increase of rutting during the normal life of the pavement since no satisfactory model could yield any results which were more accurate.
• Lastly, a probabilistic model is proposed to predict the probability or risk of a pavement undergoing accelerated rut progression caused by weak layers or overloading.

One benefit that the new proposed model promises is its simplistic format which makes it easy to adopt into a modelling system. Another is it is based on improved accurate pavement condition data. Further work in this area is recommended, mostly on the practical implications of these research findings, and on developing remaining models based on the LTPP programme and CAPTIF experiments.

Keywords: CAPTIF, failure, HDM model, LTPP, model development, New Zealand, pavement deterioration, pavement failure, pavement models, pavement strength, pavements, rut progression, rutting