Austroads Road Deterioration Model Update: Rutting

This report documents a project designed to update the current Austroads road deterioration (RD) models using the long-term pavement performance and long-term pavement performance maintenance (LTPP/LTPPM) dataset and other data available, such as the traffic speed deflectometer (TSD) datasets, to improve these models' explanatory power. A proof-of-concept approach based on using the available TSD datasets undertaken early in the project determined that these datasets were not appropriate at this stage for developing an updated rutting RD model. The rutting RD model was based on a mechanistic-deterministic approach using a multi-variate non-linear regression analysis. The rutting RD model uses cumulative rutting as the dependent variable for thinly surfaced flexible unbound granular pavements using the Austroads LTPP/LTPPM dataset collected from 1994 to 2018. The rutting RD model may need some calibration to suit locally observed rutting conditions using a calibration coefficient, Kr. The model also has the capacity to be adapted to surface maintenance treatments other than double/double seals to determine their impact on cumulative rutting by using relative performance factors for surface maintenance treatments. The model was validated using an independent dataset. Austroads makes the report available on its web site at https://austroads.com.au/publications/pavement/ap-t370-23