2023 - Australia - Austroads Road Deterioration Model Update: Roughness

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 roughness RD model.

The roughness RD model documented in this report was based on a mechanistic-deterministic approach using a multi-variate non‑linear regression analysis. The roughness RD model uses cumulative roughness as the dependent variable for thinly surfaced flexible unbound granular pavements based on the Austroads LTPP/LTPPM dataset collected from 1994 to 2018. The roughness RD model may need some calibration to suit locally observed roughness conditions.

The model also has the capacity to be adapted to surface maintenance treatments other than double/double seals to determine their impact on cumulative roughness by using relative performance factors for surface maintenance treatments. The model was validated using an independent dataset.