2004 - Australia HDM Sealed Deterioration Models

Road agencies in Australia are adapting HDM-4 technology to the strategic management of their road
networks. There is a need to develop HDM-4 technology road deterioration (RD) models for sealed granular
pavements as they comprise 95% of Australia’s rural arterial roads. Austroads has funded ARRB Transport
Research (ARRB) since 1994 to adapt HDM-4 technology to Australian conditions.
Since 1994 ARRB has monitored long term pavement performance (LTPP) sites to observe road
deterioration with traffic loading, climate and pavement type. From 1998 onwards, ARRB has also
monitored the influence of maintenance on sealed granular pavement performance using long term
pavement performance maintenance (LTPPM) sites on Australia’s arterial roads, specifically varying surface
maintenance treatments at each site. In addition, ARRB, in an independent consulting capacity, has
performed field data-driven RD model calibrations for a number of States.
Accelerated load testing (ALT) of experimental sealed granular pavements commenced in 1999 to quantify
the influence of maintenance on relative pavement performance, under controlled conditions of loading,
climate and maintenance. In 2003 ALT was used to quantify the influence of increased axle mass loading
on pavement deterioration.
Historical Australian seal life and binder hardening data was available to ARRB to develop a refined binder
hardening model using variables for environmental conditions, elapsed time, binder characteristics and the
nominal seal size. This refined model, in conjunction with an existing distress viscosity model, allowed the
development of an explicit seal life model to predict the expected life of different nominal seal sizes in
different climates throughout Australia.
This paper presents the current state-of-the-art characteristics, by means of re-calibrated default coefficients,
for the RD models for roughness and rutting progression which were shown to vary with the environment
and surface maintenance treatments. The RD model re-calibration used the observational data from the
LTPP and LTPPM sites in conjunction with the relative performance factors estimated for various surface
maintenance treatments from the ALT data. The current imitations of these revised models with the above
sealed granular pavement data are stated, including those for the seal life model. As a result, the RD
models are more responsive to changes in maintenance under a range of Australian climatic conditions.
It was not possible to predict the impact of surface maintenance treatments, time and traffic on the structural
deterioration of sealed granular pavements. Consequently, the HDM-4 structural deterioration model for
sealed granular pavements could not be re-calibrated. This outcome suggests that modifications to the
HDM-4 structural deterioration model are needed for sealed granular pavements.