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Cover of Austroads Road Deterioration Model Update: Deflection
Austroads Road Deterioration Model Update: Deflection
  • Publication no: AP-T367-23
  • ISBN: 978-1-922700-67-4
  • Published: 20 January 2023

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 was undertaken early in the project which determined that these datasets were not appropriate at this stage for developing a refined structural RD model.

Development of a structural RD model was therefore based on the extensive time series captured by the LTPP/LTPPM datasets to produce a single structural RD model for flexible sprayed sealed pavements. The structural RD model was based on a mechanistic‑empirical deterministic approach using a multi-variate non‑linear regression (MVNLR) analysis. Seasonal correction of the measured maximum deflection proved to be problematic using measures of the lower soil moisture content, so the corrections were made using the current Austroads approach to seasonal variation.

Watch a webinar with Dr Tim Martin, Ranita Sen and Tyrone Toole for an overview of the development of the four road deterioration models.

  • Summary
  • 1. Introduction
    • 1.1 Background
    • 1.2 Purpose
    • 1.3 Scope
    • 1.4 Methodology
  • 2. Literature Review
    • 2.1 Overview
    • 2.2 Pavement Performance
      • 2.2.1 Limit of Gradual Deterioration
    • 2.3 Assessment of Pavement Performance
    • 2.3.1 Functional Performance Measures
    • 2.3.2 Structural Indicators
    • 2.4 Review of Recent Modelling Practice
      • 2.4.1 Typical Modelling Approaches
      • 2.4.2 Machine Learning with Big Datasets
      • 2.4.3 Application of ML to Pavement Deterioration Modelling
    • 2.5 Selection of Appropriate Modelling Approaches
      • 2.5.1 Expected Modelling Approach
      • 2.5.2 Proof of Concept for TSD Datasets
  • 3. Data Review
    • 3.1 Data for Analysis
    • 3.2 Data Requested from Road Agencies
    • 3.3 Review of the Data from Australian Road Agencies
      • 3.3.1 Transport for New South Wales (TfNSW) Data
      • 3.3.2 Queensland Department of Transport and Main Roads (TMR) Data
      • 3.3.3 Main Roads Western Australia (MRWA) Data
      • 3.3.4 Department of Planning, Transport and Infrastructure (DPTI) South Australia Data
      • 3.3.5 Department of Infrastructure, Planning and Logistics (DIPL) Northern Territory Data
      • 3.3.6 Department of State Growth (DSG) Tasmania Data
      • 3.3.7 Summary of Road Agency Data Supplied
    • 3.4 Missing Data for Proof-of-concept TSD Dataset
      • 3.4.1 Climate Information
      • 3.4.2 Soil Reactivity
      • 3.4.3 Sub-soil Drainage Information
      • 3.4.4 Additional Information Supplied by TfNSW
    • 3.5 Review of the LTPP/LTPPM Data
      • 3.5.1 Overview of Austroads LTPP/LTPPM Data
      • 3.5.2 Usability of Austroads LTPP/LTPPM Data
      • 3.5.3 Usability of New Zealand LTPP Data
  • 4. Proof-of-Concept Modelling Approach Using the TfNSW TSD Dataset
    • 4.1 General
    • 4.2 Methodology and Analysis
      • 4.2.1 Rate of Change of Deflection
      • 4.2.2 Cluster Analysis
      • 4.2.3 Presence of Maintenance in the TSD Dataset
      • 4.2.4 Variables Influencing Structural Deterioration
    • 4.3 Proof-of-Concept Structural Deterioration Model
    • 4.4 Conclusions
  • 5. Development of the Structural RD Model
    • 5.1 General Approach and Limitations
      • 5.1.1 Data Summary
    • 5.2 Treatment of Independent Variables
      • 5.2.1 Seasonal Correction of Measured Deflection
      • 5.2.2 Estimation of the Design D0 Deflection for the D0/D0i Structural RD Model
    • 5.3 Development of the D0/D0i Structural RD Model
      • 5.3.1 Initial D0/D0i Structural RD Model based on Design D0 Deflection
      • 5.3.2 D0/D0i Structural RD Model based on a Recursive Approach to Estimate Design D0 Deflection
    • 5.4 Review of the D0/D0i Structural Model Performance
      • 5.4.1 Parametric Study
      • 5.4.2 Comparison with Austroads 2010 RD Structural Model
  • 6. Conclusions
  • References
  • Appendix A Multivariate Non-Linear Regression Analysis Outputs
    • A.1 Deflection Ratio, D0/D0i, Structural Deterioration Model
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