Environment
- Publication no: AP-R779-26
- ISBN: 978-1-923617-77-3
- Published: 29 October 2026
- PDF (free) Download
The purpose of this report is to guide the selection and design of pavements across varying climatic conditions. This report addresses the need for improved projections of Weighted Mean Annual Pavement Temperature (WMAPT) and Maximum Pavement Surface Temperature (Tmax), critical parameters for the design of asphalt and foamed-bitumen pavements, and the selection of sprayed seal surfacings.
The methodology involved examining the limitations of global climate models and recommends an ensemble approach that averages outputs from multiple downscaled climate models. These models have been used to evaluate potential future climate conditions and develop WMAPT and Tmax estimates for locations across Australia and New Zealand. The results indicate a general increase in both parameters under the emissions scenarios investigated, although regional variations are evident. The largest increases are projected for parts of northern and western Australia, while some locations in southern New Zealand may experience decreases.
If adopted, this research has the potential to influence the design of pavements incorporating asphalt and foamed-bitumen-stabilised materials that are currently designed in accordance with Austroads Guide to Pavement Technology Part 2 as well as the selection of sprayed seal binder and sprayed seal type in accordance with Austroads Guide to Pavement Technology Part 4K.
- Summary
- 1. Introduction
- 1.1 Purpose
- 1.2 Background
- 1.2.1 Climate modelling
- 1.3 Scope
- 1.4 Methodology
- 1.5 Structure
- 1.6 Key terms and acronyms
- 2. Background on Climate Model Projections
- 2.1 Scenario analysis
- 2.2 Limitations of Global Climate Models
- 2.3 Downscaled climate model projections
- 2.4 Managing uncertainty in climate model projections
- 2.5 Requirements for climate model projections of temperature for WMAPT, T90 and Tmax calculations
- 3. Literature Review
- 3.1 Overview of available data sources
- 3.1.1 CSIRO projections for Australia
- 3.1.2 NIWA projections for New Zealand
- 3.1.3 NASA NEX-GDDP global projections
- 3.2 Comparison of available data sources
- 3.3 Managing future climate uncertainty
- 3.4 Summary of key findings from literature review
- 3.1 Overview of available data sources
- 4. Climate Modelling
- 4.1 Climate modelling and projections
- 4.2 Climate scenarios
- 4.3 Downscaled projections
- 4.4 Historical climate comparisons
- 4.5 Calculation methodology
- 5. Results and Interpretations
- 5.1 Model variabilities trends
- 5.2 Model variabilities trends
- 5.2.1 WMAPT variabilities across model ensembles
- 5.2.2 Tmax variabilities across model ensembles
- 5.3 Averages of model ensembles based on future projected data
- 5.3.1 Changes in WMAPT averages
- 5.3.2 Changes in Tmax averages
- 5.4 Most impacted locations
- 5.5 Changes between current and projected WMAPT values
- 5.6 Changes between currently published and projected Tmax values
- 6. Summary of Findings
- 6.1 Future research opportunities
References
- 6.1 Future research opportunities
- Appendix A Detailed Methodology and Assumptions
- A.1 Weighted Mean Average Pavement Temperature
- A.2 Decile 9 maximum temperature and maximum pavement surface temperature
- A.3 Impact of Tmax on sprayed seal selection and design
- Appendix B WMAPT and Tmax forecasts for selected locations