The importance of research into the impacts of climate change on transport networks

Extreme climatic and weather events pose significant threats to road infrastructure, leading to profound social, environmental and economic repercussions. The 2021 Intergovernmental Panel on Climate Change (IPCC) report underscores a notable temperature rise over land (1.59°C from 2011–2020) attributed to human activities. This has resulted in more frequent and intense hot extremes, including heatwaves, as well as heavy precipitation events and other severe weather phenomena, with human-induced climate change being the primary catalyst. Additionally, the mean sea level has risen more rapidly since 1900 than in any preceding century over the last 3,000 years.

The unprecedented extreme weather events and climate change impacts across Australia and New Zealand highlight the essential role of roads and associated infrastructure in prevention, preparation, response and recovery activities. However, these events also expose the vulnerability of road infrastructure and the traveling public during and after climatic events. Severe natural disasters can lead to a wide range of economic, social and environmental impacts, from short-term inconveniences to long-term, life-altering effects.

The road networks in Australia and New Zealand encompass over 490,000 km of sealed roads and highways, 600,000 km of unsealed roads, as well as bridges, culverts, drainage systems and other related assets. Many of these assets and linkages are increasingly susceptible to future climate hazards.

State transport agencies in Australia and the New Zealand Transport Agency are tasked with ensuring that transport networks meet the needs of the community, industry and stakeholders by providing safe, reliable roads, bridges and paths that facilitate free movement and connectivity. Therefore, considering the impacts of extreme weather events and future climate change is crucial to maintaining safe and accessible road networks for the community.

Under normal operating conditions, government-controlled transport networks are expected to remain open to the public. However, road closures can occur due to unplanned events such as floods, cyclones, bushfires and major accidents, which can vary in duration and severity. To address this, the National Transport Research Organisation (NTRO) has been conducting research to develop solutions that transport agencies can implement to keep transport networks open and connected.

This article presents two case studies of recent NTRO research:

1. Understanding Infrastructure Vulnerability Due to Climate Change: Conducted under the Western Australian Road Research and Innovation Program (WARRIP), a collaboration between the NTRO and Main Roads Western Australia (Main Roads), this study delivered a new, strategic decision-making framework to assess the vulnerability of road networks and assets to future climate conditions. ‍
2. A Framework to Incorporate Bushfire Resilience in Road Design: Part of a joint initiative by the National Assets Centre of Excellence (NACOE) through the Queensland Department of Transport and Main Roads (TMR) and WARRIP, this study developed a framework that integrates bushfire prevention, preparedness, response, and recovery into the planning, design, construction and maintenance of transport infrastructure.

Case Study 1: Understanding infrastructure vulnerability due to climate change

This research developed a framework for assessing network vulnerability that provides a methodology for identifying weaknesses in the transportation network that make it susceptible to failure or degradation. The concept of vulnerability can be applied to individual assets or entire networks.

Vulnerability assessments or analyses are conducted to:

• Identify the functional level of service of a road or transportation network.
• Determine susceptibility to extreme weather incidents and the impacts of climate change.
• Assess the effects of these events on the network’s ability to maintain an acceptable level of service.

When designing the vulnerability assessment framework for Main Roads, the following suggestions were integrated:

• Utilise existing risk management processes for a more comprehensive evaluation of vulnerability.
• Ensure the methodology is applicable for both project-specific and general network-wide assessments, with findings from both types considered mutually. Findings should be presented in a shared location for future review.
• Use quantitative conclusions to facilitate easy comparison with other assessments, where possible.
• Set guidelines for datasets to assess climate change parameters and projections.
• Consider the biophysical and socioeconomic drivers of vulnerability and how these will evolve over the asset’s lifespan.
• Determine key indicators of risk and vulnerability applicable to most assets within the network. This allows for easy comparison of analyses and may simplify the vulnerability assessment model. However, this should not limit the use of other uncommon indicators, as they too impact vulnerability.
• Link an adaptation strategy to the vulnerability assessment. This proactive approach is key to building resilience throughout the network.
• Assess the consequential effects of impacts and vulnerabilities on one asset and their subsequent impacts on other assets in the network.

When identifying data requirements and sourcing data, the following recommendations were implemented:

• Establish a clear definition and robust method for assessing asset criticality as a priority for developing an assessment framework for managing future climate threats.
• Consider a methodology for identifying climate threats that accounts for new risks posed by future climate change.
• Define the scope of the assessment in terms of asset types and climate threats to determine the required data.
• Use data suitable for the assessment methodology and purpose, balancing accuracy, simplicity and costs. Stakeholders should be consulted on the pros and cons of applicable methods and the data needed to support them.
• Engage asset and network operations managers early in the network vulnerability assessment process. These managers likely have the best access to most, if not all, of the asset and network data required to implement the framework.
• Plan for climate change as a necessary step to help road agencies mitigate the risk of extreme climate and natural hazard events. A vulnerability assessment of the entire state road network provides strategic planners, asset and network managers, as well as investment decision-makers, with an evidence base to prioritise resilience-building investments.

Drawing on research findings, this project developed a bespoke climate change vulnerability assessment model for Western Australia. To refine the model, a pilot assessment was conducted using real-world asset data, climate change projections and stakeholder input. The pilot generated vulnerability ratings and visualisations for Main Roads WA assets facing future climate and natural hazards. This pilot demonstrated the feasibility of statewide network vulnerability assessments, informing future refinements and capacity building.

The data-driven approach enabled efficient, repeatable and robust assessments on a large scale with minimal resources. The methodology was adaptable to various asset types, infrastructure purposes and locations (urban, rural). It provided clear, understandable visualisations and consistent vulnerability scores.

While additional data, including local knowledge, is needed for comprehensive assessments, the pilot proved the viability of a network-wide approach. This project underscores the critical importance of understanding asset vulnerability to climate change to mitigate environmental, social and economic risks.

Case Study 2: A framework to incorporate bushfire resilience in road design

Roads play a crucial role during bushfire events in several ways. They provide essential access for emergency vehicles, aid and supplies, ensuring that help can reach affected areas promptly. Additionally, roads serve as evacuation routes, allowing the community to leave or reach evacuation centers safely. Furthermore, roads can act as fire breaks, helping to slow the progression of fires.

However, the functionality of roads can be compromised during bushfires due to several factors. Direct damage from falling trees, power lines and damage to structures and terrain can obstruct roads. Radiant heat can potentially melt soft materials such as bitumen, signage and line markings, further hindering road usability. Reduced visibility caused by smoke and changes in driver behavior due to fear can also lead to decreased road safety.

To address these challenges, it is essential to focus on prevention, preparedness, response and recovery. Prevention involves implementing roadside clearing and vegetation management to control fuel loads. Preparedness includes planning for the use of roads for emergency access. During bushfire events, organising evacuations and managing traffic are crucial response measures. Finally, recovery involves rebuilding and upgrading road infrastructure post-bushfire to ensure future resilience. The framework developed by NTRO assists road agencies in managing the risks to road infrastructure posed by bushfires. While there is extensive guidance available for bushfire management, applying it specifically to road corridors was identified as a gap by road agencies.

This framework includes strategies for:

• Designing and maintaining roadside vegetation to prevent bushfire ignition.
• Reducing the impact on infrastructure within road corridors to minimise damage.
• Ensuring safe evacuation routes and protecting road users by collaborating with emergency services.
• Restoring road operations swiftly after a bushfire to enable quick recovery.

The framework also emphasises the need for:

• Ensuring all actions comply with legal and regulatory frameworks, as it is crucial for alignment with legislation.
• Comprehensive planning that considers design, construction, maintenance and operational procedures in context.
• Stakeholder engagement involving all relevant parties in decision-making and implementation.
• Balancing prevention activities with environmental laws and regulations, as it is essential for environmental considerations.
• Coordination with other agencies to integrate strategies with those of utility providers and other stakeholders.
• Engaging relevant parties to manage and protect cultural heritage areas, which is is vital for cultural heritage protection.

By incorporating bushfire resilience into road infrastructure, agencies such as TMR and Main Roads can better plan and prepare for bushfire events. The framework provides a pathway for gap analysis in current bushfire management practices, improving internal resourcing and delegation of authority. It also lays the foundation for an agency-wide bushfire risk management program, covering all aspects of road infrastructure projects and general road network maintenance.

Furthermore, the framework serves as a single resource that can be shared with other agencies and governments, such as utility management teams, traffic control and disaster management departments. This allows for coordinated efforts and the integration of bushfire management practices across various sectors.

Summary

Transport networks are vital lifelines that must remain operational under most conditions. However, extreme weather events and unforeseen incidents can disrupt these networks, causing significant economic and social impacts. The initiatives presented in this article aim to equip transport agencies with the tools and knowledge to build more resilient and sustainable transport systems. Both projects address critical aspects of infrastructure resilience, particularly in the context of climate change. By investing in research and development, we can significantly improve the ability of our transport networks to withstand future challenges.

By combining their findings, we can develop a more comprehensive approach to safeguarding road networks and assets. The network vulnerability assessment methodology can be used to identify specific road segments or assets most vulnerable to future climate impacts, including extreme heat, heavy rainfall and sea-level rise. Then, the bushfire framework can be used to assess the potential for prevention, preparedness, repsonse and recovery strategies for bushfires to be implemented for these vulnerable segments. By combining these assessments, we can prioritise interventions based on the level of risk posed by both climate change and bushfires. This could involve:

• Implementing measures to reduce vulnerability to climate change, such as improved drainage systems or heat-resistant materials.
• Implementing measures to reduce the risk of bushfires, such as creating firebreaks or clearing flammable vegetation.
• Developing emergency response plans and ensuring that infrastructure is designed to withstand the impacts of bushfires.

Use cases for this research may be, but are not limited to:  

• The combined frameworks informing decisions about new road construction, including route selection, design standards and materials.
• Existing roads being assessed for vulnerabilities and upgraded to enhance resilience to both climate change and bushfires.
• The frameworks helping to identify critical infrastructure that may be at risk during extreme weather events or bushfires, allowing for targeted emergency response and recovery efforts.
• The combined findings informing the development of policies and guidelines for infrastructure resilience in regions prone to both climate change and bushfires.