Can Roads Designed Yesterday Survive Tomorrow? Adapting Asset Planning Tools for Climate Change

The road subsector is considered one of the key production sub-sectors that tends to be affected by climate and weather variability. Increased precipitation can lead to flooding that may cut-off the network, wash-away sections, and lead to landslides, while increased temperature speeds-up the ageing of materials reducing the overall life of the asset. The Highway Development and Management Model (HDM-4), one of the primary asset management tools used in developing economies was developed in the early 2000’s and used by over 1000 clients for asset investment planning. While valuable for traditional asset management, HDM-4 presents significant limitations when applied to climate resilience planning. Based on static climate assumptions, with inadequate damage assessment, and insufficient economic analysis for climate resilience planning, HDM-4 is unable to capture accelerated deterioration from extreme climates, catastrophic failures, and cascading impacts from climate change.

To tackle these challenges, this research proposes two complementary approaches that address two road failure modes: (1) direct failure and (2) delayed failure. The first approach, dubbed, “Resilience Module” applies a well-known system-of-systems approach to assess the vulnerability of the asset, economically quantify direct and indirect damages from hazard events, and propose adaptation interventions that provide the best returns. The second approach addresses the gradual “delayed failure” modes.  Unlike landslides or floods that typically cause sudden damage to assets, extreme heat and some flooding events affect roads through progressive deterioration of the road pavement. This approach addresses these failures through climate-shift factors that were statistically derived to modify the existing deterioration equations. By determining which climate variables are most influential to road pavement deterioration, the research developed a set of multiplier factors that adjust HDM-4’s existing deterioration equations to capture intensifying extreme-heat conditions, flooding, and compound climate stressors.

Together, these approaches build on HDM-4’s strength of prediction, based on historical conditions to create a model that can handle future climates. The framework allows for the quantification of direct and indirect costs from catastrophic events, and accelerated deterioration estimates from changing conditions. It provides a comprehensive risk assessment that integrates exposure analysis, vulnerability evaluation, economic impact estimation, and increased maintenance costs from accelerated degradation across road assets.

By working within existing institutional frameworks and tools, this methodology gives road agencies a practical pathway to integrate climate change into infrastructure planning. This is crucial in ensuring that the limited adaptation resources are invested purposefully where they can deliver the greatest resilience benefits against mounting climate pressures.