Hawaii Highways Climate Adaptation Action Plan

In May 2021, the Hawaii Department of Transportation (HDOT) Highways Division released the Hawaii Highways Climate Adaptation Action Plan. The Action Plan will serve as a roadmap to make Hawaii’s highways more resilient to climate change based on a forward-looking analysis that recognizes the impacts of climate change-related hazards on transportation assets. This is a noteworthy step for Hawaii, which is updating its traditional highway design and planning processes. The Action Plan is a useful example for state departments of transportation, local metropolitan planning organizations, and other planners and policymakers looking to incorporate climate change impacts and considerations into transportation exposure assessments, plans, and designs.

The state’s highways administered by HDOT consist of beltways on low-lying coastal areas encircling islands and roadways on mountainous terrain. They were built and prepared using traditional transportation planning methodologies based on anticipated recurring natural hazards established through historical data. However, Hawaii’s highway assets are suffering from unanticipated extreme weather and climate change-related hazards threatening its system. This is posing ongoing safety risks and costing the state financially.

To address this issue, HDOT developed the Action Plan primarily to identify hazards including those linked to climate change affecting Hawaii’s highway assets through an exposure assessment and to formulate a comprehensive plan incorporating resiliency in the state's highway planning and design. 

The Action Plan is divided into four sections. Section 1 is an Introduction that gives an overview of the plan. Section 2 discusses the rationale for the Action Plan explaining the state's urgency to address the impacts of climate change on its highway assets, as articulated in an Exposure Assessment report, and the need to shift HDOT’s current practices to a forward-looking model incorporating climate change-related hazards in highway planning and design. Section 3 lays out an Implementation Plan that focuses on capacity building and improving institutional mechanisms and coordination within HDOT to execute the Action Plan. Section 4 shows the next steps HDOT anticipates taking to operationalize and build on the Action Plan in future investments and programs.

In addition to the Action Plan, the state also released an online All Hazard Map tool to decision-support tool to inform planning and adaptation actions. 

The Action Plan is a first step for HDOT in recognizing the impact of climate change-related hazards on Hawaii’s highway assets, such as roads, bridges, culverts and tunnels. The Action Plan is grounded in the findings of the Exposure Assessment report, as mentioned in Section 2. Through the Exposure Assessment, HDOT conducted an asset inventory of Hawaii’s highway system, describing the location of each asset, identifying the natural hazards that may impact each asset’s structural or functional performance, and the level of the asset’s exposure to these hazards. The Exposure Assessment will also help HDOT conduct more detailed vulnerability, risk, and resilience studies to better understand the potential socioeconomic consequences of different hazards and develop climate adaptation decisions.

The Action Plan discusses some of the past types of events HDOT considered in its traditional highway planning processes, which are also identified in the Exposure Assessment, such as coastal erosion and shoreline change; storm surge and high winds; intensive precipitation, landslides, rock falls, debris flows, and inland flooding; groundwater inundation; tsunamis; wildfires; lava flow; and past repair sites. In the Action Plan, HDOT emphasizes the need to consider the impacts of climate change-related hazards to highway assets, in addition to these historic events. Collectively, this list of events includes: rockfalls and landslides; sea-level rise (flooding and groundwater inundation); annual high tide flooding; coastal erosion; storm surges; tsunamis; wildfires; and lava flows  (which are not classified as a climate hazard but as an “other hazard”).

Building on the Exposure Assessment, HDOT developed an Implementation Plan in Section 3 that identifies actions the department can take to increase the resiliency of the state's highway system. The specific actions are categorized according to the different functional parts of HDOT and also the level of effort that will be necessary to implement them. This will help HDOT assign responsibility for different tasks and prioritize more immediate or low effort actions. 

 Response and Recovery

  • Assess emergency response capabilities considering changing institutional relationships. (Low)
  • Update policies and procedure for HDOT staff during emergency situations. (Low)
  • Enhance emergency response and recovery decision-support structures. (Medium)
  • Provide technical capability to consider betterment requests as part of Federal Highway Administration (FHWA) Emergency Relief Grants. (Low)

 Maintenance Programs

  • Ensure that maintenance and inspection databases are structured consistently to feed into future decision-making. (Low)

 Data-Driven Decisions

  • Invest in user-friendly, modern technologies for data collection and analysis. (Medium) 
  • Provide a data and evidence-driven foundation for HDOT’s decision-making processes. (Medium)   


  • Follow an adaptive design process for projects exposed to climate-related hazards. (Medium)
  • Consider climate change in technical and process guidance. (Medium)
  • Amend Internal Manuals to streamline procedures related to developing adaptive project designs and operational strategies. (Medium)
  • Conduct a pilot study on the use of an adaptative design process. (Medium)


  • Develop or amend programmatic agreements, particularly those that improve efficiency in environmental review processes as they reflect changing future environmental conditions. (Medium)
  • Explicitly recognize in policies and plans that climate-related effects are a significant challenge. (Medium)

 HDOT Lead/Resources

  • Establish clear authority and responsibility for climate adaptation and system resilience within HDOT. (Medium)
  • Create an environmental office, at the branch level or higher, that has a broad responsibility for HDOT’s environmental, climate adaptation, and system resilience efforts. (High)
  • Hire staff to lead the agency’s system resilience effort. (Medium)
  • Create a highway system resilience funding program. (High)


  • Provide a comprehensive and cross-agency staff training of the different components of HDOT’s climate adaptation and system resilience efforts. (Low)


  • Collaboratively develop implementation plans for statewide adaptation strategies. (Medium)
  • Reinforce current relationships with key agencies and other partners that are critical in implementing the action plan. (Low)
  • Acknowledge HDOT’s critical role in climate adaptation. (Low)

For next steps identified in Section 4 of the Action Plan, HDOT anticipates that it will continue pursuing a forward-looking approach by considering climate change impacts on future projects and developing a data-driven resilience program that will identify the extent and timing of hazards, the damage those hazards may cause, and the impact of those hazards to highway asset users.  

Publication Date: May 2021

Related Organizations:

  • Hawaii Department of Transportation


Resource Category:

Resource Types:

  • Agency guidance/policy
  • Assessment
  • Plans (other)

States Affected:


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