HDOT Climate Resilience Action Plan | May 2021

Executive

Summary

BACKGROUND Changing climatic conditions are creating challenges for Federal, State, and local government agencies throughout the United States. Hawai‘i is experiencing such challenges, which are in many cases unique to the Hawaiian Islands. The Highways Division of the Hawai‘i Department of Transportation (HDOT) recognizes its responsibility to better understand how changing climate conditions could impact the State’s portion of the National Highway System (NHS). The Hawai‘i Highways Climate Adaptation Action Plan (Action Plan) helps HDOT better define the extent and timing of these changing conditions on NHS facilities. Specific actions are identified on how climate change concerns can be considered and acted upon throughout HDOT’s programs, ensuring the viability of the highway system for Hawai‘is residents, visitors, communities, and businesses. HDOT is responsible for the condition and performance of approximately 971 (linear) miles of highways on 6 islands within the State. The effective management of these NHS highways is a top priority for HDOT because of their vital contribution toward community access, economic prosperity, national security, and overall mobility. The Action Plan provides a roadmap for HDOT’s Highways Division to make the highway system more resilient to climate-related effects. It presents an exposure assessment of climate hazards to the State’s highways based on both historical and future climate condition research and data. The Action Plan prioritizes recommendations in a multi-year Implementation Plan that encompasses all aspects of HDOT’s core functions and programs—funding, planning, designing, constructing, operating, maintaining, and protecting highway assets. It is considered a living document and will be revised as needed to reflect changes in conditions and implementation status. The intended audience is primarily HDOT management and staff but also includes Federal, State, and local agencies and government leaders; other county, city, and local governmental

agencies; utilities; communities, and businesses. HDOT is committed to working with all stakeholders in addressing the shared climate change challenges. EXPOSURE ASSESSMENT FINDINGS The hazards examined in this study are summarized in Table ES-1, Figure ES-2, and fully described in the Exposure Assessment document that was prepared as a companion document to this plan. A map identifying specific areas of concern is presented over the following pages. The State Highway Network was the focus of this study. Of the total mileage, 564 miles (58% of the network) are exposed to potential climate change stresses and lava flows (16% is attributable to lava flows) including 303 bridges (76% of the assessed bridges), 48 culverts (66% of the assessed culverts), and 6 tunnels (100% of the assessed tunnels). Note that lava flows are not climate-related hazards but were considered in a broad approach to increase highway network resilience. The mileage and assets exposed to each stressor, in some cases overlapping with other hazards, are presented below. Each of these conditions, except for lava flows as noted, is anticipated to be affected by climate change in Hawai‘i. It is important to think not only about past experience with such hazards, but also the anticipated changes that could alter the This document is one of two resources that outlines the potential threats from climate change to Hawai‘i Highways. This Plan is a companion to the online mapping platform maintained on HDOT’s website to enable the review of climate threats at a level of detail not possible in printed form. That site is located at: https://hidot.hawaii.gov/

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