Daniel K. Inouye Highway Extension

Project Overview

The Hawai‘i Department of Transportation (HDOT) and the Federal Highway Administration (FHWA) are proposing to construct the final arterial connection to complete the Daniel K. Inouye Highway (State Route [SR] 200, formerly known as Saddle Road) from Māmalahoa Highway (SR 190) to the Queen Ka‘ahumanu Highway (SR 19) in the South Kohala District, Hawai‘i Island. This project, known as the Daniel K. Inouye Highway Extension, will be an integral element of the road network for cross-island traffic, connecting transportation users to airports (Kona International Airport and Hilo International Airport), state harbors (Kawaihae and Hilo), beaches and resorts (South Kohala and Kona), and population centers (Hilo, Waimea, Waikoloa Village, and Kailua).

The Daniel K. Inouye Highway Extension Project aims to improve the general efficiency and operational traffic movement between East Hawai‘i and West Hawai‘i; support special traffic needs, including commercial truck traffic and military traffic between Kawaihae and the Pōhakuloa Training Area; and improve safety for all users.

The Daniel K. Inouye Highway Extension Project aims to improve the general safety, efficiency and operational traffic movement between East Hawai‘i and West Hawai‘i

Project History

1999: Saddle Road Extension EIS Preparation Notice published and public meeting held
2003-2010: Saddle Road Extension EIS put on hold while the U.S. Army prepared an EIS for expanded military training activities at the Pōhakuloa Training Area
2010: Saddle Road Final EIS and ROD published (with revised terminus, shifted southward)

2012: Revised State of Hawai‘i EISPN published and public meeting held
2014: Revised NEPA NOI published and public meeting held
2017: Draft EIS published, public hearing held, and comments received and complied. Final EIS was not completed
2018: Project put on hold prior to completion of Final EIS and ROD
due to lack of funding

Dry grass area adjacent to three-lane road with cloudy sky.

Group of trees adjacent to two-lane road.

Person sitting near large woody trees surrounded by boulders.

Grassy field with mountain and clouds in background.

Turning lanes onto road with grass in the foreground and background and cloudy sky.

Project timeline (subject to change). Previous Planning and Studies, including 2017 Draft EIS > Federal and State Environmental Impact Statement 2025 to 2028 > Design and Right-of-Way 2028 to 2035 > Construction 2031 to 2035 Environmental Impact Statement Phases Current Phase: Data Collection, Early Scoping; Informational Public Meeting Winter 2025 to Summer 2026 > Purpose and Need, Scoping; Scoping Meeting and Comment Period Summer to Fall 2026 > Evaluation > Draft EIS Development, Publication; Public Hearing and Comment Period Fall 2026 to Fall 2027> Evaluation > Final EIS, Record of Decision Public Updates Fall 2027 to Summer 2028

Current Phase

HDOT is currently reinitiating the project, including preparation of updated Environmental Impact Statements (EISs) compliant with the National Environmental Policy Act (NEPA) and Hawai‘i Environmental Policy Act (HEPA). The NEPA and HEPA EISs will reflect alternative refinements and updated environmental analyses that build upon and update the information published in the 2017 Draft EIS.

The Daniel K. Inouye Highway Extension Project study area is a corridor extending in an east-west direction for approximately 10.5 miles in the South Kohala District, from Māmalahoa Highway to Queen Ka‘ahumanu Highway. The 2017 Draft EIS included detailed analysis of three proposed alternative routes (see map), which will serve as the starting point for alternative refinements and additional analysis for this project phase. Updates regarding the alternative refinement process and/or specific alternative details will be available as the project progresses.

Project map showing Alternatives (2017)* Alternative 4, 5, 6, and major and minor roads The three alternatives extend from Māmalahoa Highway to Queen Ka‘ahumanu Highway.