WAILUKU, Maui >> The state Department of Transportation is awaiting word on its application for a $25 million federal grant to help offset the estimated $90 million in design and construction costs to realign 4.5 miles of Honoa­piilani Highway that are vulnerable to sea-level rise and coastal erosion.

The highway is the primary link between West Maui and the rest of the island, handling an average of 17,200 vehicles daily, according to DOT, including commuters and tourists coming and going from the region’s resorts. The stretch of roadway from Ukumehame to Launiupoko proposed for realignment is mere steps from the shoreline in some spots, and it’s not unusual for waves to wash over the two-lane highway during periods of high surf.

Olowalu, at roughly midpoint, is ranked as the No. 2 priority site in DOT’s 2019 Statewide Coastal Highway Program Report, and Ukumehame is 12th.

In July DOT submitted a grant proposal under the U.S. Department of Transportation’s Rebuilding American Infrastructure with Sustainability and Equity, or RAISE, program, seeking the maximum grant award of $25 million for the realignment.

The program is highly competitive, according to the federal agency, with 680 projects funded out of over 9,700 applications so far. It is one of its few discretionary programs in which regional and local governments directly compete for transportation funding.

Hawaii last received a RAISE grant in 2019 of $20 million for an elevated walkway over Ala Moana Boulevard.

The proposed Ukumehame-to-Launiupoko alignment would connect to the 2.7-mile Lahaina Bypass Phase 1B-2, which opened in April 2018 and runs mauka of Lahaina town. That segment cost $38.6 million.

The state DOT said it won’t learn until later in the year whether its RAISE proposal is approved. If the grant comes through, the remaining costs would be covered by 80% federal highways funding and 20% from the state, according to DOT spokeswoman Shelly Kunishige.

Should the project be fully funded, construction is anticipated to begin in late 2024. DOT said it will work closely with Maui County and the state Department of Land and Natural Resources, which own most of the land needed for the proposed realignment.

“Honoapiilani Highway is a critical route and we are taking the steps necessary to ensure it is protected from sea-level rise and coastal erosion,” said DOT Deputy Director for Highways Ed Sniffen in a statement. “As the planning, environment and design process continues we’ll be asking for public input and support for the realignment.”

In the meantime, temporary mitigation action to protect the highway includes shifting the existing alignment approximately 12 feet mauka between mile markers 12.97 and 14.49. Preliminary engineering for the work is underway, with the total cost estimated at $4 million, DOT said.

The Lahaina Bypass Phase 1C, which would continue the bypass road north to Kaanapali at an estimated cost of $40 million, remains on DOT’s list of long-range Maui projects, Kunishige said. The Phase 1C time frame “will be based on funding availability and system prioritization,” she said.