In 2011, the state Department of Transportation (HDOT) began a project to realign a stretch of Kamehameha Highway near Laniakea Beach, for good reason: Shoreline erosion and relentless sea level rise threaten to undermine the stability and reliability of the roadway. It needs to be moved inland.

This week, the DOT detailed its plan in a 600-page draft environmental assessment. But the priorities have changed. Sea level rise now is a secondary, although still critical, concern; pedestrian safety has become Job 1.

For years now, sightseers have clogged traffic and risked life and limb as they cross Kamehameha Highway to watch the green sea turtles feeding and resting at Laniakea Beach.

Numerous attempts to control the crowds have been tried, with little success. Concrete barriers were erected and then taken down by a judge’s order. But in 2019, a 10-year-old boy from California tried to cross the road and was struck by a car, leaving him badly injured.

Area residents rightly complained about the dangers and inconvenience caused by this uncontrolled activity.

“In response, HDOT elevated pedestrian safety at this location to become the primary project purpose,” the assessment said.

Given the unfortunate persistence of people who simply must look at turtles, that means expediency over longevity.

The DOT estimates it will cost $12 million to build 1,000 feet of realigned highway about 50 feet inland — not including the cost of obtaining rights-of-way. The mauka side of the current highway section would be converted into a pedestrian/bicycle pathway. The project would be finished in 2025 — if everything goes smoothly.

It’s also a temporary fix, assuming current forecasts of sea level rise hold.

“As sea level rise surpasses the 2.0-foot sea level rise benchmark … the realigned Highway would begin to experience inundation at the lower-lying areas near Lauhulu Stream Bridge,” the assessment said. “Based on this understanding, the proposed realignment would serve as a mid-term mitigation, providing an additional 45 years of reliable service.”

A more farsighted alternative, considered but rejected, would have moved the highway about 1,000 feet inland, a 6-year, $70 million project. But this alternative risked disturbing Native Hawaiian cultural and historical artifacts.

The Laniakea project will make that small stretch of coastline safer, with a more resilient highway — for now.

It’s also a preview of the daunting challenges ahead for Hawaii’s coastal roads.