Kamehameha Highway is the only route between Kahaluu and Haleiwa, so when any portion of the road is damaged or blocked, it’s a major problem. But the road is in trouble, particularly on the Windward side: threatened by deteriorating infrastructure on land, and rising sea levels and eroding beaches oceanside.
When news about both dilemmas crops up over a few days, with a major water main break in Punaluu and a plan to shore up crumbling shoreline in Kaaawa, it’s a serious heads-up to prepare for some needed fixes — and driving delays — now and in the long run.
Repairs to keep the road open are an immediate need, but long-term plans to ensure that a roadway remains viable in the future also are necessary. Planners will need to make complex calculations that take the Windward infrastructure, the state of its coastline and threats caused by sea level rise into account.
On Friday, the break involving a 30-inch pipeline near Punaluu Beach Park flooded the road with gushing water, creating a sinkhole large enough to drive a car into. And that’s what happened, accidentally.
Thankfully, no one was seriously injured. The pipeline has now been repaired, and crews continue to work on the roadway.
The damage caused by the broken main is alarming. More alarming yet is the prospect that mains could continue to fail. A 30-year master plan prepared by Honolulu’s Board of Water Supply (BWS) in 2016 concluded that this part of Oahu is vulnerable to repeated main breaks as the system continues to age. However, fixes are expensive, costing twice as much as comparable work on the West Coast, and BWS funding comes solely from water-use fees.
Further, sea level rise poses a growing threat. A 2019 BWS report on impacts of climate change projects that Kamehameha Highway could be vulnerable as soon as 2030.
A 2017 state Department of Land and Natural Resources (DLNR) report on climate change and its effects on Hawaii’s infrastructure, including water delivery and roadways, calls this part of Kamehameha Highway “one of the most vulnerable coastal highways in Hawaii.”
On Thursday, Hawaii’s Department of Transportation released its final environmental assessment for a plan to build a $2 million, 450-foot-long rock fortification along the Kaaawa shoreline, forestalling Kamehameha Highway’s potential collapse.
The assessment notes that the two-lane highway, which carries an average of 13,000 vehicles per day, comes very close to the coastline in many places — within a few feet. When high tides and surf combine, the ocean washes over the highway, leaving the road’s shoulder “dangerously undermined.”
Construction could begin in the fall, with daytime work going on for about four months.
The catch: This revetment is projected to have a lifespan of just 25 years, because sea level rise is likely to inundate the road area. That’s going to require a much bigger fix.
“Global climate change and sea level rise are affecting Hawaii’s coastlines — from now into the future — and will necessitate long-term planning,” the DLNR report states.
Hawaii should be accelerating work on infrastructure strengthening projects that protect against the effects of global warming, including sea level rise. Part of this planning should include an aggressive hunt for federal assistance.
The $1 trillion federal infrastructure bill enacted in 2021 includes at least $1.2 billion earmarked to repair Hawaii’s roads and make them more resilient to climate change. Additionally, the infrastructure funding includes $7.5 billion in competitive grants to support road and transportation projects, and Hawaii surely qualifies for some portion of this.
Kamehameha Highway is essential, and it’s threatened. Problems will only multiply in the near future without careful risk assessment and concerted efforts — by the state and county to leverage expertise and funding, and to explore necessary federal assistance.
