Rockfall on key North Shore highway highlight growing concern for high-risk roads

Kamehameha Highway near Waimea Bay is now considered an emergency traffic zone.
Published: Feb. 9, 2023 at 8:44 AM HST|Updated: Feb. 9, 2023 at 9:20 AM HST
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HONOLULU (HawaiiNewsNow) - Four days after massive boulders fell from the hill above Kamehameha Highway, the state Department of Transportation is still working to shore up the key roadway at Waimea Bay.

It is now considered an emergency traffic zone. That will allow the state to get funding and perms sooner and expedite the construction process.

On Tuesday, DOT completed work to reset the barrier on Kamehameha Highway meant to slow down and deflect falling rocks from making it to the roadway. It cost about $130,000.

[RELATED: Crews dislodge huge boulders above North Shore highway as part of slope stabilization efforts]

As next steps, DOT’s highway division wants to construct a 15-foot high fence that will stretch down a 190-foot portion of Kamehameha Highway.

Workers estimate that the project would cost approximately $1.2 million and be completed by March of this year.

Meanwhile, there are other roadways in Hawaii considered high-risk for rockfalls.

According to the transportation department, the current top 10 sites on the state highway system are:

Statewide RankingHighway #DistrictHighway NameBegin MPEnd MPEnd MP
183OahuKamehameha Highway5.45.52R
219HawaiiHawaii Belt Road21.0421.49L
319HawaiiHawaii Belt Road25.7726.06L
456KauaiKuhio Highway24.7925.01L
519HawaiiHawaii Belt Road21.621.85L
6560KauaiKuhio Highway0.661.17L
730MauiHonoapiilani Highway10.3310.44TOP
861OahuPali Highway5.956.04TOP
919HawaiiHawaii Belt Road26.2726.72L
1061OahuPali Highway6.126.55R

DOT officials said the hazardous areas are ranked based on factors including:

  • Slope height
  • Presence of catchment (e.g., a ditch or flat area between the slope and the road)
  • Average vehicle risk (e.g., how many vehicles drive through this section on average)
  • Sight distance
  • Roadway width
  • Geological character of the slope
  • Volume per rockfall event, climate and/or presence of water on slope
  • Rockfall history and presence of protective systems

#1 on the statewide list is an area of Kamehameha Highway but officials said the Feb. 5 rockfall that occurred on Kamehameha Highway near Waimea Bay ranked 13 for rockfall risk.

Also on Oahu, two sections on Pali Highway ranked #8 and #10. Both of those areas on the windward side of the tunnel experienced a massive rockslide which closed the Pali in 2019 and forced an extension of the tunnel.

With the emergency zone designation, the transportation department is required to have a public meeting to discuss those plans.

A virtual meeting will be held on Thursday at 12:30 p.m. for anyone wishing to comment on the designation. To join the virtual meeting, click here.

For more information on DOT’s next steps for Kamehameha Highway near Waimea Bay, click here.