Oahu

Pali Highway Landslide Mitigation addresses chronic rockfall and debris risks along Oahu's Route 61 between the Nuuanu Pali Tunnels and Kailua, where heavy rains in 2019 triggered major slides from Old Pali Road above, dumping boulders and concrete onto the lanes and closing this vital Windward-to-Honolulu artery.​

The emergency response, completed by early 2020 as part of a broader resurfacing project, restored full access after weeks of contraflow and single-lane ops, protecting commuters, tourists, and emergency routes through the Koolau Mountains while blending fixes into the highway's historic landscape.​

From a technical standpoint, crews built an 80-foot precast concrete rock shed with aesthetic matching to the tunnel portals using colored concrete and textured slabs, plus slope mesh stabilization, attenuators to catch debris, guardrail upgrades, and 5 miles of asphalt resurfacing with stone matrix overlay for durability against Oahu's wet conditions. Phased night work and environmental compliance ensured minimal disruption on this narrow, high-traffic pass, with the $20 million effort (including federal relief) setting a model for Hawaii DOT's slope resilience in steep terrain.