The O’Sullivan’s Bluffs, Attenuator Fence project south of Murchison delivered a 180‑metre‑long, 30‑metre‑high rockfall protection system, making it one of the longest attenuator fences of its kind in New Zealand. Installed on a steep, weather‑exposed slope above State Highway 6, the works play a critical role in protecting road users from rockfall hazards in a high‑risk environment.
The project required extensive preparation and staged construction to safely stabilise the slope while maintaining traffic flow on one of the region’s key transport routes. Key works included scaling and controlled blasting of loose rock, installation of over 200+ rock anchors and investigation bolts, placement of approximately 6,300 m² of Tecco G65/3 high‑tensile mesh, construction and installation of 18 attenuator fence posts with foundations and installation of 1.6 km of wire rope for longitudinal cables, bracing and tie‑backs.
All works were completed while keeping one lane of live traffic open, with short, carefully managed closures required only during heli-lifts, blasting and scaling activities.
Due to challenging terrain and limited access, the project relied on a combination of rope access techniques and specialist plant, including two wagon drill rigs and a 30 m boom lift modified for drilling operations, a 60‑tonne crane for fence post and barrier installation and helicopter lifts to transport drill rigs, mesh rolls, anchor bars and grout equipment to the upper slope. These methods allowed the team to work efficiently and safely despite steep slopes, wind exposure and variable ground conditions.
The project was delivered over approximately 5 and a half months, from October 2025 to March 2026, with all systems installed, tested and accepted. The completed attenuator fence provides long‑term resilience for State Highway 6, significantly reducing rockfall risk and improving safety for road users.
