Manawatu Gorge – Te Ahu a Turanga Project

State Highway 3 runs through the Manawatū Gorge providing a critical connection between Ashhurst and Woodville, carrying over 7,500 vehicles per day. In 2017, a series of severe weather events caused a major landslide blocking the road and forcing all traffic onto the steep, narrow Saddle Road creating significant inconvenience, cost, and delays for the many users.

To provide a long-term solution, an alliance of Waka Kotahi NZ Transport Agency, Fulton Hogan, HEB Construction, Aurecon, WSP, and local iwi partners, was formed called Te Ahu a Turanga. The responsibility of this alliance was to deliver a new 11.5km, four-lane route designed to restore a safe, efficient, and reliable access across the Ruahine Range.

The project brought together more than 5,000 people to make it a reality. Cirtex was involved from the outset, providing design support and advice in the early stages, followed by product supply, onsite training, and ongoing support throughout construction to help achieve the project’s complex engineering and environmental objectives.

DESIGN

The combination of steep terrain, complex ground conditions, and high rainfall the team with significant challenges, working closely with Cirtex the use of DuraForce separation geotextile and GridTex geogrid was incorporated in the design of the pavement layers removing the need for extensive undercutting of the poor subgrades while still providing the performance required. The DuraGreen and DuraMesh retaining wall systems along with StrataGrid High strength reinforcement geogrid was used extensively to provide retaining structures in the gully fills and bridge approaches throughout the project.

To ensure sediment run off was controlled more than 50 sediment retention ponds and extensive perimeter sediment control defenses were needed. Cirtex supported the project with a full range of erosion and sediment control solutions to meet these needed.

Throughout the project the need for extensive temporary access roads and crane platforms were required, Cirtex assisted with the design and supply using high strength StrataGrid reinforcement geogrid to provide crane platforms and DuraForce woven and non-woven geotextiles for the access tracks to ensure safe and cost-effective access was provided to allow the main construction works to proceed.

INSTALLATION

Cirtex worked closely with the contractor and site engineers to provide support and training in site to ensure that the products and systems that had been designed into the project were installed seamlessly and correctly to ensure that project was a success for all involved.

Te Ahu a Turanga is a transformative project providing a critical link to connect communities and add the further development in the areas,  Cirtex is proud to have partnered with the Alliance to deliver a long-term solution that support Waka Kotahi’s vision for resilience, safety, and sustainability.

The Cirtex products used provided the following benefits to the project: 

• Complete geosynthetic range.
• On-site technical support.
• Certified environmental solutions.
• Scalable supply capabilities.
• Durable, high-performance systems