A major infrastructure project that became an IPENZ Award winning engineering achievement.
Land instability and erosion resulted in Pier 7 of the Makatote Viaduct being vulnerable to foundation failure. The foundation problem was identified as the highest structural risk on the NZ Railway Network. Located between Ohakune and National Park, the Makatote Viaduct is the third highest railway viaduct in NZ. ONTRACK (now KiwiRail) undertook a project to underpin the vulnerable foundations.
The engineering team faced demanding constraints and difficulties. The project was effectively undertaken inside a National Park with numerous environmental challenges including undertaking construction in rare blue duck habitat and in a pristine trout spawning stream. Most critically, there was a possibility that the construction activities may in themselves destabilise the viaduct. Led by ONTRACK (now KiwiRail), Fulton Hogan and specialist engineering consultants worked collaboratively to successfully complete the $4.2M project. Due to the vulnerability of the pier and the difficult volcanic boulder and ash geology, vibrations were minimised through an innovative technique where the piles were delicately oscillated into the ground. High pressure artesian water was encountered on one pile which necessitated a creative redesign involving a telescopic pile to prevent the pressurised ground water undermining the viaduct.
The project team achieved exceptional environmental compliance in a highly sensitive setting.