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AMETI Eastern Busway Retaining Walls

AMETI Eastern Busway Retaining Walls

The Auckland Manukau Eastern Transport Initiative (AMETI) Eastern Busway is a group of projects in Southeast Auckland which will significantly improve transport choices, reliability, and journey times in Auckland and other parts of the region. The busway is being built on the north side of Lagoon Drive by widening the roadway on the northern cliff side, avoiding impacts on the basin.

As part of this widening, two large cut slopes were created, up to 11m high in places, which required soil nailing and a slope stabilisation mesh facing. GeoStabilization New Zealand Ltd (GeoStabilization NZ) competitively tendered for this slope stabilisation package and during the preliminary stage, our engineering team identified areas where enhancements to the conforming design could be made including widening of the anchor spacing as well as shortening of the anchors. As the proposed changes were only minor ‘enhancements’ to the conforming solution, and the design intend and overall solution was not changing, no changes were needed on the building consent.

With the risk of collapsing ground and likely need for casing in the mixed, welded/unwelded volcanic Tuff material, GeoStabilizationNZ also proposed the use of a self-drilling, grout flush anchor system using our low carbon steel bar. This product, with it’s superior durability and lower ductility, was used extensively throughout the Kaikoura earthquake rebuild having been heavily scrutinised and reviewed by the wider NCTIR engineering team (BECA, WSP etc). The enhancements resulted in significant cost savings for the client, as well as a reduced product duration. With a robust quality assurance programme exceeding the requirements of the conforming specification, the client was provided with an high-quality, cost-effective and fit-for-purpose solution that aligned with the overall project requirements.

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