Ngaruawahia Bypass
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Client: NZTA
Sector: Foundations
Location: Ngaruawahia
Contract Value: Approx $100M
Completed: Dec 2014
Main Contractor: Fletcher Construction Infrastructure

The Ngaruawahia Bypass runs from Taupiri to Horotiu. It will initially connect to SH1 at Taupiri in the north and to the beginning of the Te Rapa Bypass at Horotiu in the south. Future connections will also be provided to the Huntly Bypass and the Hamilton Bypass.

The contract is being led by Fletcher Construction Infrastructure with Brian Perry Civil resources joining the project team in a joint venture arrangement to carry out drainage, piling and ground improvement works (in joint venture with Keller Ground Engineering).

The Ngaruawahia Bypass is 12.5km long and has a total of 7 bridge structures, 6 of the bridge structures will be supported by 99, 710mm diameter bottom driven piles (average depth 30m). The remaining and largest bridge, spanning the Waikato River, will be supported by 26, 1600mm large diameter bored piles. All piles are drilled using a Polymer Fluid Support System and will also be base grouted.

The Bypass also hosts two major interchanges, Gordonton and Lake Road. For seismic mitigation the installation of approximately 1500 stone columns (average depth 11m) will be installed at these interchanges.  It is expected that once the bypass is complete in 2013-2014 it will reduce the travelling time from Auckland to Cambridge by 32 minutes.


  • 99No 710mm diameter bottom driven piles (average 30m deep)
  • 1500No stone columns (average 11m deep)
  • 26No 1600mm diameter bored piles. Drilled with polymer and base grouted
  • 60m of temporary sheet pile wall
  • Temporary works for large cranes at WRB (scope unknown)
  • 4No 1000mm diameter bored sign gantry piles

Work Update – September 2014

BPC and Fletcher are working collaborately to complete the earthworks, environmental, MSE and batter chute works.

Drainage works are complete with the exception of some tricky PVC pipework at Lake Road Bridge.

The project is 97% complete. We are currently working hard to stabilize the last of the embankments on Kainui and River road bridge embankments. Last stages include close out stockpiles for the job, delete environmental ponds, lay down Fortrac matting, tidy up the last of the topsoil around the headwalls and small drainage tie ins.