Manukau Harbour Crossing, Auckland, New Zealand

Manukau Harbour Crossing, Auckland, New Zealand


Transit New Zealand



The scheme provided for the widening of the existing State Highway 20 between Walmsley Road and Queenstown Road. It also involved modification and rebuilding of several existing motorway bridges, foot bridges and the construction of a duplicate bridge over the Manukau Harbour. A new interchange was also planned at Gloucester Park, a relic explosion crater.

Significant environmental design and construction constraints dictated the consideration of a low level embankment, constructed with ultra-light weight polystyrene fill for the new carriageways crossing the infilled crater within the Hōpua tuff ring.

This project was completed in 2015.

Services provided:

  • Geotechnical investigations
  • Interpretive reporting
  • Development of specimen design, including: 
  • Bridge foundations
  • Retaining structure
  • Lightweight polystyrene embankments
  • Hydrology and drainage design
  • Environmental planning and resource consents
  • Pavement design
  • Presentation of evidence in support of the works to the public hearing
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