Pukeahu National War Memorial Park and Underpass (Arras Tunnel)

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INFRASTRUCTURE AWARD

Pukeahu National War Memorial Park and Underpass (Arras Tunnel), Wellington

 

Submitted by:  Memorial Park Alliance

Owners:  NZ Transport Agency  /  Ministry for Culture and Heritage

Architect:  Wraight Athfield Landscape and Architecture

Consulting Engineers:  Tonkin & Taylor  /  AECOM

Contractors:  HEB Construction  /  Downer NZ

 

Summary:

Unique engineering solutions were required to construct Arras Tunnel, which takes state highway traffic beneath Pukeahu National War Memorial Park, so it can withstand a potential 1-in-2500 year earthquake in a central Wellington area of high seismicity.

The park and tunnel comprise the Government’s centerpiece WWI centenary project, designed and constructed by the Memorial Park Alliance of NZTA, Downer NZ, HEB Construction, Tonkin & Taylor and Aecom (formerly URS).

Collaborative alliance teamwork with involvement from Wraight Athfield Landscape and Architecture enabled the original competition-winning park concept to be developed to integrate tunnel and park.

Concrete was used structurally and symbolically as a key element to ensure the longevity of the 21,000m2 park and 130m-long tunnel as a national commemorative site.

Land formation, high water table, huge seismic-induced soil pressures and a historic sewer prompted engineering solutions that achieved structural stability for the tunnel as well as time savings.  Innovations included custom-belled tension piles, a poured concrete structure and a fit-for-purpose concrete mix.

Both tunnel and park opened well in advance of deadline and hosted ANZAC Day centenary commemorations on 25 April 2015.

 

What the judges said:

Unique engineering solutions were required to construct Arras Tunnel, which takes state highway traffic beneath Pukeahu National War Memorial Park, so it can withstand a potential 1-in-2500 year earthquake.   The tunnel is part of a 300m long cut and cover trench which must contend with difficult land formations, high water table, huge seismic-induced soil pressures and a historic sewer.

The design solutions to overcome these challenges involved substantial and innovative use of concrete – some 7,500m3 in total.

Concrete was used structurally and symbolically as a key element to ensure the longevity of the park and tunnel as a national commemorative site.  The work was successfully completed in a very narrow and busy traffic corridor alongside several other integrated projects.

The trench and tunnel is a raw and robust piece of critical lifeline infrastructure that co-exists sensitively with the surrounding memorial park.  The Memorial Park Alliance team can justifiably be very proud of this overall achievement.