Pukeahu National War Memorial Park and Underpass (Arras Tunnel)

LANDSCAPING 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:

The significant and symbolic use of concrete in this redevelopment of our National War Memorial has resulted in a landscape that connects the existing National War Memorial to the Capital.

This 21,000m² park of boulevards and terraces sits atop the busy arterial roadway underneath and contains a broad mix of concrete form, texture and patterns that only concrete can make possible.

The quality of finish and attention to detail of the concrete elements blend with the other features and installations in this important place and helps create the transition from city to park.