Construction will start in about two months on a $1.5 million Lyttelton tunnel control building to replace the recently demolished original.
The original building, designed by Christchurch architect Peter Beaven and built in 1964, was a category-1 heritage building.
The new building, as seen in the concept drawings above, was designed by Wellington firm Architecture Lab, and will be built closer to the tunnel, in an area less prone to rockfall.
The NZ Transport Agency's Canterbury/West Coast State Highway Manager Colin Knaggs says the new building has been designed first and foremost as a purpose-built facility to manage the operation and maintenance of the Lyttelton Tunnel. It will be built closer to the tunnel, in an area at less risk from rockfall.
"It is not intended that the building replicate the old structure but rather that is express some of the qualities of the original 1964 Peter Beaven-designed building, such as the strong horizontal lines and the appearance of it floating."
Knaggs says the new building is essentially three primary blocks, the largest dark grey-coloured block being partially clad with concrete panels to anchor it to the landscape.
Dan Popham of Architecture Lab says this block has a colonnade of concrete columns along the access path reflecting some of the rhythm and building elements of the original tunnel control building, while also providing a degree of protection from any potential future rockfall.
"The remaining two blocks adjacent to State Highway 74 are of a lighter weight construction with a cantilevered deck to the north and operator room to the west giving the building a sense of floating.
"The whole building is cut into the hillside and orientated to align with the existing landscape contours to minimise its impact and dominance on the state highway."
Knaggs says the building will be constructed to 180 per cent of the Building Code to ensure it can continue to operate in the aftermath of any future earthquake.
"The NZTA made the decision to have the original building demolished only after it had completed a full investigation of all feasible options to repair it. The cost of repairing the building was $3.5 million more than building a new fit-for-purpose one."
Construction of the new $1.5 million building is expected to begin within the next couple of months and it is scheduled to be completed in time for Lyttelton Tunnel's 50th anniversary celebrations in February next year. "The contract to build the new facility is out for tender. This is expected to be let early next month."