At its opening in 1977, the international terminal had a total floor area of slightly more than 12,000m². Today it’s about 100,000m². The annual passenger throughput is currently 11-million, expected to rise to 25-million by 2025. That’s in 17 years’ time. In three years’ time, it will have to be able to cope with the rugby World Cup. And by February 2009, it has to be ready for the first gigantic Airbus A380.
Steltech portals stride down the runway
As the Airport’s Master Plan is rolled out, the planners have had to contend with more than just the rising numbers of tourist visitors. When airport security became a critical issue, the Civil Aviation requirement was that all arriving and departing passengers should be kept separate within the airport terminal. More than 30 proposals were intensively studied until the best solution was identified: add a new floor to the existing 40 year old Pier A. This was accomplished while the airport was kept running and more than 17,000 international passengers moved through the pier every day.
Now it’s innovation in large jetliner design that’s testing the resilience of the Master Plan, and the Plan in turn demands flexibility of construction; speed and adaptability become critical when gate closures based on plane arrivals necessitate stop-start building during intervals. In such demanding conditions, structural steel comes into its own. Whole structural units can be pre-assembled in the workshop before being delivered to the site, often during odd hours chosen for safety, where they are quickly erected with no interruption to airport operations.
It’s highly specialised work that D&H Steel Construction Ltd has been doing at the Airport for the past 18 years. Managing Director Mike Sullivan says: “Steel is quite accommodating logistically. It doesn’t need a large on-site workforce. and it doesn’t take up space with temporary works. And, most important, today’s steel construction methodology makes it possible to micro-manage the all important factor of safety. When we were erecting the roof, for example, we were able to hoist and bolt four rafters a lift – that’s three bays at a time complete with purlins.”
Pier B is to be constructed in stages over the coming years to match air passenger growth. In its final configuration, it will be in the order of 360 – 400m long and just over 30m wide. In order to achieve predictable structural behaviour, it was necessary to design Pier B as a series of smaller, independent units, with seismic breaks running across the pier structure at intervals of approximately 120m.
The structural engineering company responsible for the design is Beca Carter Hollings & Ferner Ltd whose team is led by Richard Built. In his Design Features Report he says: “The structural system comprises a steel braced frame over the height of the building from ground floor to departure level. Structural columns are typically 406mm diameter concrete-filled circular hollow sections. Beams are a combination of rolled and fabricated “I” sections. The frame is braced in each of the principal orthogonal directions with 217 x 273mm CHSs arranged in a concentric ‘K’ configuration.
Project Director, Ted Senner of Hawkins beneath one of the two fixed links, which will ultimately be Gates 15 & 16
“Above departure level the roof comprises a series of portal frames spanning in the transverse direction across the width of the pier, with each frame positioned on the structural grid. In the longitudinal direction, the frames are braced on each elevation with diagonal bracing between the legs of the portal and also between the rafters across the roof. The portal frames are “I” section welded beams and columns fabricated from plate. Where the bracing is exposed at the departure level, it consists of stainless steel cable; otherwise it is a combination of steel angles and sections.”
Pier B is linked to the main international terminal building by a Connector, which runs diagonally over apron roads giving them a 4.5m vehicle clearance.
Travelators will be installed in the connector at arrival and departure levels.
The Connector makes it easy for passengers to transit from the expanded arrivals area of Pier A to the departure gates of Pier B without having to go through customs.
Projecting from the side of Pier B over the apron are two fixed links which will ultimately become Gates 15 and 16. Each gate has two airbridges and can handle an A380, or B747, or two smaller aircraft. This flexibility is known as MARS – Multiple Aircraft Ramp System – and the decision in favour of this option was taken after what Scott Logie, Beca’s Project Manager, called “some rigorous value engineering. Originally there were going to be four gates on Pier B – all capable of servicing Boeing 747s with two that could handle A380s. The value engineering work saw the four reduced to two but configured for MARS. This had to be accomplished within the original design and construction programme time-table.
“The ground conditions at Pier B required that a total of 86 concrete piles had to be driven. More will be needed if the Pier is extended to cope with rising passenger numbers. But adding structural steel, even when the pier is operating, will be straightforward. One really exciting innovation is that aircraft using Pier B will have access to our new ground power supply, which aircraft can access, obviating the need to use aviation fuel to maintain operating conditions while on the stand.”
Commenting on progress towards the handover date, Ted Senner, Hawkins Construction Limited’s Project Director, said: “The project’s on track to meet the deadline, largely because of the many years of experience among the key players. In total we’ve calculated that 575 tonnes of steel went into Pier B. If you collect trivia, that’s about the weight of one A380, fully loaded and fuelled (560 tonnes).” Then he quipped: “That’s close! If the pier were just the right shape it might fly!”
The mullioned glazing system rises to a height of 4.8m. Vertical truss cladding frames are provided around the fixed link structures
Engineering Manager Airfield and Terminals at Auckland Airport, Paul Duffy, says the Pier B development will be given a sustainability rating according to the American LEED system. ”LEED stands for Leadership in Energy and Environmental Design and is generally accepted as the international benchmark for the design, construction and operation of public and commercial buildings such as airports. Features include rainwater harvesting, solar water heating, photovoltaic solar panels and low energy lighting and signage to name but a few.”
