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Frozen asset

Structures Halley 6 research station

For the first time, British Antarctic Survey is using the private sector to design a research station.

Andrew Mylius discovers why.

Within the next decade one of humanity's remotest outposts, the British Antarctic Survey's (BAS) Halley 5 research station, will fall victim to the very thing it was built to investigate - global warming. Part of the 150m thick Brunt Ice Shelf to which the research station clings is set to break off, or calve.

The mass, measuring between 600km2 and 1,200km2 will then rapidly disintegrate into a treacherous sea of icebergs.

To get its 70 strong crew of scientists out of danger's way well before calving takes place, and to ensure that its internationally important meteorological and climatological research keeps going without interruption, BAS is accelerating plans to build a new Antarctic station, Halley 6. Last month three designs were selected from 86 entries submitted to a competition.

The three UK-based engineerarchitect pairings - Expedition Engineering with Michael Hopkins, Buro Happold with Lifschutz Davidson and FaberMaunsell with Hugh Broughton - now have until September to research the Antarctic environment and evolve their concepts. Construction of the chosen design is scheduled for two short Christmas to late February windows, in 2006-07 and 2007-08, when BAS can get its supply ship to the Brunt Ice Shelf. The $35M contract will be let on a design and build basis, with about $30M left for construction after transportation.

In organising a design competition, BAS has departed from tradition. 'We built Halley 1 in 1956 and have done another four since then. We've done a lot of the design work in house and gone to an architect only for detailed design, ' says BAS Halley 6 project manager and civil engineer Karl Tuplin.

Although BAS has enormous expertise in living in a -50degrees world of snow, ice and howling wind, its own designs tended toward 'extreme functionality', admits BAS head of physical sciences Mike Pinnock, a veteran of three seasons at Halley 3 during the 1970s. This time around, BAS wanted to see what private sector thinking would bring to the Brunt Ice Shelf.

The first four Halley stations were placed directly on the ice shelf 's surface and were quickly buried in Antarctica's 1.5m annual snowfall. 'If BAS had a motto it would be 'everybody digs', ' deadpans Pinnock. Halley 5 was equipped with jackable legs to keep it above ground level, although raising the structure is a full two day operation.

Pinnock estimates that the station's scientists spend about 40% of their time engaged in 'base duties' - anything from snow shovelling, through repair and maintenance of structures, equipment and infrastructure, receiving supply ships, to cooking and cleaning. The 60% of time spent setting up research equipment and running experiments is far from cushy.

But with Halley 6, BAS is setting out to reduce the time spent overcoming the 'challenge of survivability' by making the station building itself far more user friendly and comfortable, says Tuplin. 'Achieving that means we can allow more time for science, or alternatively we can reduce the numbers of people stationed there, ' says Pinnock.

'That reduces running costs and environmental impact.'

BAS has avoided detailed specifications for Halley 6, preferring to set a performance brief around particular challenges.

Tuplin has urged designers to look at new ways of using tried and tested technology, rather than bespoke solutions. 'If anything goes wrong, people out there are on their own, cut off from the rest of the world. They have to be able to fix things themselves.'

As well as being able to jack accommodation units up above each year's snowfall, BAS wants Halley 6 to be relocatable, as ice making up the Brunt Shelf flows 400m a year. Halley 5, completed in 1991, is founded on legs that, with the accumulation of snow, have effectively become deep friction piles, rooting it in the ice.

BAS will be looking to move Halley 6 up to 10km, two to three times over its life. This has to be achievable using BAS standard 20t Caterpillar dozers.

All supplies, construction materials and equipment for the Halley research station are landed during the Antarctic summer on sea ice bounding the ice shelf proper. This has a nominal bearing capacity of 20t. Tractors used by BAS weigh in at 10t and sleds 3t, leaving only 7t for cargo.

Halley 6 will have to be built from small, lightweight components.

To keep Halley 6's environmental imprint as low as possible BAS has given designers a 125kV limit for energy generated from fossil fuels. Any additional power will have to be generated using renewable energy sources.

'But the biggest constraint is the programme. We have little more than four months construction time, spread over two years, ' says Tuplin.

FaberMaunsell/Hugh Broughton

Lightweight is FaberMaunsell's watchword.

As well as reducing weight to a minimum to transport materials across the sea ice, lightweight buildings will be easier manoeuvre across the Brunt Ice Shelf.

To this end, the research station will be composed of a number of small semiautonomous accommodation units linked by insulated umbilical cords to a central work unit. Plant will be housed in small external pods. Designs have been vetted for Antarctic conditions by FaberMaunsell's US sister company DMJM, which has designed many of the US research stations.

'These small, lightweight modules form a kit of parts that are very flexible and can be arranged in a number of different ways to suit BAS's changing needs, ' says FaberMaunsell project leader Peter Ayers. 'It's a fleet of foot, flexible model.'

FaberMaunsell is opting to lift structures clear of new snowfall using inflatable airbags and scaffold platforms - an established BAS lifting technique.

Its design for Halley 6 spreads load over a far larger surface area than the other two shortlisted designs, with large numbers of skis. 'We think that bearing capacity of snow is quite low, ' Ayers notes.

Expedition/Micheal Hopkins

'This building needs to move up and across the ice, ' says Expedition's project engineer Ed McCann. 'You can treat it two ways - as an animal that walks away from danger, or as a plant that is reliant on a gardener to move it.

This building is an animal.'

Expedition's Halley 6 will sit on four to six pairs of legs with large, spreading feet which will work synchronically to lift and 'walk' the building to new locations.

Each leg can be extended and retracted by its own hydraulic jack. And one leg in each pair can be moved forward or backward along a rail by a third jack. To raise Halley 6, snow will be packed under each foot until all feet have been brought up to surface level. 'It'll then move forward like someone using a zimmer frame, ' McCann explains.

The building itself is modular - McCann envisages the 80 to100 components needed for each building being prefabricated in New Zealand before shipping to Antarctica.

Structural strength will come from a central longitudinal truss and robust external, clip-together cladding panels, creating loadbearing 'strong walls' capable of spanning between legs.

The external surface is minimised to keep heat loss through the building's skin low, and the whole will be clad in a triple layer ETFE cushion, giving Halley 6 its very own puffa jacket.

Buro Happold/Lifschutz Davidson

Buro Happold is equipping each of its Halley 6 live-work units with 16 up-down only legs. Powerful 'Brunelian' screw jacks will enable adhesion between its snow shoes and the ice to be easily broken and help get all eight feet to the same level, says team leader and Buro Happold partner Ian Liddell.

Accommodation is provided above a trussed spine, into which plant is slotted.

The whole is cocooned and protected from relentless wind-blown snow by an ultratough, ultraviolet radiationresistant teflon-coated fibreglass windshield. This will be erected immediately on completion of the truss to give weather protection. Inside, insulation is 'bog standard', of the type found in industrial freezers, Liddell says.

The design's guiding principle is 'brutal simplicity, or it won't be built in time', he adds. Components will be prefabricated and, as far as possible, preassembled, with a high degree of standardisation.

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