Global Project of the Year: Halley VI Antarctic Research Station
Antarctic researchers spend months in total darkness and brave -55°C temperatures and winds in excess of 100 mph. Yet these hardy souls endure and thrive at the Halley VI Antarctic Research Station, a $42-million habitat constructed in one of the most hostile environments on Earth.
The sixth station to be built, since it began research in 1956, by British Antarctic Survey (BAS), Halley VI confronts the harsh conditions through an innovative design, the use of building components borrowed from other industries, and meticulous planning and prefabrication. Still, from conception to completion, the project took nearly a decade, due to an extremely short building season and limited accessibility.
"There's an old adage: A month spent properly planning a project will save you a year at the end of the project. In Antarctica, that's absolutely true," says John Hammerton, operations director with Galliford Try, the Uxbridge, England-based contractor tasked with building the 1,510-sq-meter station. "You have to put all your effort into the front-end planning and design and get that right."
To that end, BAS launched the project, in 2004, through an international design competition to find a fresh approach to station design through technological innovation and creativity, says Linda Capper, BAS director of communications. The competition drew 86 entries from around the world. "We expected to get a lot of interest, but the quality and variety of ideas that came forward through the first phase was astonishing. The competition clearly fired the imagination [of designers]," she adds.
After a year-long evaluation period—which included fully funding three finalists to travel to Antarctica and finalize their schemes—BAS awarded the design to a partnership between the London offices of AECOM and Hugh Broughton Architects.
"It was the most rigorous design competition you could ever imagine," says Peter Ayres, AECOM's project director.
Located atop the 150-m-thick Brunt Ice Shelf, the station needed to respond to the area's copious snowfall of up to 1.5 m per year. All the structures—the seven 152-sq-m, blue-clad modules, which house the bedrooms, generating plants and science labs, and the 479-sq-m, red-clad module for dining and socializing—stay above the ever-rising snow by perching on 4-m-high, 580-millimeter-dia stilted legs.
The modules stand in a line as if they were train cars and are linked to each other with flexible inter-carriage connectors, modified, in fact, from the rail industry. Orienting the 188-m-long linear "train" perpendicular to the prevailing winds keeps the blowing snow from collecting underneath the aerodynamic structures, says Michael Wright, lead engineer with AECOM. At the end of each winter season, the modules lie deep within a scoop-shaped trough.
But Halley VI has another trick up its sleeve to rise above the trough before the snowbanks get too deep: At the press of a button, a technician can raise, one at a time, each module's four circular, telescopic leg tubes via an integral hydraulic ram. A Caterpillar D5 bulldozer operator pushes and compacts the snow to create a new, higher base for the leg, which is lowered back down to meet the new surface. Once all the legs are lifted, the entire station is jacked up to its full height.
The previous station also was built on stilts that could be jacked up, but the process took two months and required a team of ironworkers to reweld the legs, once extended. "It was very expensive, not just to send people down but to accommodate them through the summer season," Ayres says. The new base takes just six days to raise using on-site staff.
But the cause of the previous station's failure wasn't the snow but its fixed foundation. Just like a glacier, the ice shelf travels up to 1,300 ft toward the sea every year, and Halley V eventually crept too close to the calving edge. To overcome this hurdle, Halley VI's legs are affixed with skis. When the base is in danger, modules detach and are pulled by bulldozers to a safe site, where the modules can be reattached.
The 3.9-m-long, 1.1-m-wide skis, sourced in Germany, double as spreader foundations. "They are very precisely designed with a slight [V-shape] on the underside" and rounded in front, to minimize frictional resistance when moving the 60-tonne to 200-tonne modules, Wright says.
A slot was built into the skis to insert a daggerboard in case the modules began to slide under heavy wind loads. “In actual fact, it hasn’t proved necessary to have those centerboards installed, because you get such a strong bond between the ice surface and the underside of the ski that the module stays firmly fixed in position,” says architect Hugh Broughton.
The base may not need to be moved for many years, but the procedure already has been tested successfully. The base was built next to Halley V to provide workers with accommodations during construction and then, after completion, towed about 10 miles to its new home. Halley VI's design life is 20 years, but its mobility and modular design could keep it in service 40 years or more, says Caroline Lewis, BAS logistics coordinator.
Each module's steel space-frame substructure helps combat stresses during movement. The steel superstructure attaches to the perimeter to maximize flexibility of interior spaces. Specially manufactured, high-ductility steel prevents brittle fractures in the cold climate. Blue modules measure 19 m long by 9.5 m wide, while the red module is 28 m long by 11.5 m wide.
Construction crews had a 10- to 12-week window to build on-site each year, due to dangerous weather conditions and accessibility issues. “It’s a difficult place to transport people to; it’s expensive, and once they get there its expensive to keep them alive, so you want to minimize the number of people on the ice,” Hammerton Says. "If we could have pre-engineered and manufactured [entire modules] outside of Antarctica, that would have been the ideal solution."
However, the idiosyncrasies of the Antarctic supply line stymied delivery of fully assembled modules. Icebreaker ships off-load cargo onto sea ice that forms each winter, usually 1 m thick. "We made it clear from the outset that there were severe restrictions on weight, and the designers were required to incorporate this into their designs," Lewis says.
Crossing the sea ice, each load could not exceed six tonnes—plus 3.5 tonnes for the sledge—or else crews risked breaking through the ice. Despite this limitation, Galliford Try maximized the modular, pre-engineered components by pre-assembling as much as possible in Cape Town, South Africa, while keeping each chunk below the weight limit.
Bedrooms, bathrooms, generators and control panels were configured and delivered in preassembled pods. Flooring and under-floor building systems were delivered in "cassettes" that were easily installed.
Crews performed on-site assembly using two lightweight Mantis 6010 30-ton crawler cranes. "[The cranes] could just do the maximum lift that we needed, and it was easy to separate the jib and the counterbalance off for transport across the sea ice but very quick and easy to put back together again," Hammerton says.
With such a short build season, all the preassembled components had to fit right the first time. To reduce risk of on-site problems, the project team test-erected steel and cladding for two modules in South Africa. It turned out one of the pieces didn't fit correctly on the red module, but "we could just take it back to the workshop down the road and fix it," Ayres says. "If that had happened in Antarctica, we'd have lost a year."
Upon completion in February 2013, the contractor had performed 250,000 worker hours without a recordable incident. "The implications of having an accident [in Antarctica] are far more serious than they would be elsewhere," Hammerton says. The spotless record was attained through meticulous planning, managing risks and fostering a spirit of teamwork and camaraderie among the workers, he adds. Workers were schooled on unusual hazards, such as snow blindness and whiteout conditions.
All new Antarctic structures, including Halley VI, are required to minimize environmental impact. Vacuum flush and drainage systems, similar to those found on ships and airplanes, help cut water usage by 50%, compared to the previous station's system. This tactic saves energy since all water used on the station is created by melting ice, a process which consumes fuel. Custom-made sewage treatment plants, also based on those used in ships, produces clean-water discharge via a membrane bioreactor and UV disinfection. Dry sludge is incinerated, and heat is captured and fed into the energy systems. The station's simplified processes require 10 fewer maintenance staff to operate. In all, the project uses 26% less fuel than the previous base.
The R65 cladding is formed by 230-millimeter-thick, closed-cell polyisocyanurate foam insulation ensconced between glass-fiber-reinforced plastic panels. Station residents requested ample windows, so designers borrowed designs from the aerospace industry. In the two-story social module, a large double-glazed window is filled with a translucent nano-aerogel to minimize heat transfer and maximize light in the summer. Other areas incorporated triple-glazed windows with plastic spacers between each pane.
Hospitality-like interior details provide a pleasant environment. "We imagined a day in the life of a scientist, from the moment their feet hit the carpet in the bedroom until the moment they go back to bed again," Broughton says. Lighting and colors were specially designed to overcome seasonal affective disorder during the months of 24-hour darkness. Even some of the wood veneers were specifically selected to overcome the sensory deprivation of Antarctica. “We chose Lebanese cedar veneer because it’s the only one that gives off a pleasant aroma,” he adds.
In some ways, the project resembles a machine more than a building. "Although expensive, it's a bit like a Formula One race car, where the innovation can feed down into the wider industry, especially over time and through mass production," Broughton says.
Project Team
Owner: British Antarctic Survey, Cambridge, England
Lead Design Engineer: AECOM, London
Architect: Hugh Broughton Architects, London
General Contractor: Galliford Try, Uxbridge, England
