This is the third of a series about the five finalists for ASCE’s Outstanding Civil Engineering Achievement (OCEA) awards. Established in 1960, the OCEA Award recognizes a project that makes a significant contribution to both the civil engineering profession and society as a whole. The winner of this year’s OCEA award will be announced at ASCE’s Outstanding Projects And Leaders (OPAL) Gala, March 26, at the Renaissance Arlington Capital View Hotel in Arlington, Virginia. Today, read about the Halley VI Antarctic Research Station. –
Since 1956, the British Antarctic Survey has had a near impossible mission: carry out pioneering earth science research on the 500-foot-thick Brunt Ice Shelf floating in the Weddell Sea, in Antarctica, where temperatures plummet to -69°F, the wind reaches speeds up to 100 mph, snow levels change, and ice packs shift. The first 4 Halley bases, constructed over the last 59 years, became buried in snow and had to be abandoned.
Designed by AECOM and Hugh Broughton Architects, the Halley VI Antarctic Research Station is the first fully relocatable arctic research station in the world. Launched in February 2013, the futuristic, $43 million state-of-the-art research facility is segmented into 8 modules, each sitting atop ski-fitted, hydraulic legs designed to cope with rising snow. These legs can be individually raised to overcome snow accumulation, and each module can be towed independently to a new location.
Constructed on a floating ice shelf – where most buildings are rapidly buried and crushed by the annual buildup of snow and ice – the engineering design challenges were immense. Considerations included logistics; extreme cold, wind, and snow environments; snow accumulation; moving ice; narrow construction windows; environmental protocols; and very tight financial constraints.
The design of the station relies on tried and tested technologies, by necessity often applied in innovative ways. The design team collaborated with suppliers from the shipping, transportation, and aerospace industries to adapt and develop new products for incorporation.
ASCE News Associate Editor Doug Scott interviewed Peter Ayres, BEng, CEng, MICE, MIStructE, director of Building Engineering for AECOM and strategic development director of the Halley VI.
1. What is the most innovative or creative aspect of your project?
Halley VI has a unique and highly innovative way of prolonging its working life almost indefinitely in an environment which has seen four previous bases lost to the Southern Ocean, and a fifth threatened with the same fate. The station comprises a collection of linked modular buildings which are supported on hydraulically operated legs and giant ski foundations. The hydraulic legs allow the station to sit safely clear of the snow, and mean that the whole base can mechanically adjust to the ever-changing snow and ice movements. And, as the base drifts out toward the ocean, the modules can be lowered onto their skis and towed inland and reassembled in a new, safe location every 10 years or so.
These innovations mean that Halley VI can be positioned relatively close to the edge of the ice shelf, shortening supply routes and reducing energy consumption, but without the risk of being buried by snow or drifting away on a giant iceberg.
2. What was the biggest challenge?
The ice shelf is a truly extreme environment, thousands of miles from civilization. The sun does not rise above the horizon for 105 days during the austral winter and does not set for a similar period in the summer. Temperatures drop to -70º Fahrenheit and the site can be buffeted by winds in excess of 100 mph. Access by ship and plane is limited to a 3-month window from December to February. All materials and components required to sustain the existing base or construct a new base have to be dragged from a ship across fragile sea ice.
From the outset, it was clear to the design and construction teams that the site logistics would present one of the biggest challenges. The route across the sea ice to the ice shelf is a key bottleneck in the supply route both for construction and operation. Deliveries across the sea ice are by sled with an allowable load of six (metric) tons per sled. This places very onerous constraints on the size of elements which can be delivered to [the] site. However, the remoteness of the base is exceptional even by Antarctic standards, which means that severe restrictions are placed on the construction program and annual relief operations. It was, therefore, a fine balancing act to maximize the degree of prefabrication to minimize site activities while staying within the constraints of the supply route.
3. Did your project have any technical issues that you had to overcome? If so, what were they and how did you overcome them?
The design team needed to completely challenge all previous assumptions and intuitive knowledge about how buildings are designed when creating Halley VI. Nothing is done by accident; every design feature has a function.
For example, the station is arranged in a straight line perpendicular to the prevailing wind so that snow drifts form on the leeward side. This leaves the windward side free from drifts, reducing snow management requirements and creating a hard icy surface across which vehicles can easily move without hitting soft areas of snow.
All external doors are carefully positioned in areas where they will be kept free of snow through consideration of prevailing winds. But just in case of snow buildup, the doors all open inwardly into lobbies so that it is impossible to be trapped inside the station.
Cladding is a crucial element in the design of an Antarctic base. It needs to be erected quickly, safely, and efficiently while providing a robust envelope with resistance to the passage of cold air, moisture, snow spin drift, thermal shock, and high levels of ultraviolet light. After an extensive R&D [research and development] program, the Halley VI design team worked in collaboration with the supply chain people to develop an innovative cladding system formed from relatively lightweight fiber-reinforced plastic panels fixed on to the steel structure and joined with a neoprene rubber gasket. All windows, door frames, and other features which could be weak points in the cladding system were factory-installed during the manufacturing process.
4. What time and budget challenges did your project have and what did you do to overcome them?
The construction program for Halley VI was not like that of any normal project. Construction could only take place in 12-week summer construction windows; this was the only time that the site was accessible for a construction team. The successful delivery of the project therefore required meticulous planning, down to even the tiniest detail, so that the precious time on the ice could be optimized.
Almost all of the components were prefabricated off-site, as far as the logistical constraints would allow. The full-scale trial erection and testing of the modules was undertaken prior to shipping to Antarctica. These trials were essential to the success of the project, since it was possible to make modifications to the assembly process and replace defective components prior to shipping, so that on-site activities in Antarctica could proceed with maximum efficiency.
The components for the construction of the modules were delivered to Antarctica by ice-strengthened cargo ship and delivered on skis across the sea ice, in accordance with the original design concept. Assembly took place at the existing Halley V site over three 12-week summer seasons. Toward the end of the third season, when the outer shell of the modules was complete, the entire base was relocated approximately 10 miles to the new Halley VI site, where [the modules] were assembled together and leveled up on their hydraulic legs as one complete base for the first time, before final commissioning in the fourth season.
5. Sustainability is one of the 3 strategic initiatives here at ASCE. Describe how your project adheres to being sustainable.
Sustainability drives energy use at all levels of the design. But power and heat generation are truly life critical in remote Polar Regions. While renewable energy sources are available in Antarctica, the robustness of technologies is not yet sufficiently developed or proven to be relied upon at Halley. Therefore, in creating a more sustainable, environmentally friendly base, the priority for the design team was to minimize energy consumption. Key to this was to provide a well-insulated building enclosure and to achieve an optimum energy balance throughout the winter and summer seasons. In summer, temperature conditions are more favorable, but the number of residents on the base is significantly higher, so different energy demands prevail.
Consideration of the overall energy balance between heating requirement and electrical generation was the basis for the selection of [a] combined heat and power (CHP) plant. The CHP engines were selected to provide the best balance between summer and winter loads. The heating sources within the accommodation provide the correct mix of convective and radiative heating to optimize human comfort. Heat recovery on all ventilation air with demand-side control based on air quality monitoring [keeps] airflows at the most energy advantageous rates.
The combination of a well-insulated, sealed enclosure and good controls ensures efficient energy consumption around the clock. The addition of a vacuum drainage system with low-water-use equipment will result in a 50% reduction in potable water use compared [with] the current station. Simplified processes dramatically improve operation and maintenance procedures, reducing the numbers of staff needed to look after the station. Taken together, these measures result in an overall fuel reduction of 26% per unit area compared with Halley V.
Next in the series, read about the San Francisco–Oakland Bay Bridge New East Span