Halo is a kinetic sculpture located within a small park in the Central Park “urban village” development in central Sydney (still under construction in 2013). It has three components: a 13 m high silver mast which leans out at an angle; a 6 m long silver cantilevered arm which is attached to this mast; and a yellow carbon fibre ring—the halo—which is 12 m in diameter and pivots upon this arm. The arm and ring rotate on a slightly tilted axis in response to the kinetic energy of the wind. This rotation, which is almost frictionless, is made possible by a tiny ceramic ball bearing the size of a marble that is situated within the top of the mast. The artwork is intended to remind observers of the rhythms of the natural world and provide a space for calm pause amidst the hectic activity of the metropolis. It exemplifies the artists’ long running aspiration to create public art works which are “collaborations with nature,” as its passive kinetic form evokes the variability of the wind’s energy. Despite its scale and the rigidity of its parts, the work is finely balanced and exhibits a remarkable fluidity of movement. Its success in this regard is attributable to the involvement of a large team of specialist designers, fabricators and engineers with expertise in carbon, mechanical, wind and structural engineering.
AIMS
Cultural
Visual/Aesthetic: Halo was commissioned as part of the Central Park public art strategy – which was created by artists Jennifer Turpin and Michaelie Crawford. Thus the artwork had to align with the objectives outlined in that strategy [insert hyperlink to the profile of the strategy]. In sum, the strategy is concerned with commissioning public art which enriches the site (and the city) aesthetically and culturally, gives expression to the heritage of the site, and highlights Central Park’s progressive approach to sustainable building, design and energy use. A partial explanation of how the work is responsive to these objectives can be found on the artists’ website:
Inspired by the history of the site itself, Halo draws upon the language and processes of the old brewery. Giant, circular brewing-vat support structures combine with the endless stirrings of brewing alchemy and the tipsy effects of beer to inspire sculptural form and fluid motion. At the heart of Central Park’s public domain, Halo’s floating, encircling motion draws us inward and gestures outward to the space and energy of the environment beyond.
Turpin and Crawford were also interested in creating a work that could become a site for contemplation and focused attention within the fast-paced environment of the city, and to “shift attention from urban rhythms to natural rhythms.” Further, as stated in an interview, the work “seeks to hold attention through movement, to focus attention on movement and to the source of movement.” Conceptually, therefore, the work is in some ways less about appreciating at an aesthetically appealing object, and more about inviting viewers to be conscious of the pace and pulse of their immediate environment.
Innovation/Risk: There were significant technical risks to negotiate to ensure that the work had to be stable, durable, safe and able to withstand high winds. The engineering problem-solving required to address these requirements could potentially undermine the aesthetic attributes of the original concept.
A further risk lay in the location of the work, in the midst of high rise buildings that dwarf it in scale and create a lot of competing sources of visual stimulation.
Environmental
The work was intended to contribute to the Central Park development’s aim to foster eco-sustainable practices, and address the environmentalist concerns articulated within Central Park’s public art strategy.
The artists sought to draw attention to the somewhat intangible and invisible phenomenon of air and find a form that would provoke observers to apprehend that element in a new way. This required the artists, designers, fabricators and engineers to analyse how the wind behaves, and collectively work towards maximising the potential for the structure to interact kinetically with the types of wind it would be exposed to.
OUTCOMES & IMPACTS
Cultural
Halo is a highly refined structure and when viewed from most angles the yellow ring appears to float as if it is only resting gently on the cantilevered arm. This was achieved because the steel connections between sections were designed to be as unobtrusive as possible. The structure has been built to withstand extremely high winds (at which point an hydraulic braking system comes into play), yet be responsive to breezes as gentle as 2 km/h. This sensitivity was made possible by tapering the thickness of the ring: the changing width and hence surface area of the ring’s circumference means that it is responsive to wind from any direction. The 12 mm bearing enables the arm to swing around three axes at once, and its off-centre pivot point means that the ring creates an arc that exceeds its diameter.
Halo was the recipient of the President’s Award at the 2012 Engineering Excellence Awards, Sydney, which testifies to the engineering achievements that underpin the kinetic capacity of the structure. The success of the work can in many respects be attributed to the dedication and ingenuity of the engineers involved: it is as much an engineering achievement as an aesthetic achievement. The original design provided by the artists was extremely simple, and it was the engineering expertise that made it possible to transform that design into a structure that is strong, light and has great fluency of movement. Thus Halo can be understood to be a highly successful synthesis of a minimalist aesthetic with cutting edge lightweight materials and innovative carbon fibre, mechanical, structural and wind engineering. The sophistication of this synthesis is somewhat demeaned by the artists’ reference to the “tipsy effects of beer” (an allusion to the heritage of the site as a brewery).
As the surrounding buildings are in various stages of completion, it is difficult to judge how well the work inhabits the cityscape that surrounds it. However, when observed from close by it has an impressive scale. Its placement within a grass park means that it is anchored beautifully against the strict geometry and reflective glass surfaces of the high rise buildings that surround it, while at the same time, the metallic smoothness of its surfaces and the use of stainless steel means that it seems right at home within this location.
Social
By the time the Central Park development is complete the park in which Halo is located will be an oasis of sorts in an extremely busy mixed-use precinct. Halo certainly provides a restful focal point and contributes greatly to the ambience of that park setting.
Economic
The artwork is noteworthy for the size of the team that made it possible and the degree to which the artists’ practice in this case is immersed within corporate models of ‘project delivery’. It also raises interesting questions about the role of major public art projects in commercial developments: is its aim to be a counterpoint to the accelerated and expedient activity of the city compromised by the fact that offers aesthetic enhancement to a profitable enterprise within the city?
PROJECT DELIVERY
Halo is among several pieces of public art that have been and will be commissioned for the grounds of Central Park, a large, mixed-use “urban village” development that is under construction in the heart of Sydney. The Central Park development has invested in sustainable technologies and committed to the City of Sydney’s Sydney 2030 vision of dramatically reducing greenhouse gas emissions and increasing the use of renewable energy sources. Halo artists Jennifer Turpin and Michaelie Crawford were the authors of the public art strategy which has been adopted by the Central Park developers, and environmental values are also enshrined within this strategy. This strategy provided the context for the development of Halo.
The project took three years to come to fruition, requiring substantial research and intricate design and engineering work. Tests were conducted to ensure the small ceramic bearings could perform under the weight of the structure, and with maximum movement. The engineers created several scale models which were tested in wind tunnels at CPP Wind Engineering facilities in Sydney, while they also undertook cyclic load tests at SPFX Australia to ensure that the bearing could bear the load created if the ring is rotating at high speeds. Customised software was created by CPP engineering, and a fully assembled model of the work was tested in real wind conditions at the site of the fabricator, Innovation Composites, in Nowra. The findings of this test led to the recalibration of the software by CPP engineering. In addition, at the end of the design development stage and prior to fabrication the artists had to revise the design of the cantilevered arm to ensure that the work was structurally sound. The ring is made from lightweight carbon fibre, the ball bearings from immensely strong PSZ ceramic and the steel components from duplex stainless steel 2205, which is characterised by strength and longevity.
The project stalled for eight months about a year into the project, when it was still in a design phase, at the request of the clients who commissioned Halo. This loss of momentum and the uncertainty it generated created serious problems, particularly because the project depended upon the collaboration of so many parties. As the artists stated in an interview with the author:
Stopping the project was a problem because none of us knew when work would start up again. It made it difficult in terms of securing/keeping the preferred contractor and work schedules for all involved. The artists for example could not take on new projects because they needed to be available when Halo started up again.
The team also faced problems that arose from the fact that the client retained control of the payment of contractors and subcontractors. This problem has implications for any large scale public art project in which many parties are involved:
The method of procuring the artwork meant payments were slow and cash flow problematic. The procurement method was similar to an ‘open book’ arrangement where the client signed off on all the contracts and controlled payments to individual contractors and consultants working on the project. A preferred alternative would be for the artists’ project manager to have control over a given budget so as to be in a situation to pay contractors and sub-contractors and consultants in a timely way.
In response to the question “were any lessons learnt that could improve the delivery of such projects in the future?”, the artists responded with the following points:
- Have tighter contractual arrangements in place for payment scheduling from client or give more control to the project manager to pay subconsultants and subcontractors directly in order to ensure better cash flow and smoother. This will make the project more financially manageable for all subconsultants and subcontractors involved in the projects.
- Have provision in the contract with the client for a restart up fee in the event of the project being delayed or stalled by the client.
- Clarify artists scope of work at all stages in the project. Consider such matters as the time and cost involved for the artist/s in producing material for media releases, photographic documentation for media and opening launch. Ensure if such work is to be done by artists that payment has been discussed prior with the client.
IMPACTS OF ARTWORK PRODUCTION
The design was highly minimalist, and exploited materials that were lightweight and structurally efficient. Little future maintenance is expected to be required.
SOURCES
Cambourne, Keeli. “A New Spin on Public Art.” The Sydney Morning Herald, September 2, 2012.
Cameron, Danny. “Making the Impossible Possible.” Engineers Australia, November 2012, 38-48.
Turpin, Jennifer, and Michaelie Crawford. “Halo.” Turpin + Crawford Studio: Collaborations with Nature. http://turpincrawford.com/project/halo (accessed March 12, 2013).
Turpin, Jennifer, and Michaelie Crawford. Interview by authors, March 11, 2013.
Turpin, Jennifer, and Michaelie Crawford. “Making Halo 5-Web-Mobile.” Video presentation. http://vimeo.com/47648401 (accessed March 11, 2013).