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Take a seat

By Cannon Ivers
Digital fabrication offers opportunities to create complex forms, but it also puts power back into the hands of the landscape architect.

The process of shaping objects aided by computer technology is not a new phenomenon. The automotive and nautical industries have been doing it for decades and architecture practices are readily embracing the technology to push the boundaries of production beyond the output that traditional methods could achieve. The landscape profession, however, has been slower to embrace digital fabrication. There has been a steady and gradual integration of the use of 3D as a design tool to visualise and study a space, to critique and refine a design response, but there has not been a groundswell of practices that have gone so far as to use the 3D information to streamline the construction process and realise the forms on site.
 
In this article, I will explore a series of projects that showcase the potential of digital fabrication in the realm of landscape architecture, highlighting the positives of the technology and where it has been used in preference to traditional approaches.  Through these exemplar projects, I will explore topics such as the fabrication process, materiality and contractor knowhow with the aim of demystifying the process and elucidating the tremendous possibilities that this technology affords. This, I hope, will encourage designers in organizations ranging from large practices to boutique studios to delve into this process in order to push ourselves as designers into a new era of creative expression.
 
Piazza Gae Aulenti is a public commercial space in Milan designed by AECOM and local Milanese practice LAND Milano.  The most notable feature of the scheme is a sculptural seat, encircling a 60m diameter reflecting pool in the heart of this prestigious mixed-use development. AECOM developed a modular system of seating elements, providing a series of ergonomically different components, which would be seamlessly fused together with a sophisticated transition module.  
At the schematic design stage, the AECOM team colour-coded the entire sculptural bench to illustrate the different modules and their overall arrangement, and then used CNC (computer numerically controlled) technology to create 1:20 models out of high-density foam to communicate the options to the client. This made it possible for the client to physically study and assess the design, ask informed questions and subsequently, make confident decisions predicated on the quality and accuracy of the physical models.
 
Once the design had been agreed with the client, LAND Milano, which is the leading landscape architecture practice in Italy, took AECOM’s fully detailed design information and associated 3D models and optimised them for construction through coordination sessions with local fabricators and engineers in Milan. The final sculptural bench is made from seven different pre-cast modules that were crafted using 3D software, before using CNC to create a timber mould to cast the final smooth white concrete components. 
 
It is evident from the quality of the finish that the contractor was conversant with CNC as a process for creating complex and sophisticated concrete work. The standard seat modules measures 1.5m (l) x 1.35m (w), with the larger transition modules reaching 2.2m (l) x 1.35m (w). The average weight per module was 2.5 tonnes. Due to the weight and the inherent constraints of this being a podium landscape, circular voids were added to the mould to reduce the load. The finished seat is both elegant and impressive, with a feminine sensuality that seems to encourage public displays of affection; or maybe that’s just the nature of the Italians. 
 
At LDA Design we explored a similar modulated system for a project in Mumbai where a sinuous seat was conceived as a symbolic ‘thread’ to visually stitch together a three-storey marketing suite, drawing inspiration from the rich textile heritage of India. After modelling the seat in Rhino as a series of standard modules with sculpted transitional pieces, our team of designers contacted the Rhino support team. They sourced a fabrication specialist in Mumbai who was au fait with CNC fabrication to deliver this signature element of the project. The specification for the seat was granite, but due to weight restrictions, the modular seat was fabricated out of glass reinforced plastic (GRP) and made to look like granite.  In this instance, the use of the 3D information afforded the design team a degree of confidence and control over the completion of a project that was 4,500 miles away without costly flights and the consequential contribution to climate change. This process will inform the construction of the final seating elements, which will be delivered in granite for the permanent residential development.
 
Closer to home in the UK, an ambitious project in Liverpool, which was awarded both the RIBA CABE Space Public Realm Award and Landscape Institute Honour Award in 2010, used extensive digital fabrication to complete the scheme.  Conceived by AECOM as a series of folded planes with granite seating terraces and steps overlooking a new canal link, Pier Head pushed the boundary of CNC technology. The most striking element of the scheme is the languid and beautiful transition from the granite seats to the steps that make up the level change for the plaza. Interestingly, using the digital fabrication process allowed the designers to integrate anti-skateboarding components in the granite seating modules to create a robust and elegant solution, in contrast to a retrofitted steel element tacked on as an apparent afterthought.
 
James Haig Streeter, design practice director at AECOM, explained the digital fabrication process like this; ‘Today’s typical design process is a curious thing, with the act of making being divorced from the act of conceiving to the point where some would say “design” only really happens at the beginning of the process; with the majority of effort being “documentation”. By contrast, the use of CNC is a bit like “digital craftsmanship”, enabling the designer to maintain control of complex design elements right to the point when the stone is cut, just as the architects of historic buildings once did.’
    
Early on, AECOM consulted Marshalls about selection of the stone. During this process, the design team was informed that Marshalls’ Chinese stone supplier was able to offer CNC cutting, which it had used for the Beijing Olympics. This opened up design possibilities, as it meant the team could design stone seating elements with complex surface geometries, without adding a great deal of extra cost. The construction documents, therefore, had both ‘traditional’ plans and sections, which were used to accurately lay out the different stone pieces, and also 3D views taken from the Rhino model. AECOM provided the digital 3D information to Marshalls as templates for cutting and then Marshalls took responsibility for modifying the files to add in joint tolerances and other installation-related information. The Rhino model had to be exported to a format that the CNC router could use; basically converting the 3D surface geometry into a series of closely spaced sections, which the CNC router traced to create the desired forms. Once cut, the stone was given a flamed finish by the stone cutters before being shipped to the UK for installation.  
 
I asked James if he had considered other materials. ‘As Pier Head is a UNESCO World Heritage site, the use of natural stone was the only real option,’ he said.  ‘Granite and sandstone were traditionally used on site but sandstone wears badly due to the wet site conditions. The colour of the seating is intended to closely match sandstone, with the durability of granite.’  For a project with such an important setting, the expertise of the supply, fabrication and implementation teams was vital to its success. According to James, the stone supplier Marshalls was knowledgeable enough to guide the design team, although all the cutting was undertaken by Marshalls’ Chinese stone supplier. Marshalls told AECOM that Pier Head was the most complex project it had ever been involved with; a combination of aligning complex, sinuous forms, which had low construction tolerances for error – typical joint widths were designed to be just 6mm. Marshalls’ reward came in 2010, when the project won the UK’s National Stone Award.
 
I asked James about the economies of scale with a project like Pier Head. Was it more cost effective to use CNC fabrication, I wondered. ‘When it comes to complex forms,’ he said, ‘CNC is typically considered cheaper than traditional methods for the simple reason that a robotic CNC machine can work 24/7. As a human stonemason can’t, the savings come from production time, enabling orders to be processed faster. That said, the stone is still finished by hand.’
 
Across the Atlantic in Cambridge Massachusetts, landscape practice STOSS has rejuvenated a threadbare space at the heart of historic Harvard University. In close proximity to the Graduate School of Design (GSD), the square consists of a simple plane of well-executed concrete planks, acting as a platform for a collection of beautifully crafted timber and concrete benches: an outdoor gallery of sorts. Similar to the Milan project, in this space the humble bench becomes the pièce de résistance in the form of an artistic, cutting edge and evocative art piece that people just happen to sit on.
 
Erik Prince, a graduate of the GSD and the project leader for STOSS, explained, ‘Originally, we explored options for constructing the benches out of Corian and even fibreglass. However, it became clear that those materials would not stand up to the fierce winters and the inherent wear and tear that the benches would be exposed to. Timber was selected, which has now weathered beautifully, providing a warm patina that catches the fading light.’
 
The majority of the benches are constructed out of timber, measuring up to 6m in length, but there are also large concrete forms that twist and contort from seat height up to chest height to allow the integrated wayfinding map to be easily read. These elements also double as crash barriers and bike stands and have to satisfy more structural requirements. These, too, are executed with panache and flair, acting as a foil for the traditional neo-Georgian architecture of the surrounding Harvard campus. The benches, with a total of seven different permutations, give visitors the opportunity to occupy the seat in a variety of ways, providing an added dynamic and energy to the space.
 
Prince explained the design process to me, ‘We used Rhino to push the iterative design process, producing multiple concepts and geometries, all of which were 3D-printed.  We used Grasshopper as a time-management tool to take the overall “skin” geometries from the Rhino model into CAD plans and sections, and for the arraying of the wood slats.’ What was the difference in the fabrication process between the timber and the concrete, I asked. ‘Concrete is a much more natural material for complex geometries,’ he said. ‘Producing the mould is easy with 3D printers, and concrete cast naturally to a sturdy mould. The trick with concrete is to get a constant finish, free from any pockets. With wood, there are still good contractors out there, but the trick was to get one that has the sources of wood readily available; dried and in stock.’  
 
The contractors on this project had never attempted, let alone completed, such tricky geometries. They used their own in-house 3D software and moulding printing (usually used for casting traditional detailed banisters/columns etc.) and adapted it for something more custom-made and contemporary. Serendipitously, the woodworkers were busy on Renzo Piano’s renovation of the Fogg Art Museum at Harvard. The contractor was using the best ‘temple’ grain Alaskan yellow cedar and had an overstock of this particular wood; which is the hardest known cedar in the world and historically used by the Japanese to build temples. Prince said, ‘Normally to specify Alaskan yellow cedar is very suspect in terms of sustainability because this wood is beautiful, but very pristine, old-growth wood, and cutting down old-growth forest in Alaska for some benches doesn’t sit well with most landscape architects. For us, 
we thought it was already there sitting in a shop so why not, plus our timescales were very quick.’ Stoss provided 3D models to the concrete and timber contractors, both of which then created their own models to understand the detail for coordination and software issues – neither used Rhino. The Stoss 3D models communicated the design intent, but traditional 2D drawings were used for coordination.
  
These case studies paint an exciting future for the landscape profession. Through the use of 3D modelling and digital fabrication, designers can continue to redefine the aesthetic of contemporary landscape architecture. This approach to the design of space and objects is still in a period of experimentation, but it is a territory, I believe, that is giving way to true innovation. With the coupling of imagination and technology, we as designers should be entering into a chapter of iterative design on a par with industrial designers, where we test, critique and refine our designs through the use of physical models churned out with the help of these fabrication tools. In closing, the limitations on what can 
be fabricated are dictated only by how conservative we are with our creative intellect and imagination.
 
Although the majority of the examples I have put forward have used Rhino as the modelling software, other software programs can also be used to great effect. Once the digital model is complete, there is a CAD/CAM software that converts the digital information and prepares it for use with CNC milling machines. This is traditionally carried out by specialist model makers and contractors, but leading education facilities have CNC machines for student use, where they are able to understand firsthand how to convert the information and finesse the machinery. Rhino support is a great starting point for anyone interested in pursuing this technology. Additionally, there is a knowledgeable online community that can readily be reached from the Rhino website at www.rhino3d.com.

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