Sculptor: Scott Sculptures
Structural Engineer: Jacobs
Steelwork Contractor: S H Structures Ltd
Main Contractor: S H Structures Ltd
Client: The Helix TrustA pair of 30m high tubular steel framed horse heads, known as The Kelpies are one of the final elements of The Helix Project, a scheme that has transformed a swathe of land between Falkirk and Grangemouth into a vibrant park with its own lagoon, outdoor events space, and a new turning pool and lock for canal boats.
As The Kelpies are an important centrepiece of the project, the client partners, Falkirk Council and Scottish Canals were always keen to have a major and iconic piece of public art and consequently Glasgow-based sculptor Andy Scott was approached.
He was commissioned to design an artwork that would reflect the scale and scope of the project. His choice of two steel framed equine heads initially had mythical associations, Kelpies being supernatural water horses of Celtic folklore, but as the project developed his inspiration came from heavy working horses such as Clydesdales.
“These horses played a vital and significant role in Scotland’s industrial revolution, such as pulling barges along the Forth & Clyde canal, next to which they now stand,” says Andy Scott, Project Sculptor.
Mr Scott has a long-standing connection with steel and it is invariably his material of choice for artworks. Normally he undertakes the manufacture of his pieces himself, but producing two 30m high sculptures needed a more collaborative approach with the structural engineer and steelwork contractor.
The Kelpies are made up of three elements – the primary frame, the secondary structure that extends from the primary frame to support the external skin and the stainless steel cladding that forms the skin itself. At tender stage, the secondary structure was formed by horizontal steel plates acting as diaphragms.
Jacobs and S H Structures together value engineered the original design and came up with a revised concept that brought savings of around £750,000. The new design replaced the original horizontal plate for the secondary structure with steel stubs, enabling the primary frame to be standardised and fabricated from 323 x10 CHS Celsius tubes.
The project team produced a Kelpies BIM model that was used to exchange information between the consultants, the checking engineers, the cost consultants and the sculptor.
“The ability to produce a snapshot of any given area of the structure enabled Andy Scott to see how his original concept was being developed,” says Tim Burton, S H Structures Sales and Marketing Manager.
Once the primary frame was modelled the secondary steelwork, which mostly consisted of smaller 139 x 5 CHS Celsius tubes and supports the stainless steel skin cladding, was added. After the model was completed nearly 2,000 individual fabrication drawings were produced.
“We fabricated as much of the steelwork offsite and brought it to Falkirk in the largest transportable sizes,” explains Mr Burton.
The primary main frame is made of sub frames that weigh up to 10t and have maximum measurements of 4.5m wide x 12m long.
It was impractical to trial erect both heads complete, but adjacent sub frames were matched to ensure a first time fit could be achieved on site.
As the bulk of the fabricated steelwork had been stored close to the site the lifting of the first sections started as soon as the foundations were complete. Due to the detailed modelling process, accurate shop fabrication and trial assembly, the structures went up quickly.
The various elements were predominantly bolted together with some welding on site required, although the design process ensured this was kept to an absolute minimum. The primary frames rapidly took shape and very soon the secondary steelwork was being added.
Some of the final items to be erected were the most complex, such as the ears, noses and jaws. They arrived on site fully assembled and were clad before being lifted into place.
Using Tekla software, S H Structures was able to locate the optimum lifting points and determine the correct sling lengths for these complex shapes. This information was invaluable to the site team, as physically locating these points on site would have proven to be difficult.
Early in the design process Andy Scott had produced a pair of tenth scale models to provide the team with something physical to work from. Once the steel frame had been modelled one of the biggest challenges was scaling up the method of creating the skin cladding.
The skins of the models were created by carefully welding together hundreds of individual small plates. Creating something ten times this size in 6mm thick plate needed a different approach. Initial concept designer Atkins developed a solution that still gave the appearance of the heads being clad with smaller plates when viewed from a distance. They achieved this by proposing the use of much larger panels that were pre-profiled by laser to achieve the desired effect.
“The geometry of the sculptures was extremely challenging, especially as we had redesigned the frames but kept the cladding system unaltered,” says Tim Roe, Jacobs Project Engineer. “This meant all of the steelwork had to be designed and fabricated to connect to predefined points for the cladding.”
The Kelpies along with the associated landscaping and canal works were officially opened last April. As Mike King, Helix Trust Programme Director says: “The project has dramatically transformed an area of under used land into a superb visitor attraction for the benefit of Scotland.”
Two shimmering steel horses heads, fully 30m high, required considerable engineering finesse to realise the sculptor’s vision. A tubular steel frame supports this most complex and delicate sculptural form.
Recognised internationally as probably the finest equine public artwork in the world, The Kelpies attract global visitors to Falkirk.