Tube & Pipe
Tuesday | 11 September, 2012 | 8:51 am

Leaves of Steel

By Lynn Stanley

Architects turn metal tubes into wind-powered musical outdoor sculpture

September 2012- Perched on a slope of the Pennine mountain range overlooking the market town of Burnley in Lancashire, England, a tree “grows.” But unlike its organic counterparts, this tree is made up of approximately 3 tons of galvanized steel tubes crafted to capture and turn the region’s wind currents into a harmonic song that is sometimes discordant. Designed by architects Mike Tonkin and Anna Liu, the metal sculpture is part of a Panopticons Arts And Regeneration Project created by the East Lancashire Environmental Arts Network. ELEAN established the project to set up a series of panoptical structures [built to permit the viewing of all parts] across East Lancashire.

“Mid-Pennine Arts held a competition for four sites in Lancashire because they wanted to draw people back into the countryside,” says Tonkin of Tonkin Liu, London. “When we were invited to participate we asked what the sites had in common with each other. Their answer was wind. So we decided to focus on sound as well as the site itself.” Tonkin Liu is an award-winning firm that combines architecture, art and landscape. The company’s designs are tailored to location, people and culture to create projects of significance. 

Making metal sing
For this project building a connection between sound and a sculpture that could entice people to hike through fields and moorland to higher altitudes brought to mind the Brothers Grimm fairy tale the Pied Piper of Hamelin Tonkin recalls. The story follows a stranger who uses a magical pipe to lure away the town’s children. “As architects we feel we also are storytellers,” he says. “We knew we wanted to incorporate the idea of a musical pipe so we decided to create a sculpture made up of steel tubes. We chose to shape the tubes into the profile of a tree because a tree is the only thing that indicates wind direction and provides shelter while allowing you to view the scenery.”

Tonkin and Liu developed a special drill with the capability to drill backwards cutting holes in the underside of the tubes at a specific angle much like a flute. The architects first experimented with plastic tubes by driving area roads and holding them outside the car window until they achieved a sound. “It took us nearly three months before we got the first sound,” says Tonkin. “After cutting holes at different angles we conducted further experiments to identify the right sounds.”

The architects performed a structural analysis to target areas of stress since compressive strength was a critical performance requirement. To meet budget and functional requirements Tonkin and Liu selected mild steel tubing with a center thickness of 8 mil and an end thickness of 3 mil. The tubing was hot-dipped galvanized to give it a 25-year lifespan before being prefabricated as a kit. “Each tube was laid out in a circle with a ring on the top and bottom making it easy to bolt them down,” says Tonkin. “Since the layers of tubes were heavy, they couldn’t be very large.”

Sculpture draws visitors
Crown Point was selected as the site for Tonkin Liu’s sculpture. Ground preparation included removal of an existing electrical box and installation of a concrete foundation. The sculpture was installed in a day and a half and stands 10 ft. high. Visitors can reach the sculpture using a footpath from a nearby car park. Christened the ‘Singing-Ringing’ tree, the sculpture appears to bend against the high spot’s air currents. As the wind blows the tree’s pipes produce unique musical notes that cover several octaves. “The tree was constructed of stacked pipes in varying lengths,” says Tonkin. “Only 25 of the tubes produce sound. The other tubes primarily serve as structural and aesthetic elements.” The pipes are tuned so that they do not disturb the wildlife. The sculpture was built in 2006 and won the national award of the Royal Institute of British Architects for architectural excellence in 2007. The sculpture’s shiny finish has since weathered to a rich patina. “The tree has been visited over and over again,” says Tonkin. “It also has become a popular spot for people who have guests. Overlooking a panoramic view that ranges from Pendle Hill to Worsthorne Moor, Tonkin adds that each time somewhat sits under the tree, it sings a different song.  MM

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