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This London Bridge doesn’t fall down—it does a backbend
By Peter Reina

Thomas Heatherwick on his Rolling Bridge. Photography: Courtesy Littlehampton Welding

Heatherwick collaborated with an engineering team that included structural designer SKM Anthony Hunts of Cirencester. Heatherwick and the firm had been looking for a site to build an all-glass bridge they had conceived in the 1990s, says Alan Jones, a principal of Hunts. Paddington looked like a possible setting when Chelsfield called, but the scheme was ultimately replaced by the Rolling Bridge.

The 4.5-ton bridge is made of eight segments joined together by hinges. Its articulated balustrades act as trusses, with the deck-floor elements acting in tension and the handrails in compression. Seven vertical pistons above the deck hinges form part of the balustrades. They also control the bridge’s opening motion, which is powered by underground hydraulic equipment.

When the bridge needs to be opened, the pistons along the deck elongate. As this happens, articulated sections of the balustrade over each part of the footpath turn toward each other, causing the bridge to curl up. When fully open, the bridge forms a loop with the tip resting on the base. Closing the bridge involves reversing the process in an operation lasting less than three minutes.

Initially the bridge was designed to be retracted into three quarters of a full circle by pulling cables in the handrails. The structure would have opened again under its own weight, without the aid of machinery. But for better access and other reasons, the design team opted for a bridge that would bend into a complete circle, which eliminated the possibility of using gravity’s forces for reopening it. At that stage, the bridge was to be curled section by section, with pistons activated in turn, expending minimum energy, says Jones. Then Heatherwick asked the engineers if the segments could be retracted at the same time and speed. “I think this is a work of art,” Jones declares. “It ceased to be purely structural when its function was determined more by aesthetics than mechanics.”

Considered a maverick among the U.K.’s design circles, Heather-wick has shown a flair for the dramatic at many scales. In 1997, he designed a window display for Harvey Nichols in London that broke the plane between private and public space, extending from the store onto the sidewalk. Upcoming work includes the U.K.’s tallest monument, which will be built at Manchester Stadium; a Buddhist temple in Japan; and a tote bag for clothing manufacturer Longchamp.

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