Location: Westonbirt, Gloucestershire
Client: Westonbirt Arboretum
Sector: Unique Experiences
Royal Academy Summer Exhibition Prize Winner, 2010
The Westonbirt Tower is a pioneering experience that will bring users into the tree canopy and improve the all year round attraction to the Park. The proposed tower is 30m high and with its lightweight structural frame of green oak and large open plan circular platform spaces, the tower would be a unique structure rising delicately through the spectacular Westonbirt Arboretum.
Visitors arriving at the base of the tower can ascend via the dedicated up staircase that spirals up through the timber lattice past three intermediate platforms. They can then descend by the dedicated down stair.
The lower platform offers the chance for children and adults to break out into an elevated play zone that will include a netted walkway, suspended 10m above the ground level.
Visitors can continue up to the second platform – the learning zone – where groups of school children will be almost within touching distance of the tree canopy and can benefit from the educational interpretation provided. Visitors will then be able to safely admire the outstanding 360-degree views from the top platform.A low energy lift will be installed and will run up and down inside the core servicing each platform level.
The viewing platforms are finished with a translucent steel mesh that spans across a grillage of galvanised rectangular hollow sections. These transfer load to a central steel core and outer ring truss. The ring truss is supported by a timber hyperboloid that passes load through its doubly ruled surface via a lattice of straight struts working efficiently in compression. The struts are pin jointed at every interface providing a shear transfer between the crossing members, but releasing the build up of bending effects.
The core contributes to the lateral stability of the frame whilst transferring compressive loads from each platform to the ground level. The core and lattice are supported by a flexible array of screw piles, connected to a steel ground frame.