'Edge architecture' is the term Zone architect Imagination chooses to describe the explosion of sharp edges, bewildering angles and floating planes that make up the Journey Zone. But underneath all the visual excitement is a complex structural steel core made of four principal structures shoe- horned into tight spaces around and between other parts of the Dome.
A Small Box and a Black Box stand either side of one of the Dome's access roads connected by a mezzanine floor squeezed beneath the Dome's circuiting, elevated promenade. Standing away from the boxes is a three storey Icon Tower.
Work began first on the 15m square Small Box, supported 5m above ground on three primary trusses propped by tubular columns. Its steel frame and four braced walls deliver a trapezoidal elevation standing 17m tall.
A concrete upstand wall supports much of the Black Box, which is built around one of the Dome's equipment stores. The Black Box quickly compensates for being constrained at the ground by mushrooming outward as it rises upward, its five trapezoidal walls and roof towering over the adjacent Dome mast support.
Walls and roof are clad in aluminium backed by steel frames to provide shear-stiff, suspended planes. The walls support a 150mm thick concrete slab on permanent metal decking forming a promenade deck within the box.
A 450m2 composite mezzanine floor was built partially beneath the Dome's elevated walkway, between the two boxes. The mezzanine cantilevers out from beneath the walkway to be supported by a cluster of tubular V-frames. Structural engineer Buro Happold associate Geoff Werran explains that the V-frames were preferred over vertical columns because they enable loads to be channelled effectively into the underlying piles and away from another of the Dome's mast bases.
The final element of phase one, the three storey Icon Tower, provides vertical circulation. An unbraced, exposed steelwork structure supported by six columns set inboard from the curved perimeter beams, its composite upper floors are supported by a combination of rectangular hollow section beams and I-section/ circular hollow section trusses.
At ground level, adjacent to the Small Box, a large, enveloping entrance space was built. Rising 5m from the back of this space through the Small Box is a 70m long trapezoidal truss ramp. Werran describes designing much of the Zone, and in particular the multi-section ramp, as 'geometrical knitting.
'You have to be able to climb 5m in height within a limited floor plan while displaying a lot of exhibits. To make it fit at all requires a very tight model.'
One of the most dramatic features of the Journey Zone is its aluminium honeycomb clad fins, with their ever varying orientation and profiles. They have a combined length of over 200m and weigh 90t. The two largest are structured by 2.5m deep walk-through trusses, allowing for maintenance of 2,500 constantly oscillating and strobing lights within the fins.
Two smaller fins have a spine of circular hollow section steel joined together by splice plates. All four fins appear to be unravelling from the black box and are held aloft by two 25m high masts.
Werran comments: 'Because very fast procurement was needed we had to allocate manufacture and installation of different elements to a fairly large number of contractors. There wasn't any time to put anything right if there was a clash between elements, so Buro Happold and Imagination developed a multi layered digital model of the entire Zone. This proved invaluable.
'In all, 88 different contractors and consultancies were involved in creating the Journey Zone, which was completed in just 13 months.'
Architect, project manager, project manager and exhibition designer: Imagination
Structural engineer: Buro Happold
Manufacture and erection of mezzanine floor and black box: WS Britland
Manufacture and erection of small box, icon tower and main staircase: Sheetfabs
Manufacture of fins, bridges, ramp and fire wall: KP Martin
Erection of fins, bridges, ramps and fire wall: Surrey Steel