What it has principally in its favor is a wonderfullandscape setting, to which the bridge provesresponsive in a number of ways. For one thing, itcurves in plan, gently resolving the divergentgeometries of the north and south banks. In orderto keep it above flood level, it extends far beyondthe river’s edge on both sides. Massiveembankments serve to anchor — both structurallyand visually — either end in the ground.
The structure is not, however, a single span. A third point of support is provided by a small island two thirds of the way alongthe bridge’s length. The island’s eccentric location invests the structure with an asymmetry that Hadid — if not her engineer— has clearly relished.
Zaragoza Expo 2008 is dedicated to water and sustainable development.The basic module from which the whole structure has been derived is a triangular steel frame. It is repeated at 3.6mintervals along the bridge’s length, and adjusted in height and width with each iteration. What emerges through thisprocedure is an arched truss which is then lined out to become a spatial enclosure.
The pods are stacked according to precise criteria – aimed atreducing the section of the bridge as much as possible where thespan is longer (approximately 185m from the island in the middleof the river to the right bank), and enlarging it where the span isshorter (85m from the island to the Expo riverbank). One longpod spans from the right riverbank to the island, where the otherthree are grafted into it, spanning from island to left bank.
ZARAGOZA BRIDGE PAVILION [ZARAGOZA, SPAIN] Underneath the floor plate, a resulting triangular pocketThe Zaragoza Bridge Pavilion is organized around 4 main objects, or space can be used to run utilities. Floors inside each“pods” that perform both as structural elements and as spatial pod are located at the Expo principal levels: +201.5menclosures. The Bridge Pavilion design stems from the detailed (the soffit of the bridge is at +200m, flood protectionexamination and research into the potential of a diamond shaped minimum level of the Ebro River at the location of thesection – which offers both structural and programming properties. As Bridge Pavilion) +203m, +206m and +207.5m for thein the case of space-frame structures, a diamond section represents a upper level.rational way if distributing forces along a surface.
The diamond section has also been extruded along a slightly By intersecting the trusses/pods, they bracecurved path. The extrusion of this rhombus section along each other and loads are distributed acrossdifferent paths has generated the four separate ‘pods’ of the the four trusses instead of a singular mainBridge Pavilion. The stacking and interlocking of these truss element, resulting in a reduction in size ofelements (the ‘pods’), satisfies two specific criteria: optimizing load-bearing members.the structural system, and allowing for a natural differentiation ofthe interiors, where each pod corresponds to a specific exhibitionspace.
Spatial concern is one of the main drivers of this project. Each zone within the building has its own spatial identity; their nature varies from complete interior spaces focused on the exhibition, to open spaces with strong visual connections to the Ebro river and the Expo. Natural surfaces have been investigated when designing the Pavilion’s exterior surfaces. Shark scales are fascinating paradigms both for their visual appearance and for their performance. Their pattern can easily wrap around complex curvatures with a simple system of rectilinear ridges. For the Bridge Pavilion, this proves to be functional, visually appealing and economically convenient. The building’s envelope plays an essential role in defining its relation to the surrounding environment and atmospheric variations. The project has been designed to allow its interior to be thoroughly enlivened by the effect of atmospheric agents, such as the Tramontana wind blowing along the Ebro and, the strength of Zaragoza’s sunshine. During the Expo, a single weathering layer will enclose the building to protect it from rain. This Shark scale skin will be generated by a complex pattern of simple overlapping shingles. Some shingles can rotate around a pivot, allowing forThis interlocking of the pods has given the design many exciting temporary opening or closing of part of the façade. The pattern ofpossibilities. Interiors become complex spaces, where visitors move shingles overlapping each other gives the Bridge Pavilion thefrom pod to pod though small in-between spaces that act as filters – or widest variety of natural light via several degrees of aperture sizes:buffer zones. These zones diffuse the sound and visual experience from rays piercing through tiny apertures – to wide, full sizefrom one exhibition space to the next, allowing for a clearer openings. Large apertures are located on the lower level, inunderstanding of the installation content within each pod. The identity correspondence with either end of the bridge, allowing for theof each pod remains thoroughly readable inside the pavilion, almost greatest degree of visual contact with the river and the Expo.performing as a three-dimensional orientation device.
•The bridge comprises four such trusses. Two are laid end to end, forming the public route. The other twoare rammed in from either side and serve as exhibition halls. The plan that results is trident-like, the handlebearing on the south bank, the forks pointing north.•Early on in the project’s development, the design team considered the possibility of an engineering solutionbased on a series of shell structures. This was ultimately rejected because the architect felt that such amonolithic structure would give the project the presence of a piece of heavy engineering. What Hadidwanted was a finer, more building-like scale. The bridge’s external image is very largely, therefore, a matterof cladding.•The lower level has been faced in premoulded steel panels, giving it a sinuous, aerofoil profile. Above, weare presented with a skin of mosaic-like glass-reinforced concrete panels. Comprising a series of interlockingtriangles, this treatment is built up of ten different cutting patterns, each of which is assigned a distinct tone,graduating from black to white.