OPENING: 29 JANUARY 2016
ARCHITECTURE: ARUP ASSOCIATES
ENGINEERING: ARUP PERTH
The Elizabeth Quay Pedestrian Bridge has been an amazing opportunity for our architectural team in Arup to work with the best of Arup Engineering skills. Our concept for the form of the bridge was driven by a desire to have a simple and iconic form that respected the existing master plan for the Quay and ensured that full advantage was taken of the prominent location of the bridge within the city. We had to achieve a considerable change in level from the Williams Quay to the western end of the bridge to clear the navigation channel required for ferries.
The curved form of the bridge deck was the solution that allowed us to create the extended ramps required to clear the navigation channel and achieve entry points to the bridge that were critical for legible access and integration with the master plan. Having achieved these geometric challenges, we now had to engineer a solution. Our target was to compliment the S form of the bridge deck with arch forms that would reinforce the experience of movement through the structure and across the bridge.
The bridge deck is constantly changing in height and always curving in plan – the arches needed to enhance this experience. We worked closely from the outset with engineers using analysis software to show how efficiencies could be made in arch geometry relative to the bridge deck geometry. We wanted the drama of the leaning arches, we also wanted the arches to optimized in their cross sectional form to the structural work they are doing. We also worked closely with our wind engineers to ensure that vibration and vortex shedding issues were overcome. We wanted transparency to the balustrades, yet some level of solidity was initially required to overcome wind impacts which could generate vibrations within the bridge structure.
Another area of design which defined the form of the arches was the lighting concept. We wanted the illumination of the arches to be visible from both sides – from the city and from across the river. To achieve this we generated a 5 sided cross section, so that at the apex of the arch two faces are visible in elevation and can be illuminated from a single line of uplighters to the edge of the deck. The result is everything we sort to achieve in terms of simple and pure structural forms, complimented by a rationalised modular architecture to the fascia finishes, balustrading and timber decking. This was only possible through the use of shared modelling, with both architects and engineers using Rhino + Grasshopper scripts to control the geometry definition – scripts that were shared on a daily basis to ensure that structural analysis kept pace with architectural geometry
KEY ARCHITECTURAL DESIGN TEAM: