The Onepoto pedestrian footbridge design reflects the radical concept of integrating architecture onto structure embedded into an urban fabric. In response to the Government Urban Design Protocol, North Shore City Council wanted to provide a functional structure for pedestrians to cross safely, but at the same time offer a unique experience for users by incorporating architectural elements into the bridge to create interest, and to blend it into the surrounding landscape.
Adjacent to Onewa Road on Auckland’s North Shore, the bridge crosses a tidal stream and mangroves. The exact site was determined by motorway traffic, and the need to respect the placement of existing native plants and trees. Historically, the site was an indigenous fishing area; therefore the fishbone metaphor is also reflected in the design.
The form of the bridge was processed completely digitally. The use of modelling software enabled and encouraged three-dimensional non-uniform design. The complex organic form was derived through a succession of manipulations, beginning as a cylinder but, by controlling the tension of the surface through a multiplicity of nodes, a shape that accorded with the site’s intent was achieved. Construction materials were then introduced to the model to take the concept from the virtual into reality.
Unique glue laminated rib components were geometrically crafted to varying lengths; once grouped in a specific order they emerge into an undulating sinuous form. The ribs become more than purely aesthetic additions, rather serving as a shield from the busy traffic on Onewa Road, giving real as well as perceived safety to pedestrians, and providing a sheltered outlook onto the mangroves and the Onepoto domain. With the aspect of visual pollution an important driver, the ribs conceal the concrete beam of the underlying structure and allow for the bridge to be completely camouflaged within the natural mangrove environment.
Engineering constraints allowed for a maximum of 100mm cut-outs in the glue laminated members to create windows, which offer occasional glimpses of the Auckland skyline. The response to this constraint was through a subtle skewed cut-out from a single member. This created a sinuous visual flow as the pedestrian progresses along the bridge. The window design placement is subtle. The central window was designed to be significantly larger than the others to enable viewers to regard the abutments of the old historic bridge.
The intention of the project was not only to create one special element, but rather to create an experience and a journey for the pedestrian on this path. The element of surprise is repeated throughout the walk up the hill, as once the pedestrian embarks onto the abutment they are surrounded by high vegetation on either side of the walkway.
Passion for articulated crafted design and a drive for realistic visual communication helped all involved in the project believe and appreciate what was trying to be achieved. The result is a unique structures that serves its functional purpose, but also reflects the historical aspect of the site, provides interest and a pleasant experience to users, and integrates seamlessly with the surrounding environment.