The 22m-high Elizabeth Quay pedestrian and cyclist bridge is a suspension bridge along the Swan River in Perth, Australia, and part of the river’s ‘bridges’ recreational route.

Arup was the design lead consultant for the project, tasked with designing a bridge that had iconic architectural appeal for those using or viewing the bridge, as well as functionality both for those crossing it and vessels passing below. 

Our design for the bridge was intended to be both dramatic and useful. This included a curved form for the bridge deck, so that extended ramps created enough clearance for vessels to pass underneath and offering pedestrians and cyclists a 360-degree view of the Swan River.

We designed a balance between the dramatic impact of the bridge’s leaning arches with their structural function, and designed those arches sweeping descent towards the water to rest on concrete piers supported on piles socketed into the rock bed. 

Vessels needed enough space to travel under one section of the bridge, while pedestrians needed smooth access across to the island at the end of the bridge. Arup’s architectural solution was a curved form for the bridge deck allowing the creation of extended ramps to clear the navigation channel.

The Elizabeth Quay bridge is part of a sequence of bridges bringing residents into closer active-travel contact with the river, a defining geographic feature of the city of Perth. Our digital design work allowed the bridge to be iterated and analysed as we went through design with the architects, meaning that this complex vision for the bridge could be realised in multiple versions alongside adjustments for calculations such as wind vibration. 

Artfully structuring complex curves

The digital design workflow was a highly collaborative process that proved to be pivotal in the successful delivery of the project. The architect used Rhino and Grasshopper as parametric tools to converge quickly on the architecturally-desired, ‘S’-shaped bridge concept. Preferred sculptural forms of the bridge were developed parametrically with the architect using Grasshopper, opening up the opportunity for Arup’s engineers to link into the architect’s parametric scripts to integrate the design workflow.

Working from the same shared Grasshopper canvas, the engineering team were able to generate analysis models to assess the structural performance of bridge form as it developed in concept. 1D finite element models were parametrically generated directly from Grasshopper to GSA using Arup’s very own Salamander plug-in. These direct digital links provided the design team with the ability to optimise and rationalise the complex bridge form in a very short time-frame.

As an outcome of the digital workflow, complete coordination and alignment of design between architect and engineer was maintained throughout.

Public Transport Authority City of Perth / Arup Associates (London) / DASSH / Electrolight / JMG Building Surveyors