For over 80 years the Fremantle Traffic Bridge has connected people over the Swan River from Fremantle into Perth’s western suburbs. The bridge has been deteriorating over several years and needs to be replaced. Main Roads Western Australia require a new bridge that would provide safe active transport infrastructure, serve as an iconic gateway to the Port city and be delivered on a fast-tracked timeline to keep people and transport moving.

As part of the Fremantle Bridges Alliance, we leveraged our global bridge engineering expertise, alongside local experience, to design the new Fremantle Traffic Bridge – Australia’s first extradosed bridge. This innovative design combines balanced cantilever precast segmental construction with cable supports. We also engineered the bridge to accommodate an unconventional construction approach, allowing it to be built alongside the existing bridge, minimising closure time.

The new bridge will provide safe and active connections from Fremantle to Perth’s western suburbs for at least the next 100 years. River users will benefit from improved navigational safety with higher and wider clearances for boats and other watercraft. Cyclists and the community will have wider pathways on each side of the bridge. This project has the potential to become a central feature in Fremantle’s future development.

Building an iconic bridge with minimal disruption

An extradosed bridge, combining prestressed box girders and cable support, has never been built in Australia. This design was chosen with the community in mind, offering Fremantle an iconic gateway into Perth. With fewer piers for river users to navigate, minimal impact on Beach Street and Canning Highway, and a construction method that minimises the length the existing bridge requires to be closed, the design balances functionality with local needs.

Our team, working as part of the Fremantle Bridges Alliance, faced the challenge of delivering this iconic bridge design within an Australian context. To minimise risk, we mobilised our experts in extradosed and precast segmental bridge design from Europe to collaborate with our local team on the concept and detailed design. With our global experts embedded in our team, we have the expertise to realise this unconventional design approach and upskill the local industry.

The design approach allows for most of the new bridge to be constructed alongside the existing bridge, which will minimise extended disruptions and closures. The precast segmental design means the bridge is designed to be built in short sections which are precast offsite, which allows for greater quality control and safer construction works. The methodology allows for a significant portion of the bridge to be built before the existing bridge’s closure, reducing the overall shutdown period. Our approach reduces the expected bridge closure time by approximately 50 per cent. 

Designing safe and accessible active transport links

The bridge provides an opportunity to create safer and more accessible transport connections for the community, cyclists and river users. More than just a traffic bridge, the Swan River Crossings project integrates seamlessly with the urban landscape, enhancing Fremantle’s sense of place.

On the bridge, the pathway for pedestrians and cyclists has been expanded significantly, so people walking, cycling, and using wheelchairs can comfortably share the space and pause to take in the river views. Beneath the bridge, the number of piers has been reduced from 24 to two, providing wider clearances and making it easier and safer to navigate journeys below. The new bridge will also have a two-metre increase in clearance, to allow for safe movements of existing and future watercraft.

As Fremantle continues to grow, with new economic and land use opportunities on the horizon, the new Fremantle Traffic Bridge will serve as a vital link and landmark connecting freight, people and places.

WSP / Laing O’Rourke