The destruction was the result of a 1-in-100-year weather event. In January 2023, ex-tropical cyclone Ellie caused record-breaking rainfall, exceeding the amount that fell over the last 20 years combined. Floodwaters peaked at over 15 metres and overtopped the Fitzroy River Bridge, leaving the community of Fitzroy Crossing only accessible by helicopter. The bridge formed part of the Great Northern Highway, a crucial overland link between the West Kimberley and the Northern Territory. It also provided a critical social and commercial connection for locals on either side of the river. 

Enter the Fitzroy Bridge Alliance, composed of four parties: BG&E, an​ international civil and structural engineering consultancy; Main Roads Western Australia; BMD Constructions; and Georgiou Group. Working tirelessly together, they accelerated the urgent project by building strong connections with local operators, suppliers and workers and leveraging their collective knowledge and innovation. 

The team charged with rebuilding the bridge had two major priorities. Firstly, rebuild the bridge as quickly as possible. The collapse was causing major freight disruption and had cut essential access to local communities, so a swift resolution to the situation was imperative.  

Secondly, ensure the new bridge was resilient enough to withstand heavy traffic, adverse weather and flood events of this magnitude for the foreseeable future and beyond. 

“It was a team effort from the beginning. BG&E was engaged by Main Roads Western Australia at the end of January 2023 as lead designers to develop a preliminary concept for the Fitzroy River Bridge disaster recovery project in the Kimberley,” explains Engineers Australia member Emir Muhlisic CPEng MIEAust, Associate Director at BG&E. 

The biggest issue facing the engineering and construction teams was time. In just under a year more flooding could be on the way, a deadline that couldn’t be moved. 
“When we examined the length of the river, the times of the year the river floods, and how long we’d need to construct, it was apparent that we needed to launch the bridge. This would remove the risk that the water level would come up before the bridge had been completed and stop work onsite because the superstructure could not be constructed over the flooded river,” recalls Engineers Australia member Marcus Toleman, CPEng MIEAust and Associate at BG&E.  

Of course, structural engineers are built for these kinds of challenges. By June 2023, five months after the initial collapse, the old bridge was removed, and construction began. A three-bay launch area was arranged on the western embankment to minimise construction from the actual riverbed. Most bridges in the region are constructed from concrete, but because of time pressures the teams worked fast to design a steel-concrete composite bridge. The use of REDCOR® weathering steel was incorporated as it requires less maintenance than galvanised or painted steel, an important consideration for a major bridge in such a remote location.  

The bridge superstructure was assembled on the bank of the river and launched incrementally across a line of piled foundations secured into the riverbed. Construction occurred both onsite and offsite, increasing the speed of the project. The engineering team at BG&E also managed the protection and relocation of utility services, while conducting flood modelling and hydrology assessments. 

The urgency and necessity of the project even built bridges within the local community. 25% of the entire construction hours were worked by Indigenous Australians. This created an employment boost for residents in a town with some of the highest unemployment in WA. While infrastructure was being restored, local community members were developing skills towards further employment opportunities and future economic resilience. The Fitzroy Bridge Alliance also welcomed 55 students and teachers to view the construction in action from the Wangkatjunga Remote Community School as part of their Schools Program. 

Project leaders prioritised using local materials and providers, further contributing to the local economy and helping to repair some of the financial fallout triggered by the original bridge collapse. BG&E factored in resource efficiency and sustainable outcomes. This meant tracking material inputs and outputs, testing local aggregates and reusing surplus materials to support future regional projects. A significant amount of material was repurposed to reduce waste. 

The original plan was to have the bridge partially complete before the onset of 2024’s wet season, with the remainder to be completed when river waters had receded. Members of the community and the wider region were thrilled when the bridge was completed in just 288 days, a whole 6 months ahead of schedule.

The new Fitzroy River Bridge is now the longest weathering steel road bridge in Australia. The six-beam superstructure is 270 metres long – nearly 100 metres longer than its predecessor – and is twice as wide, with two lanes for vehicles. It has an integrated pedestrian crossing, blade wall piers and 1200 metres of piles installed to enhance resilience against future extreme flooding. Taller, longer, wider and stronger than before, the Fitzroy River Bridge stands ready to keep the state and local communities connected in the face of future weather events.