An innovative new floating wharf at the Port of Broome could signal a shift in how engineers approach marine infrastructure in extreme tidal environments.
At the Port of Broome, extreme tides create a constantly shifting work environment. With more than 10 m between high and low tide, a wharf that works at one moment can become inefficient or unusable the next.
In 2023, developers noted that these conditions were creating major bottlenecks for Broome’s growing mix of commercial, export and tourism operations.
In response, engineers proposed an alternative approach to the existing fixed infrastructure: a 165 m long floating pontoon wharf, capable of rising and falling with the tide.
Located adjacent to the existing port, the facility – known as the Kimberley Marine Support Base (KMSB) – is designed to support industries ranging from mining and energy to agriculture and tourism.
Floating systems such as this are fairly common in small marinas, but scaling them up to handle large cargo vessels and cruise ships is rarely attempted, said Simon Sutherland MIEAust, Project Director at TAMS Group and leader of the engineering team behind the KMSB.
“Typically in engineering, if you’ve got a project, you can look around and use current engineering designs as a basis. But we didn’t have that luxury with this one,” he said.
“We had to work out how we were going to secure the floating wharf in position so that it could float up and down in these 10 m tides, but also not get swept away with the strong currents and the cyclonic waves that go through the area.”
This required the team to develop a custom solution to secure and stabilise a large floating structure in a highly exposed environment.
Designing for extremes
During the planning stages, some stakeholders – including members of the community and the local Port Authority – expressed concerns about whether the facility could withstand extreme weather events without breaking free and damaging existing infrastructure.
Unlike smaller floating assets that can be relocated ahead of storms, the KMSB wharf is designed to remain in place for a 50-year design life, Sutherland explained. That required a robust structure capable of resisting cyclone-induced waves, currents and winds.
“We had to do a lot of testing to determine what those loads were going to be, and how we’re going to deal with them so that the structure stays in position,” he said.
To validate the design, the team built a 1:40 scale physical model of the wharf and the surrounding environment at the Danish Hydraulic Institute in Copenhagen.
The test environment recreated Broome’s bathymetry (the shape and depth profile of the seabed) to accurately simulate how waves and currents interact with the structure.
“We flooded the wave tank and propagated some waves, and then we measured the loads that were required to hold the barge in position,” Sutherland said.
These results were then calibrated against computer models to refine the final design.
This modelling process helped provide peace of mind by demonstrating that the wharf could withstand a one-in-500-year cyclone event.
Putting 9000 t of steel to work
Broome’s remote location and limited industrial base made large-scale on-site fabrication impractical. Instead, almost all the structural components of the wharf – including approximately 9000 t of steel for the pontoon – were fabricated offshore in China.
The floating pontoon itself was then transported via semi-submersible ship and installed between restraint structures, which were then closed and fixed into position.
To ensure the wharf can accommodate ships up to cruise-liner scale, the berth length is extended to 250 m through the use of “berthing dolphins” – separate floating structures used to moor vessels and extend the usable berth length.
Given the harsh marine environment, protecting the steel structure from corrosion was a key design consideration.
“There’s a cathodic protection system on the barge to slow corrosion down, which is basically a huge number of sacrificial anodes on the underside of the steel hull,” Sutherland said.
“There’s also a corrosion allowance built into the structure – it’s designed so that a typical loss of steel over 50 years is accounted for.”
Bridging fixed and floating
Connecting the floating wharf to land introduced another layer of complexity, since the team needed to ensure safe vehicle access across a constantly changing elevation.
“This particular aspect was probably one of the most challenging parts of the project – designing what we called the ‘linkspan’, which was the bridge between the fixed and the floating,” Sutherland said.
“If you had it too short, the steepness of the ramp at low tide would be too great … But the longer you make it, the more structural steel you need to span that distance. We landed on an 80 m span for the linkspan, which still ended up weighing 900 t.”
The steel structure uses a tubular truss system, with a fixed hinge at the landside end and rolling supports at the seaward end that allow it to move as the pontoon rises and falls.
At low tide, the bridge operates at a gradient of 4.75°, reducing to just 0.8° at high tide.
Unlocking capacity and resilience
The Port of Broome is already seeing the impacts of the KMSB’s flexibility, efficiency and additional berth capacity.
“Previously, ships have been held up for a week or so waiting for a berth to become available at the port,” Sutherland said. “Now, with the additional facilities, it’s unlikely that a ship will ever have to wait.”
The facility also strengthens regional resilience. In extreme weather events, when road access to Broome can be cut off, the port provides an alternative supply route for essential goods.
The KMSB could also provide a model for similar projects in areas where extreme weather conditions make fixed wharves unsustainable. Beyond their resilience, floating wharves can also be faster to build and require less on-site labour, says Sutherland. From mobilisation to operation, the entire KMSB build took around nine months, which he estimates is less than half the time it would take to build a traditional fixed wharf.
“I think people will see that this has been successful, and that will give them confidence to look at floating wharves in the future,” he said.
One of the biggest learnings his team took from the project was to keep pushing forward, even when a solution hasn’t been proven before.
“A lot of people said this project couldn’t be done – that the site was too exposed, and we wouldn’t be able to engineer it,” Sutherland said. “We went through four independent reviews because of nervousness around the concept and the fact that it hadn’t been done before.
“There was a lot of skepticism, and that can get you down at times. But for someone looking to do a cutting-edge or a difficult project, my advice is stay optimistic, and don’t let people talk you out of doing it, because problems can be overcome.”
The project was recently named a finalist in the Australian Construction Achievement Award, recognising the efforts of the engineering team that brought this ambitious concept to life.
“Our team battled a lot of adversity in the design and approvals phase, so to see it successfully constructed and operating for six months now gives our team an enormous sense of pride,” Sutherland said.
Do you know an innovative engineering project worthy of recognition? Nominate it for the 2026 Engineers Australia Project of the Year.
