Envision a sweeping curve of steel and concrete. That is the Kawarau Falls Bridge. Opened recently, the two-lane Kawarau Falls Bridge carries State Highway 6 south. It replaced the old single-lane bridge that ran across the top of the Kawarau Falls Dam.
Let’s delve into the story of this structure. The new Kawarau Falls Bridge eliminates delays. It improves the State Highway link from Queenstown to Southland and Milford Sound. It is a welcome addition to the scenic Queenstown landscape.
The old single-lane bridge has its own tale. It was constructed in 1926. Originally, the one-laner was built as a dam. Its purpose was to allow gold prospecting on the Kawarau River bed. The dam was built in 1920 at a cost of £106000. That equals about $10 million today. The hope was to hold the waters of the Wakatipu back. This would expose unworked gold reefs downstream. Unfortunately, water levels did not fall far enough. Returns on this scheme were modest.
The new Kawarau Falls Bridge project had challenges. The design was technically and logistically challenging to execute. Its geometry is two-thirds curved. Its location over the pristine Kawarau River has steep banks running down each side. This presented significant construction challenges. The space was incredibly confined. All work needed careful planning and coordination. Works were undertaken over and beside a historic mill stone wall. The wall needed protection.
McConnell Dowell delivered the Kawarau Falls Bridge for the NZ Transport Agency. The bridge is 250 meters long. It is a curved structure of steel girders. These form the backbone of the bridge. The weathering steel girders blend with the environment. They were installed using a unique launch nose method. McConnell Dowell temporary works engineers designed it in-house.
Using a launch nose method to construct a bridge is uncommon in New Zealand. The 24.5-meter-long launch nose allowed short sections of the bridge to be constructed onshore. These sections were between 16 and 22 meters long. They were launched to pier columns driven into river rock. Hydraulic rams from a temporary trestle were used. The nose minimized temporary works. It maintained river access. This minimized disruption to river users. It preserved the sensitive river environment.
Community involvement was actively encouraged. Locals even helped to launch three sections of the bridge deck. Around 3000 people walked across the new Kawarau Falls Bridge at its opening ceremony. The opening of the new 252-metre bridge was spectacular. After a blessing and speeches, dignitaries drove across the bridge in an electric car. They were followed by Queenstown Lakes District Mayor Jim Boult in a Model T Ford. It had rolled off the production line the same year the old bridge opened.
The historic bridge is maintained for cyclists and pedestrians only. It allows long lingering looks into the crystal-clear azure waters flowing below. So, as you cross the Kawarau Falls Bridge, remember its history. Think about the gold rush dreams and the engineering feats that shaped this landscape. It is more than just a bridge. It is a testament to ambition and innovation.