McConnell Dowell was awarded this D&C contract for the replacement of an historic 90-year old, one-lane bridge with a new two-lane bridge with footpath at Kawarau Falls in Queenstown to improve traffic capacity in the area. The bridge is a curving, 250m-long, 14m-wide structure that is attractive, durable, and low maintenance.
To deliver the new bridge, McConnell Dowell worked with consultants Novare Design, Coffey International, Boffa Miskell, and Hadley Consultants, with support from Arup NZ, Holmes Consulting and MWH. Construction of the bridge structure commenced late 2015 and is expected to be completed April 2018.
- 252m long bridge
- 45m long beam span
- 342t of structural steel
- 758t of reinforcing steel
- 24m launch nose
- 150t crawler crane
- 2000m3 of concrete
- 2.1m dia concrete piles, 7m into the rock
Customer: New Zealand Transport Agency
Location: Queenstown, New Zealand
Contract Type: Design & Construct
The bridge is being constructed adjacent to, in, and over the Kawarau River, with a topography of steep banks running down each side of the river, requiring innovative temporary works, including a temporary steel trestle, and stringent environmental controls to ensure there is no runoff into the pristinely clear Kawarau River. The bridge is also technically complex due to its geometry – it is two thirds curved and spiral and straight in sections.
The superstructure includes steel girders that form the backbone of the bridge. Using a launch ‘nose’ attached in front of the girders to construct a bridge is fairly uncommon in New Zealand and has only been done a few times before. It is the 24.5m long engineering keystone to the Kawarau Falls Bridge, and was designed in-house by McConnell Dowell. The launch nose allowed short sections of the bridge (between 16 and 22 m long) to be constructed onshore in the small space available. These sections were then launched out to the piers using hydraulic rams. The ‘nose’ minimises the temporary works required and maintains river access both up and downstream, minimising disruption to river users, including tourism operators, and preserving the sensitive river environment.
We are working closely with both the Otago Regional Council (ORC) and Queenstown Lakes District Council (QLDC) to ensure compliance with project consents. A proactive stakeholder communications plan has been implemented to keep stakeholders, including the local community and tourists informed of developments, which is particularly important during peak holiday seasons. A traffic web camera on the north side of the existing single lane bridge enables motorists to make better informed decisions about their travel plans, as well as real time updates on estimated travel times.
The project team incorporated a substantial variation to the project to include the design, supply, and installation of bulk water and wastewater mains to minimise the overall costs and future disruption to the Transport Agency.
The Kawarau Falls Bridge is scheduled for completion in April 2018.