Nestled amidst the vibrant cityscape of Auckland, New Zealand, the Old Mangere Bridge stood as a cherished symbol of community connectivity for over a century. However, time and wear had taken their toll, necessitating the replacement of this beloved landmark. Waka Kotahi NZ Transport Agency embarked on an ambitious project to create a new and improved walking and cycling connection that would honor the bridge’s legacy while establishing a new iconic landmark for the area. Construct n3D completed the steel fabrication shop drawings and coordinated much of the onsite works with the benefit of a live asbuilt 3D model.
Technical Triumphs Amidst Complex Challenges
The project presented a unique set of challenges due to the scale and complexity of the geometry. The arch, with its variable geometry and deck cambering, demanded meticulous planning and execution. The coordination of in-situ concrete piers, precast panels, and balustrades into the steelwork aesthetic required exceptional precision.
The team meticulously planned the lifting of the steelwork over water to avoid interference with nearby transmission lines. Ensuring the precise alignment of all arch segments was crucial, as any discrepancies could compromise the structural integrity of the bridge. Point cloud scanning technology was employed to verify the lengths of the segments, ensuring their ability to form the arch seamlessly.
A Symbol of Resilience and Community Spirit
The project’s total cost amounted to $38 million, utilising 510 tonnes of steelwork, including balustrades, for the 60m-long radial deck. The arch, standing 12m high, boasts a variable trapezoidal profile of 2.2m wide x 0.8m high at the apex. Eighteen individual deck units were fabricated into transportable modules, delivered from Napier to Auckland, and then joined in a site compound. The end deck units incorporated the start of the arch, while the remaining three arch segments were fitted in-situ above the water.
The Old Mangere Bridge Replacement project stands as a testament to the resilience and community spirit that define Auckland. The new bridge not only provides a vital walking and cycling connection but also serves as a beacon of innovation and design excellence.
