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Source: New Zealand Transport Agency

Waka Kotahi NZ Transport Agency says the design and fabrication of the permanent strut for the Auckland Harbour Bridge is now well advanced.

The Grade 350 L15 steel for the strut has been sourced and manufactured by NZ Steel and delivered to fabricators in Whangarei. It will be transported to Auckland by truck.

The strut will replace the one damaged when 127 kph winds blew a truck into the bridge superstructure last Friday. The temporary repair has not restored the strut’s load-bearing function, but when the new strut is installed it will return the bridge to its full load capacity. Two of the bridge’s eight lanes will remain closed until it’s installed.

“Teams are working at pace to design and peer review the replacement part for the permanent solution and to manufacture and plan for installing it,” says Waka Kotahi General Manager Transport Services Brett Gliddon.

“Fabricating the 22.7 metre strut and getting it into position is the quicker part of the process. It will take several weeks before it is tensioned up as a load-bearing part of the bridge superstructure.”

The bulk of this time is in the design, calculation and external peer review of the new strut in relation to how it will impact on the performance of the whole bridge. This includes careful calculations on how to re-balance its load-bearing function.”

Installation of the new strut will require closure of the southbound lanes of the bridge and this installation will take longer than the temporary fix.

“On Tuesday night the team only had to remove the damaged part of the strut, install the temporary section and bolt it to the bridge deck. This time, they’ll have to remove the temporary section and the old section connected to the top of the bridge and then install the new permanent strut. That will take much longer.”

A date for the installation is still not known.

As well as the safety and performance of the strut, Waka Kotahi is also paying careful attention to how the new piece will look on the bridge, which is an iconic piece of Auckland’s infrastructure.

The materials of the new strut will not exactly match those that were installed 61 years ago. For example, it will have welds where the old strut had rivets.

Waka Kotahi is working with a consultant conservation architect to ensure the new strut fits appropriately with the landmark status and heritage values of the bridge.

“The aim is that once it’s installed and had a coat of paint, it will blend in with the rest of the bridge superstructure and the subtle differences will go unnoticed,” says Brett Gliddon.

The steel sheets in a Whangarei workshop that will be fabricated into a new strut for the Auckland Harbour Bridge

The steel being used in the permanent fix of the Auckland Harbour Bridge was manufactured right here in New Zealand. It’s being fabricated here too by Culham Engineering in Whangarei. Managing Director, Rob Kirwan, shows us the materials and explains what the process will entail.

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