Waka Kotahi NZ Transport Agency will start work tonight on a complex and temporary repair to the damaged strut on the Auckland Harbour Bridge which has closed four lanes on the centre span.
The temporary repair is to allow two lanes on the centre span to be opened while work continues on a permanent solution.
The southbound clip on lanes will be closed overnight tonight, Tuesday 22 September from 9:00pm to 5:00am. The closure includes:
Motorists are advised to use the Western Ring Route (SH20/SH16/SH18) while the southbound lanes are closed.
If the repair cannot be completed tonight, the clip on lanes will be closed again on Wednesday night.
The repair involves removing the lower half of the 22.7 metre truss and replacing it with a freshly fabricated section of steel. The load-bearing truss weighing about four tonnes was damaged on Friday when a truck crashed into it after being hit by 127kph wind gusts.
“This is a complex undertaking and has never been done before so the bridge team must do extensive testing on the bridge before opening it up to live traffic. This includes mathematical peer review by independent experts which we are doing in parallel to the construction of the temporary piece,” says Waka Kotahi General Manager Transport Services, Brett Gliddon.
“Once the temporary fix is in place there will be real life testing with heavy vehicles to ensure it performs to the design specifications and requirements. Only then will a final decision be made about whether the temporary fix is suitable to allow the re-opening of additional lanes.”
“Once that decision has been made, it is expected that two lanes on the centre-span of the bridge could open to traffic.”
Work is also continuing at pace on a permanent repair of the damaged truss in order to re-open all lanes on the Harbour Bridge. However, this work will take time and is weeks away from installation.
“The teams are working to design and peer review the replacement parts for both the temporary and permanent solution, source the materials, manufacture the part and plan for installing it,” says Brett Gliddon.
“The bulk of this time is in the design, calculation and 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.
“The new modelling is necessary because the materials of the new structure will not exactly match those that were installed 61 years ago.”
While the damaged component of the structure is important, there is no risk to the structural integrity or overall safety of the Harbour Bridge. The north and southbound clip-on lanes are safe to use as they have their own supporting structure.
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