Auckland Harbor Bridge – Engineers working on a permanent solution from detailed scans

Engineers working on permanent repairs to Auckland’s damaged Harbor Bridge are working on detailed scans, thanks to the world’s fastest laser scanner.

The New Zealand Transport Agency (NZTA) said in a post that Envivo Ltd collected millions of data points and created a 3D mesh of the area and its damage.

A bizarre incident on September 18 blew a truck into a steel loading beam, rendering the middle lanes useless.

The effects of the closure spread across Auckland’s already congested motorways and continue to cause long delays and traffic jams.

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* Auckland Harbor Bridge: Permanent repair expected in four to five weeks, says NZTA
* Harbor Bridge Damage – Closing of the city’s entrance ramp adds to widespread delays at night
* Harbor Bridge Closure – Work on a temporary fix to reopen lanes to start Tuesday

Two lanes on the bridge reopened Wednesday morning after a temporary fix was installed overnight, but a permanent fix won’t be complete for four to five weeks.

Earlier, NZTA Transportation Services General Manager Brett Gliddon said about nine structural engineers were working on the problem, which required replacing the entire damaged beam from top to bottom.

Gliddon said the work could be done entirely with the materials and expertise already available in New Zealand, and there is no need to bring in foreign experts.

But it is not as simple as finding a new beam and screwing it in.

One has to be built from scratch, taking care that its material and design work with the six-decade bridge, Gliddon said.

Placing the beam will mean using jacks on each side to tension it and push the load onto the bracket, before tightening the bolts.

How exactly did this happen?

At around 11 a.m. on Sept. 18, sudden, strong gusts toppled two trucks as they crossed the bridge, Gliddon said.

One was on top of the bridge when it was knocked over by a gust and crashed into a steel beam, twisting the metal and cutting it where it connected to the bridge below the road surface.

Gliddon said the wind was 60km / h before it shot out to a 127km / h gust before subsiding again.

“We were hit by an absolutely monstrous gust of wind that caught a truck that was right at the top of the bridge.

“That is really difficult to design.”

The beam did what it was supposed to do, cutting the bolts, rather than pulling and damaging other support members, with its load transferred to other supports in the steel truss.

The bridge is still able to stand on its own, but engineers are unwilling to allow traffic on the original inner lanes, which opened in 1959.

The two outer rails on each side, trimmed 10 years after opening, have their own support structure and are not dependent on damaged armor.