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Cold Front Today


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So Auckland had a cold front today. Was kind of nice, blew through fairly fast. Bit of rain. Bit of wind. Easily third reef kind of weather.

Now the Harbour Bridge is fucked, and could possibly be out for weeks. Just the middle four lanes mind, so technically a 50% reduction in capacity, but more than that (60%) when you consider the tidal flow.

A truck with a shipping container got blown into a girder, righted itself and kept on going. Girder got sheared... NZTA sorry Waka WhakerUpper just trying to work out how to fix it.

Note that is different to the curtain-sider that got blown over. Predict wind for the bridge showed a sustained just of 70 knts for a couple of minutes. I suspect the peak wind in that was a bit more.

So much for the economy, freight companies, couriers, and tradies trying to get around, or anyone doing business full stop really. At least I have a good reason to work from home a bit longer...

https://www.rnz.co.nz/news/national/426379/auckland-harbour-bridge-lanes-could-be-closed-for-several-weeks

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I am fascinated by the power of the weather, especially a moderately straight forward cold front, to blow a couple of trucks over and take out a piece of key transport infrastructure. That's why I put it in marine talk. The council or govt have nothing to do with the weather, nor with the Harbour Bridge. That would be the New Zealand Transport Authority.

So please don't make it about something it isn't, and please don't go round trolling for a fight. I'm not interested.

The fact that these trucks rolled very close to where that micro burst nailed Westhaven, laid flat a super yacht, sunk some boats and made a cat flip and jump the pier is interesting. I'm starting to wonder if there is something unique about the geography there that creates down bursts. Wind accelerating off the land, or channeling between the land forms either side of the harbour bridge.

Its kind of a big reminder that nature is in charge, when a cold front can close SH 1 in the heart of our major city so easily.

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Equinoctal storms have been with us for ever. A high harbour bridge taking trucks that are larger, longer, with a larger area than ever before of flat sides, ( possibly lightly loaded? )  into a prime (high) position for such an occurrence to happen. What is unusual is that it hasn't happened more often.

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1 hour ago, darkside said:

I guess that's one of the reasons trucks aren't allowed on the clip ons

that was due to loadings on the clip ons, not the blow over risk. I notice these days plenty of trucks use the clip ons.

Neither the original bridge nor the clip ons were designed for trucks up to 50t 

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4 hours ago, darkside said:

I guess that's one of the reasons trucks aren't allowed on the clip ons

Trucks/buses can you use clip ons, They were banned while rust repair work was carried out,

  • Mid-June 2009: trucks were allowed back onto lane 2 of the clip-on as strengthening work progresses
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Here's a screenshot of the Predict Wind observation graph for the RNZYS station. Shows gust of just over 50 knots just before noon. I don't sail the area often, but gusts of this strength are not that unusual for the location?? Surprised there isn't a high wind warning system on the bridge to prevent this from occurring??

 

gust.jpg

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Id have to say that as that is a support strut for the center span, and the outsides are the "clip ons", that the entire structure is likely compromised, not just the center lanes. The clip ons remain open....

I hope the engineers have this right!

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The clip ons go direct to the bridge piles, they are separate structures.

In saying that, they needed a load of work to address cyclic fatigue. That was when trucks were banned from them. I understand they were welding / re-welding a load of structure in the internal clip on cavities (box girder thingees).

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13 hours ago, Fish said:

The fact that these trucks rolled very close to where that micro burst nailed Westhaven, laid flat a super yacht, sunk some boats and made a cat flip and jump the pier is interesting. I'm starting to wonder if there is something unique about the geography there that creates down bursts. Wind accelerating off the land, or channeling between the land forms either side of the harbour bridge.

I live out west and was working from home on Friday. A wee while prior to the harbour bridge incident an intense front came through my place. It was already 20-30, but for a few minutes blew much more - like double or above. I'd say its not the geography around westhaven or the bridge, it was just a particularly intense front, which Auckland has always had come through. Unlucky that the trucks on the bridge happened to be there as it hit. 

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I wonder if NZTA have actually started moving on the repair. If it is only the strut to be replaced, then a concerted effort working around the clock in fab shops (might need to find some imperial tape measures😄 )and installation could see the fix in place in 10-14 days. NZTA's forecast of 5 weeks plus says either they are incapable of moving quickly or there is more damage than published

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Yes days on it would be good to think that the meetings and discussions have finished and that the fabrication to engineers drawings has commenced -it would have elsewhere in the world. Who do we ask that straight question to ?

These bursts do happen fairly often in Auckland only six weeks or so ago we had a good one during rum race, all were laid flat for about four minutes with some sail damage, on a Friday afternoon as well . Then back to benign conditions.

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I'd think that one of the pollie parties would sieze on this as an election issue.

It surely is something of national importance - when the biggest motor in the economy develops a knock, and we are as Lateral puts it, paralysed, that is the real problem. BUT whoaaaa - this is the wrong place for that discussion and may even a thread drift.

I saw/heard a report indicating engineers have to consult/design/peer review etc, and while we all want things done well, it seems farcical when u consider how long has the bridge been up for. What they did back then seems to have been ok and it probably took a ship load longer to do it with old school technology.

Any engineers out there care to comment?

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18 minutes ago, Romany said:

 

Any engineers out there care to comment?

Jeez why ask them when they could just get you guys to do the job.  Personally I would prefer the job to be done properly rather than the quickest patch up fix with Cheapest Chinese Steel and Cut Corners.

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