from Hacker News

‘Significant overload’ caused Norway’s timber bridge collapse

by mjmasn on 12/8/22, 12:46 PM with 70 comments

• by silvestrov on 12/8/22, 1:42 PM

  The homepage of the "Norwegian Safety Investigation Authority" is much more informative and the 2 documents have interesting photos, e.g. closeups of where the wood broke.

  https://www.nsia.no/Road/Investigations/22-441

  It does not state why they conclude the cause was overload, only that "Uncovering the technical causal factors for the collapse of the Tretten bridge has been challenging. The expert group has worked its way through several hypotheses to be able to exclude non-relevant fracture mechanisms, by connecting findings to computational analyses. There was significant consequential damage to the bridge structure, both from the collapse itself, the impact with the ground and the salvage work, and it has been challenging to separate these from each other."

  Personally I would think that a bridge should be able to handle "A passenger car and a truck with trailer loaded with lime were on the bridge when it collapsed".

• by mywittyname on 12/8/22, 3:39 PM

  Building Integrity on YouTube is a fabulous channel to watch if you're interested into deep dives into failures such as this. The host is a civil engineer who specializes in performing structural audits of older buildings (specifically condos, I think).

  He did a an episode on this bridge. It is excellent, and it provides some context about other timber bridges that is not discussed in this article.

• by GeompMankle on 12/8/22, 2:19 PM

  I think a fairly good argument can be made that the design of this bridge was novel to the point of being negligent as per https://www.youtube.com/watch?v=FSPI0xkTifI

• by rch on 12/8/22, 2:47 PM

  > head of the Centre for Wood Science ..., identified steel truss issues as a possible factor.

  You don't say...

• by thordenmark on 12/8/22, 2:50 PM

  I frequently cross the Golden Gate bridge. This is my nightmare. Can you imagine plunging to your doom if that bridge failed? Yikes!

• by pornel on 12/8/22, 6:54 PM

  Can someone provide background on this — what makes this accident and/or bridge notable?

• by londons_explore on 12/8/22, 5:25 PM

  TL;DR: One of the diagonal beams was only designed to be half the strength it needed to be, and it snapped.

  This type of bridge needs every beam - so when one broke, the whole thing fell.

  The mystery really is why it didn't collapse sooner - that's still under investigation.

• by hackrnusr on 12/9/22, 6:48 AM

  Can't wait until all of the timber skyscrapers that they're building to fight global warming meet the same fate.

• by numbsafari on 12/8/22, 2:52 PM

  It'd be neat to integrate ChatGPT into a "bridge builder simulator" type game, and have it generate post-mortem news reports like this one for the bridge failures.

• by tpmx on 12/8/22, 5:18 PM

  Well, then it was underdimensioned.