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from the details-matter-even-really-little-details dept.
The root cause of the collapse of Baltimore's Francis Scott Key Bridge when hit by container ship Dali has been identified. It was the wrong placement, by a few millimeters, of the label on one wire. As usual, the National Transportation Safety Board has taken their time and done a detailed investigation--summarized in this short video
https://www.youtube.com/watch?app=desktop&v=bu7PJoxaMZg
tl;dr - the wire was not completely inserted into a terminal block, due to the wire label wrapped over the ferrule. Over time the connection became intermittent and eventually shut off power on the ship...after which it drifted into the bridge. Of course there were additional contributing problems as well.
The YT video comments include some more interesting details.
[Ed. note: For those not inclined to watch the YouTube video, the narrative summary of the video is listed in the spoiler below.]
1. The Dali electrical system distributes power and control signals throughout the vessel.
2. The control circuits contain hundreds of terminal blocks that organize thousands of wires.
3. The wires on the Dali were terminated with metal sleeves called ferrules that allowed for easier assembly into the terminal blocks.
4. Each wire was identified with a labeling band.
5. This image shows several terminal blocks on the Dali with wires connected.
6. To assemble a wire into a terminal block, a tool inserted into a side port opens a spring clamp, which allows the wire's ferrule to slide into place.
7. Removing the tool closes the spring clamp, securing the ferrule firmly against the terminal block's internal conductor bar.
8. Labeling bands identify wires and are typically positioned on the wire insulation.
9. However, many labeling bands on the Dali wires were placed partially on the ferrules, which increased the ferrules' overall circumference.
10. As a result, during vessel construction, some of the ferrules could not be fully inserted in the terminal blocks, including the ferrule on wire 1 from Terminal Block 381.
11. On that wire, the labeling band prevented full insertion of the ferrule, so the spring clamp gripped only the ferrule's tip, resulting in an inadequate connection.
12. Due to this unstable connection, over time the ferrule on wire 1 slipped out of the spring clamp to rest atop the spring clamp face, resulting in a precarious electrical connection.
13. When a gap occurred between the ferrule and the spring clamp face, the electrical circuit was interrupted, leading to a blackout on the Dali.
(Score: 4, Funny) by krishnoid on Tuesday December 02, @12:13AM (10 children)
Dear God.
I worked at a company that produced physical products that had to comply with federal regulations (remember those?), and one of the documents indicated that you should report non-compliant "signage" (or something similar). I was confused and feeling a little ornery that day, so I called and got ahold of a person and asked how "signage" could be defective or a regulatory compliance issue. She replied that a label could be in the wrong place, the wrong size or the wrong size font.
I thought, "Ok, I guess that makes sense, but it seems a little like overkill."
(Score: 3, Informative) by Anonymous Coward on Tuesday December 02, @01:09AM (9 children)
Where I work we make communication equipment mostly for military, and some satellite communication companies. We're quite strict with everything, including labeling. I don't mean to be mean, but some of the people who will install and use our equipment are not the smartest nor highest trained people. Mistakes could very well cost lives. So yeah, labels and signage could be very critical. Sometimes it seems almost silly when it seems like there's no way someone could mess things up. But our equipment might be going in with many other kinds of equipment, with possibly the same connectors, and mixing them up would cause major failure of many systems. Hopefully people rest a bit easier knowing that somewhere someone is doing things right and well.
(Score: 3, Insightful) by krishnoid on Tuesday December 02, @02:21AM (3 children)
The (U.S., and probably others) military is sometimes the best option for children neglected/underprovided for by family, society, and the educational system. If "not the smartest nor highest trained" are otherwise staring down the barrel of a dead-end job (or a life of crime) since they won't be going to college, they'll find themselves in an environment within a domain of the more complex machinery we have in the country -- coincidentally, which is designed around killing people and damaging harder targets.
I'd say unambiguous labeling gives the loving, caring drill sergeants something to point to while they're yelling at a recruit as to why they screwed up on something that could kill people. If "not the smartest nor highest trained" recipients can get the sense that someone didn't really care when writing up the signage [schlockmercenary.com], they'll also get the impression that materiel suppliers don't care either, which I suspect propagates an attitude (around weaponry and in combat zones) that could eventually kill people.
(Score: 4, Insightful) by JoeMerchant on Tuesday December 02, @03:18AM
> could eventually kill people
I suspect it's more a case of: numerous GAO studies concluding that expensive injuries and deaths could have been prevented with better / less sloppy labeling and that the cost of such labeling, being less than the cost of disability benefits for 50+ years, is a worthwhile investment.
🌻🌻🌻 [google.com]
(Score: 0) by Anonymous Coward on Tuesday December 02, @03:27AM
OP here. Great insight, and you're inspiring me to think about military personnel morale, and doing anything I can to inspire them to realize how important their work is, and to take pride in doing good work.
(Score: 0) by Anonymous Coward on Tuesday December 02, @09:53AM
On a related note: https://maritime.org/doc/neets/mod04.pdf [maritime.org]
See also: https://hackaday.com/2017/06/09/electronics-education-courtesy-of-the-us-navy/ [hackaday.com]
https://electriciantraining.tpub.com/14176/css/Rattail-Joint-47.htm [tpub.com]
(Score: 3, Interesting) by PiMuNu on Tuesday December 02, @09:25AM
Many situations where incorrect signage is very dangerous. Repurposing bottles comes to mind as a way to quickly kill people.
(Score: 4, Insightful) by VLM on Tuesday December 02, @02:41PM (3 children)
My personal experience (and I'm not offended) is everybody's smart, until they're awake 24 hours or standing outside in the snow or just made a 15 mile march or they've been doing this for the last 12 hours without a break. Thats when people get pretty sloppy. Labeling helps. Like how paperwork has a standardized explanation and format so you can do it in your sleep, because sometimes you are half asleep...
(Score: 3, Interesting) by hendrikboom on Wednesday December 03, @03:05AM (2 children)
My wife was a doctor.
One night she was on call.
That means the hospital can call her at ungodly hours to advise on the treatment of a patient.
One morning when she got to the hospital she inquired about the status of a patient.
She was informed that the treatment she had recommended in the middle of the night was working.
She had no memory of being consulted during the night.
She concluded that despite being sleep, she must have taken the call and advised the right treatment despite never having woken up.
Scary? Or an indication of extraordinary competence?
(Score: 2) by RS3 on Wednesday December 03, @04:23AM
A little of both maybe? But I do all kinds of things every day that I don't remember, so I wouldn't give it much worry. Now where'd I put those darn keys...
(Score: 0) by Anonymous Coward on Thursday December 04, @02:58AM
> She had no memory of being consulted during the night.
Some similarity to something that happened to me 40 years ago?
I was in a minor accident, slightly concussed (lost memory for a short time) and was transported to the local hospital ER. Took awhile to get into a room at which point I was seen by a very attentive young intern (not yet an MD). He got me some x-rays and kept me overnight for observation. There was also a night nurse, an older tough cookie who (correctly) kept waking me up every half hour, based on the concussion.
A few weeks later I got a bill from an MD's office, along with the MD's report on his examination of me and a totally fabricated "transcription" of his conversation with me.