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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, 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.