What Really Happened at the Hernando de Soto Bridge?
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- Опубликовано: 14 июн 2021
- In May of 2021, inspectors on the I-40 Mississippi River Bridge near Memphis, Tennessee discovered a major crack in a structural member. They immediately contacted emergency managers to shut down this key crossing to vehicle traffic above and maritime traffic below. This video provides a summary of the event, including a discussion on arch bridges, fatigue in steel members, and national bridge inspection standards.
Errata:
(1) 8:38 "at minimum, an arm's length away" should be "at maximum, an arm's length away"
(2) 1:14 New Madrid is usually pronounced MA-drid, not ma-DRID.
(3) 4:55 ”It’s hard to understate the severity” should be “overstate”
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Some imagery provided by ARDOT and TDOT via Twitter.
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Producer/Host: Grady Hillhouse
Assistant Producer: Wesley Crump
🚧New studio - who dis? Sorry about the audio quality and stark white wall. It’s a concrete box that is also a work in progress.
👷 My coverage of other engineering events: ruclips.net/p/PLTZM4MrZKfW_kLNg2HZxzCBEF-2AuR_vP
Your studio is inside a tornado shelter?
@@ljviks22 Just to clarify, the inspection team that called 911 was not responsible for inspecting anything below the deck. They were hired to inspect the arches and hangers and just happened to notice the fracture on the tie. ARDOT uses internal inspectors for the portion of the bridge below the deck.
Just as an FYI, "New Madrid" isn't pronounced like the city in Spain. It's said like "MAD-rid", just like how Cairo, IL is "KAY-roh" and Athens is "AY-thins" in several places in the American midwest and south.
@@ljviks22 The team that found it wasn't responsible for checking for it. They appear to have gone above their job to notice and report this. The opposite of incompetence.
@@ljviks22 Sorry brother, the team that acted swiftly was very responsible and competent. It saw a crack in an area outside of the premise of their work, and called 911 instantly. The teams that missed the crack are the in-house team. And as brilliantly explained in the video, firing someone is not the answer. Your inspection process is bad since a mistake than can make the whole structure to collapse is let to a single person. We engineers know that humans are responsible for errors and mistakes. So we create processes and workflows that erase or maximally minimize their occurrence. So firing someone is not the answer but "firing" the process and making a new one is the good step.
To the inspector who bypassed his boss, bypassed his client, and went directly to 911 to get the bridge shut down ASAP... your efforts to pass the Engineering Ethics course paid off, right there!
That's one of the first things I thought too. Knowing the system, the guy probably will get fired for making someone look bad (read the book by the Thiokol engineer that went public with the shuttle O-ring problem at low temps - the only thing that saved him was Congress threatening Thiokol with loss of future contracts if they took any action against him). What should be the norm is the unfortunately the exception.
@@JimAllen-Persona been there, done that
He will probably be reprimanded since he claimed the Glory.
The proper thing to do is make that person head of bridge inspections. The romans had a good method of ensuring engineers knew their job. The architect was made to stand under the structure while it was over loaded. Same should happen now to the Board of directors and the MDs once a year.
@@walkerig1 That is so brutal and archaic, but somehow such a beautiful process.
"If your ability to identify a critical flaw relies on single person, you have a much bigger problem than the current critical flaw" - extremely well said.
Indeed!
I work in a field where this sort of stuff is sadly common. Good to hear someone draw attention to scapegoating one person for a multi-level failure. Even if that person did fail, he shouldn't be in the position where his failure can have such a massive impact.
That was my first thought when I heard "one person" was fired. Wonder how many others are being protected?
I wouldn't be surprised if the guy who got fired tried to/did report it to his superiors and just got ignored or forgotten.
I agree! This should become a famous quote. No excuse to leave that many lives in the hands of a single inspector/person. Always cross examine critical systems and structures when lives are involved. In my opinion based on the known facts of the situation this company should be held responsible for there negligence in the matter of cross examination. Too many examples in history of catastrophe and lives lost from failure to simply double check or have a fail safe system in place and yet this company has seemingly made that same mistake almost to detrimental outcome. Somebody simply watching the video that the inspector captured as a second opinion would have be enough in this particular situation. This is one reason why the hands on inspections exist and are enforced... it almost definitely saved many lives in this scenario. So glad this situation didn't end up being another page in the history books of lives lost.
I love how he politely and professionally roastes the company for blaiming a single engeneer. He is right you cant blame just one person for that mistake.
It wasn't a company, it was a gov't organization. Even if the person was a contractor, the inspection was the responsibility of ARDOT.
@@tlbfarm4473 news flash, if ARDOT highered a contractor for the inspections they have fulfilled 90% of their obligation as the company is considered qualified to do the inspection
@@itptires True but something like a bridge that's used to safely transport human beings would normally require a redundant inspection method. One inspection by one contractor is never enough.
@@heathwirt8919 The problem with redundant inspection is that each inspector may start to think, "It's OK if I slack off. the other inspector will catch any problems."
@@rk4397 That's not true, in fact it decreases the chance of a missed defect exponentially.
Just for those asking: The bridge is now totally open as of August 3, 2021. Repairs were made and the bridge was reopened ahead of schedule.
"Ahead of schedule"-sounds like the Government wasn't in charge.
@@havenhemmings3574 You are absolutely right!!
@@fredfranklin8816 LoL 🤣😆
Translation: ArkDOT and TDOT just slapped a band-aid over it and swept the incident under the rug, hoping everyone will forget about the whole thing.
@@MrChugwater A good coat of paint will fix that bridge up real good!
A professional engineer doing something so "non-engineering" as making youtube videos that are comprehensive and understandable. A truly talented fellow! Thanks for sharing your talents.
Stuff Made Here and SmarterEveryDay are two other channels you might like if you liked this. They're both more hands-on engineers where Practical Engineering is more informational. Some example projects are the making of a .50cal baseball bat that can hit 700+ft or going on a navy sub and explaining some of the cool tech/engineering they have to use and how they operate.
I think you underestimate how much of an engineers time is spent making things "easy to understand" for people who are smart with authority but limited knowledge of the field you are in. The ELI5 model should be applied to everything not directly shared with your peers. The engineers who cannot do this often hit a glass ceiling in their careers regardless of how "smart" they are.
@@trepidati0n533 Interesting insight. I was about to say, I think it shows a lot about Grady's intelligence (and the other engineers capable of this) that he can make these videos for us in an easy-to-understand manner.
nice profile pic
@@trepidati0n533 A lot of engineers wish they had hit that glass ceiling when they realize their job is no longer engineering, but rather sitting around stroking the board's egos in return for funding.
Interesting that there's so much evidence the checks were not performed properly on previous occassions. Glad it was picked up before catastrophe though.
I guess you could say that the check procedure was successful as they did find the crack before the bridge collapsed. However it was probably the last chance and it would have been better if earlier checks had picked it up!
I am shocked that something run by the government would have this many flaws. I mean, rarely does the government mess up anything.
@@OffGridSupplies ultimately successful in that regard, no one was hurt. But the crack is visible since at least 2016 from the water?? Huge failure nonetheless.
@@bruceadamsjr.2901, way less frequently than private enterprises do. Literally orders of magnitude less frequently.
@@Vessekx have you heard of this think called the post office? How about immigration and customs enforcement?
I’m a truck driver and I crossed over that bridge many times in 2020 and early 2021. Scary to think I was loaded going over something like that. Thank God no one was hurt.
Same. I’ve always hated going over bridges in a big truck. In 2001, it was decided we need a new bridge over the Ohio River between Henderson, KY and Evansville, IN. The twin bridges used currently are quite old. It’s now 2022 and no new bridge construction because the 2 states have spent 21 years arguing over who’ll pay for it.
@@stevennewman4778 ouch 😬. They should just split it bc that can turn into something super dangerous especially if it’s a taller bridge
How many times I have SAT on that bridge during construction in Memphis.
It makes me happy to know some disasters are avoided by stubborn insistent individuals. People that put their foot down and demand things to be shut down. These people need to be publicly praised and rewarded to encourage people to speak up more often.
Good on the police for simply accepting what they say too. Block bridge first, ask questions later. They could've easily been arses about it and told them to pound dirt until something more "official" came their way.
I know a failed Austrian art school student who was encouraged to speak up more.
@@spacejihadist4246 You know of him, but you don't know him.
Sadly, more often than not they are harshly punished even when they are right.
I'm glad that this made Practical Engineering and not Seconds From Disaster.
Would make an interesting video on "Plainly difficult"
I'm glad there was no collapse, like what happened on the I-35W bridge.
I dont know that channel but i believe i can infer what kind of topics they discuss from the name and context. Lol. I do know Plainly Difficult though.
@@the_original_Bilb_Ono @Sakke K Funny y'all mention Plainly Difficult because I just find and subbed to him a few days ago. @Nate Jones Likewise. Imagine the local commuters who use that bridge every week. One day you turn on the local new and find out you were driving over a metaphorical trap door to your death.
Or fascinating horror
I'm glad this topic was covered by the channel Practical Engineering and not the channel Fascinating Horror.
I was thinking the same damn thing!
Underrated comment.
I was thinking the same thing lol
Hey it's you!
Thanks for the minecraft 1.2.5 ctm maps you were making! I got a lot fun going through Spellbound Caves and Sea of Flame II
@@msergei98 Spellbound Caves II (featuring the official Super Hostile Modpack) should be out in 1 to 2 months, so be sure to check out my discord for updates
I live in West Memphis. This bridge is vital to our community and traffic was a nightmare for 2 and half months. Im glad to say that workers worked around the clock to get it repaired. Both lanes east and west bound are now OPEN!!
How much back log on the river was halted?
I wouldn't trust that bridge regardless.
@@r.d.9399 :
@@r.d.9399 m
@@r.d.9399 I would . IT has probably been inspected and checked far more times since this happened than when it was new. THere are literally THOUSANDS of bridges in worse condition on our roads. Note - the crack did not appear to even be rusted much. THere are LOTS of bridges designed just like that one all over the country that do not have cracks - and we can thank that bridge for getting them ALL inspected better.
Love the whole tenor of these videos. Calm, logical and just wonderfully explained. I wouldn't have minded this guy as a science teacher in my youth.
Hurrah!
Grady, really appreciate your emphasis on the fact that we are human, and humans make mistakes, so we need processes to account for that.
So often an individual is blamed for such an incident...and while individual performance can have disastrous consequences, it takes a team to properly execute something of the magnitude of a major bridge inspection. It seems that in recent history corporations, as well as state and federal entities, are all too often under severe budget constraints and cut manpower to dangerously low levels, placing undue burdens on individuals to "not make mistakes". I miss the old days before the breakneck speed computerized era, where you were forced to preform tasks at a more thoughtful pace and utilize checks and balances, as well as stand back and look at the big picture from a common sense perspective.
@@tallbikercat This wasn't a "mistake". The crack shown in the drone footage was enormous and obvious. All it would take to spot it is for somebody to actually look at it. Some inspector pencil-whipped the safety check while lounging about on the job.
good management is recognizing that humans aren't perfect and that its the processes, systems and oversight that fail
@@chrimony exactly, It's like an equity researcher not actually looking at the company's financial statements, it is so essential to the function of your job that it seems like an individual is to blame, even if there should be more QC
Properly designed quality control processes should account for the fact that a portion of the work might be carried out by flawed humans, some of whom might be incompetent, tired, careless, reckless, or intoxicated. Cf. Exxon Valdez.
you KNOW something is bad when an inspector bypasses all of his superiors to call 911 to shut down major infrastructure.
Can you imagine the repercussions if that kind of call was made and it turned out to be a non-issue. Making the decision to make that call is honestly a huge deal.
@@austinwolfe7295 I'd say the opposite; if it even had the appearance of being an issue, closing the bridge immediate is the only prudent option until it is ruled out as an issue. And the inspector would definitely know the difference between an "oh shit" situation and a "let's file a report" situation. Also... depending on the situation, there is probably professional licensing involved that could make the engineer('s firm) liable for massive damages if the standard of care isn't met.
@@austinwolfe7295 yeah though I can hardly imagine fracture-critical piece cracked completely being non-issue
I'm still trying to imagine the 911 conversation. "You want us to do what now?" "Shut down the bridge!" "Say again." "The bridge is in danger of collapsing!" "Is this a prank from some kids? You know you can get into a lot of trouble." "No! This is Jim with X company I am inspecting the bridge and it is danger of imminent failure!" "Uhhh...hold on let me get my superior. We don't have a procedure for this..."
@@dbrobb5282 The 911 calls were released early on. The call to Arkansas 911 got traffic from that direction stopped. The call to Memphis 911 went pretty much like you said. I don't know the final outcome but there was some significant reporting on the 911 response (lack there of) right afterward.
I used to operate a drawbridge and the inspections were laughable. Those guys never took it seriously and glossed over all the issues that were visible to anyone. I have no idea how there are not more tragic incidents. Thank goodness in this case a good person finally looked at this bridge.
As an inspector it helps to know that you have to inspect 1k’s of things, and with to few people and way too many things to check thing get missed I appreciate that you pointed that out. The real issue is under funded, over worked inspectors.
Your lack of attention to detail and acceptance of mediocrity does not inspire confidence in your ability to speak on behalf of other inspectors.
*Thousands not 1k’s
*too not to
*things not thing
If there is not enough time or people to inspect something properly, then why bother at all?
Underfunded and overworked? You don’t know anyone in the medical field do you.
Inspectors of this magnitude (national or international infrastructure) must understand the critical importance of their jobs. I’m only responsible for a piece of our national grid, but I know that barring an environmental change, there are no transmission lines in my territory at risk tonight.
Managers who have never inspected telling inspectors how to do a job. Managers get paid bonuses to not spend money that is a conflict of interest, manager should be paid based on successful operations
Your inability to put together a sentence without major errors gives me reason to doubt your claim. Inspectors are detail-oriented people. You do not appear to be such a person.
@@johncrafton8319 you sit at desk or have no job and would be a poor choice as a manager since you spend so much time looking at leaf cells then miss the forest fire good luck in real life you will need it
@@jamesocker5235 Exactly the kind of reaction I'd expect from someone such as yourself - an attempt at projection from someone ignorant of the subject matter at hand.
Engineers, inspectors, designers, technicians - anyone from the STEM fields, really - know better. Without a detail-oriented mind, you simply cannot survive, much less succeed, in such a job.
Your attempt to attack me for calling out the OP only proves to show your own lack of understanding.
“I am thankful that those motorists are still around to be inconvenienced”……. almost poetry.
Do you live in the Memphis area?
@@joeb134 What’s that got to do with the price of fish? I’m in Cincinnati and our major river crossing was shut down for a month after a truck caught fire, and is currently down to half capacity as they repaint it.
Yeah, traffic sucks, but you know what sucks even more? Having people end up dead because of an entirely preventable collapse. Cause if you think investigation and repairs take a long time, imagine how much longer it’ll take if they have to build a new bridge from scratch
@@joeb134 and what does that have to do with anything? Are you saying you prefer driving in the river when that bridge suddenly and catastrophically fails, so long as it means you got another month of driving across it?
@@joeb134 “Walk a mile in my shoes” is “catchy” but that’s all. I don’t need to walk a mile in anyone's shoes to appreciate, even comment, on ANYTHING. Of course, you are due SOME slack given your surname.
They may be alive because of an inconvenience. Won't stop them complaining though.
When I studied civil engineering, it was repeatedly stressed that while doctors might kill, engineers kill in bulk. This was a lucky break indeed, to invoke a truly awful pun.
True. There was an operation in recorded history with a 300% casualty rate but that was the exception.
I'm not sure if it should make you feel better that Electrical and Computer Engineers, and some Computer Scientists, have also been told roughly the same thing...then shown evidence. Unfortunately, some needed it to be explained to them why we should not design things in such a way as to make it very very very easy to do incredibly dumb shit.
Physicists and chemists meet that standard as well.
@TheDowner aye but it pretty tho
@VeryCleaverName Where are you getting those numbers mate?
You are also superbly effective in stating the troubles *very firmly* yet without "over-emoting". Your calm yet stern directness deepens the impact.
As a truck driver who has crossed over this bridge many times in the last 7 years, I’m thankful it didn’t collapse. Definitely glad you also talked about the inspection prior that missed it. I remember for a while there they had a lane closed for either inspection or repairs to the bridge so how could this be allowed!
9:50 Every company when they failed some critical section. "We fired that guy, now it is ok".
Scapegoat *cough*
I hope that guy followed CYA protocols, cause dollars to donuts they likely were trying to get management to fix the issue.
Someone always has to get thrown under the bus for PR purposes.
Inspection job should have rotated to avoid 'innocent' mistakes/single person errors, and incidentally catch willful blindness. This makes me wonder if the inspectors were told what to report in advance by management, and what level that decision was made. (ex: was an elected official raiding the bridge maintenance funds and dictating this?)
"Unless someone is injured, it's not a crime. Even if people were to get hurt, we'll just resign."
@kstricl actually it was the inspectors fault entirely the inspection team noticed it on several inspections but the inspector chose to keep approving the bridge. It was entirely the inspectors fault. Hence why they fired him. That guy shouldn’t be allowed near a bridge for the rest of his life in my opinion.
As a former construction inspector, I can’t tell you how many times I’ve inspected something, found problems, and they were completely ignored due to time and money. When a failure occurred everyone walking around like they didn’t know about it pointing fingers until my report resurfaced and it shut everyone up.
yup. I had the same experience with WSDOT.
That is so sad, but true... And believe me it's not time and money it's ignorance
My first job as young engineer on a construction site lasted only 3 days because I discovered big problems and demanded rectification. They asked me to cover this and wait after the reception so they can have the bonus of finishing on time. I refused to sign the quality report and I left . They didn't care that the tall building was in earthquake area and that the soil was full of water because of the defective drainage or that some beams were shaved of to fit the bay windows ( somebody did a mistake when ordering)...and so on. And it was Bouygues construction, not a small enterprise.
@@agalie7139 Yep! That sounds right. It is a shame they do those things. I had to quit due to extremely long hours and the mental stress. Most being arguing with contractors about doing their job right.
that's reality how employed people earn their money, they learn to shut up and just do the job...and it is makes sense, why bother to seek justice while the CEO is the person who will sign the approval
4:07 that is literally the exact question that popped into my head when starting this video. It's so satisfying you answered it so specifically, I'll never forget the importance of the road deck itself now.
Edit: I love how you're saying that we need go after systemic problems instead of finding individual scapegoats.
I am still amazed at the depressingly rare but stunningly courageous, competent and confident action taken by the engineer to immediately make the call to close the bridge. The founders of Galt’s Gulch would be proud! No hesitation, no need to escalate to someone higher up. No need to consider the irrelevant impact on east-west traffic, nor north-south shipping. See the right thing, do the right thing. Huge kudos!
anytime you close a bridge over the largest river in the country to traffic beneath and across it, that’s not irrelevant. Especially since Memphis is the largest population center on the river.
@@joshuapatrick682 If he didn't close the traffic, it was a question of time - perhaps months, but perhaps only minutes, and there's no way to know ahead of time - before the bridge itself would choose to close that traffic. By collapsing, which would, obviously enough, inevitably kill people and put a larger disrutiption into traffic - making that an irrelevant point of consideration.
@@joshuapatrick682 we need fewer people who think of lives saved as less important than lives that are mildly inconvenienced. Whatever you had that was inconvenienced is nothing in comparison to the lives of children that could have been lost. Get over yourself.
@@EgorKaskader and to the other commenter. Think about the person making the call: that could potentially cost them their job which today is a huge decision to make on the spot. No wonder people will go through the specified chain of command when it's urgent like this. I highly doubt either of y'all would have made the same call if you were in the same situation *with the same skills and industry experiences*. Many people who've never seen what it's like on the inside don't know that making a call like that can lose you your livelihood. So while yes these men absolutely should be commended for being quick, don't look down on the man who did it through chain of command. This would be an extremely stressful situation for anyone to be in. They don't have the time to think about the ethics of each version unlike us.
I actually expected him to explain why this isn't such a big deal and leave the video feeling confident in bridges, but now I never want to cross one ever again.
Bridges are an affront to nature and should have never been invented. Some barriers are just not meant be crossed.
just know that you probably have a waaaay better chance of being struck by lightning than actually being involved in a bridge failure, even with the small ones
I will not let my wife see this video, she already freaks out when ever we have to cross a bridge of any size.
It's fine, most people leave bridges alive most of the time. Unfortunately 'most' is not 'all,' but it's pretty damn close in this case.
Wait until you realize states get bigger bucks for repair of their bridges are left in disrepair
The FIU bride collapse ended many lives. When you say “I’m glad those motorists are still around to be inconvenienced” I felt it.
That bridge killed some folks about 20 years ago!
@@46bovine It collapsed in 2018?
I feel sorry for FIU's husband.
@@46bovine Most prolific killer bridge in the world.
Many who are inconvenienced would not think of that, they will just grumble away and not concider the consequences if they were crossing at the time..
That’s a huge fracture! I'm glad the inspectors took it on themselves to call 911 immediately. I can imagine that the call to shut the bridge down ruffled a lot of feathers, but clearer heads prevailed this time. It makes you wonder how many other bridges have been inspected as recklessly as that bridge obviously had. Thanks for sharing this with us, Grady.
I never thought i would be fascinated by an engineering channel, but i find myself glued to each episode - you definitely have a gift of being able to pass this information onto the average person - thanks for sharing
You should take a look at the stuff that worksafeBC puts up at utube. Also, USCSB. Fascinating, and . . . troubling of course.
Me, before the video: "Just how bad was it, really?"
Me, after the video: "Oh, oh dear..."
Imagine my shock, being a trucker who had driven over that bridge just a couple weeks before it was shut down. I've also driven over it, sometimes close to 80,000lbs, many times in the past five years. That thing could have given way at any time.
I never liked bridges, but this situation didn't help.
*chuckles* I'm in danger.
@@yankeedude252 They fired the inspector who missed the crack that he documented, basically to motivate future inspectors to not document their own errors. This way the bridges will become even more insecure in the future.
@@TremereTT I think you've got that series of events wrong. They have documentation that the person who got fired was the person who inspected the bridge (or signed off on the inspection) but the video doesn't say that person documented anything anywhere. They might well have been a different person (and probably are) than the one who caught the crack on drone footage.
@@CSpottsGaming of the people who caused the three mile island desaster no one was fired, instead everyone who was part of the chain of wrong decicions contributed to the investigation in order to prevent these wrong decisions in the future.
It's not good to fire people for having botched something in the past.
It creates a theater of fear and encorrages cover ups among the people that stay in the job.
As someone who is not an engineer, this was an easy to understand breakdown of the I-40 bridge issue ...great job!
The name of the person who claims he missed the crack should be published so that the next perspective employer won't make the mistake of hiring him
@@PurpleObscuration who claimed he missed the crack? If the whole company missed it, no specific inspectors or every of them are to be blamed. As they inspected the bridge with drones, it's a lot easier to miss a crack, the drones operators on the bridge have poor visibility and those who watch it later have hours of shots to inspect : human error due to a combination of factors.
The company still made careful inspections, because the crack was found before it's to late, but they should have been more aware and do it every time.
In fact it's the best end : lessons will hopefully be taken, and no one was injured.
@@PurpleObscuration
Umm why did you leave your last job?
We couldn't see eye to eye.
How did you leave,
They didn't need me anymore.
Can I have your last employer name?
Unfortunately they can't say anything.
They can't even ask. All they can ask is was he employed from to from?
So glad the crack was found. You did an excellent job of going over he information with us. Thanks!
My family and I were detoured across the I-55 bridge in late July going from OK to SC and back, and I had wondered why the I-40 bridge was closed. Thank you for this!
"I'm thankful that they're still around to BE inconvenienced." This is my favorite line from this video.
Same here. I just wish people felt the same way about covid.
*Practical Engineering:* _"Structural engineering is not an armchair activity..."_
*Me, an Armchair Engineer:* _Silently nods head in agreement._
@Great Value Bleach 200,000 units ready to deploy, with a million more well on the way
Me: I wonder how the steel was distributed down the North Tower of the WTC before 9/11. I have not heard any structural engineers discuss it. - Armchair electrical engineer
@@psikeyhackr6914 jet fuel can’t melt stale memes!
@@trent_k wasn't talking about melting steel. Was talking about distribution of steel. Did the 5th level contain the same amount of steel as the 100th level? The potential energy cannot even be accurately computed without distribution of mass.
psikeyhackr the steel was distributed vertically.
The fact this is only the Hernando de Soto incident, and not the Hernando de Soto disaster, is honestly truly fortunate.
crazy to see a video on this, my grandfather did the steelwork for the bridge back when it was first built and it makes me smile everytime i pass over it remembering him
I love that there's video of the crack during the last "inspection"
How do you miss something like that?
@@tripplefives1402 Thanks for the info mate! It helps explain why it wasn't picked up. Still a marvelous example of "it's not my job" attitude. The crew inspecting the arch, if qualified enough to inspect the arch, should be also aware that a fracture in the beam is a critical failure element.
But anyway I just wanted to say thank you for the information.
@@tripplefives1402 That is scary. Really scary. Sadly, it's how it is.
Being a former resident of Tennessee, and now living in an area that had a major Interstate bridge disaster (coincidentally, also over the Mississippi River) in the year 2007, I do hope that the people get their heads out of their asses and build a new bridge over that river, and/or build some additional bridges over that river as well to serve the area to ensure that there is at least one back up bridge that serves the area while the replacement to the Hernando de Soto Bridge is being built.
@@paxhumana2015 I was in MSP about a month before that happened. Watching the footage on TV was scary because I recognized the landmarks.
Superb job explaining the structural aspects of the De Soto bridge situation so thoroughly that even a laymen like myself has a very clear picture. As an OTR trucker, I've driven over that bridge hundreds of times over the past three decades. It is a relief that a bridge design like the De Soto is so overbuilt that even a major problem like the broken girder is not catastrophic. But it is very scary that the crack clearly visible in the 2016 boater photo did not result in the bridge being shut down for FOUR years. Makes me VERY concerned as I drive over MANY bridges all over the US every month, and cannot help but wonder how many other bridges may have unreported cracks that are growing larger every day. Thanks again for this SUPERB explanation.
Your video and your delivery were succinct, tremendously informative, and totally enjoyable. Some of these video guys just ramble on and on. I immediately subscribed. Thanks!
That is NOT a CRACK. That is a completely separated BREAK!
It was still connected at the bottom inside corner at the time of discovery. Probably wouldn't have stayed like that for long though.
Exactly
That is a fatigue crack that grew until the member fractured. Loads have redistributed and now other members are probably overstressed.
Stupid Kit Kat bars...
yea a freeze-thaw cycle or two and it would have been toast.
The only reason I didn't hear about this issue before this video is that the bridge didn't actually collapse. Thank You for compiling this for us.
Guess you don’t watch the news cause I seen it on every station
@@troypowders4312 you say that like it's a bad thing
@@troypowders4312 The world is not only USA.
@@troypowders4312 Are you local to this area? I also didn't hear about it but I'm not local.
@@tripplefives1402 Trust me everyone was talking about this bridge if it collapsed while being used.
Thanks for making these great videos. I have just a casual interest in physics and engineering but you make learning about megastructures and the forces which act upon them much more interesting.
Being Minnesotan, I can appreciate finding a crack and mitigating fixes ahead of time. Our 35w bridge collapse wasn’t something any metropolitan area should suffer through.
When more information arises, I think the recent Miami building collapse would be an interesting video idea
Except that has John McAfee ties
@@Sassafras- wait what???? where did that info come from? HOLY... did he kill himself after the collapse or before?
@@Outwars1 maybe he hasn't. anyway CNN already suggested global warming. lol.
@@justthink5854 Well if you look at what it's built on the increasing water levels on the coastal plain it was built on would definitely be related. Regardless if you believe in global warming it's still climate change. It's called science.
@@spateri728 CNN, etc. it's called non science. he's made 1,000's of these over the last 10+ yrs. but you have your religion don't you. ruclips.net/video/n5FojQ73SsQ/видео.html
The "we fired the guy who messed up" thing is cancer and people should push to not do business with any company making such a statement without making available the full investigation.
Working in manufacturing for over 10 years, both operation and quality assurance, the amount of people I've seen being used as scapegoats is insane, and since people wouldn't want to work for that company after the fact anyway, they usually move on with their lives without making it a big deal.
It's usually the higher-ups cutting down on equipment/staff, not listening to feedback from people doing the actual job and using outdated/unfit methods for the work required.
Well agreed. I especially like what you said: "making AVAILABLE the full investigation."
When you have a problem, and you find who's at fault, now you have two problems.
Agreed! Businesses can be thought of as collections of processes and policies that dictate how the business operates even as the individuals who do the work change over time. That means firing the responsible person likely isn’t solvent, because the next person will likely face the same challenges/constraints/expectations that led the prior individual to behave in an unacceptable way. Maybe the direct replacement won’t lie/cheat/cut corners, but without changing the processes and policies to encourage and preclude the unethical behavior, the replacement’s replacement very well may come to perform the same corner cutting/lying/etc.
Not a corporation it’s the Arkansas DOT inspector
Spot on ole boy. And you can magnify that when it comes to government jobs.
Those responsible for sacking the people who have just been sacked,
have been sacked.
This video has been the only concise explanation and assessment of the situation that occurred. Thank you so much!
Your a great story teller. I clicked on the video, never watching a video from you before, and was drawn in.
Very informative, learned a lot.
About to binge watch a lot of your videos.
Sincerely, a new subscriber.
As a Nashville resident who has crossed that bridge countless times, and as a science teacher who has many students dreaming of becoming engineers, this video was tremendously fascinating and enlightening.
Thank you so much. And ironically, my mother will be heading to Texas this coming weekend, and just last night I was showing her the I55 route to get across the river. So, the timing of discovering your video is also remarkable.
You have a great day sir.
We just moved here from Phoenix, and wondered why there was suck a huge amount of traffic being diverted there, and when our son drove here this week, we had him go around. Timing is everything.
@@caitlyndeambra2209 Welcome from Phoenix. It's almost as hot here as what you were used to out there, LOL.
Yes, normally the traffic is nothing like that across the bridge. Usually you just keep cruising at regular speeds.
Don't worry, once it's fixed it won't be that bad.
Take care.
Whether or not that tie qualifies as fracture critical, its failure probably makes whatever part took up the tension a fracture critical part now.
Yup, and that part probably wasn't designed for it, so it'll fail sooner rather than later.
Yeah that's the real thing here, that tie was very clearly carrying a significant amount of stress and that stress went somewhere when it failed
Dynamic structural classification. Even has an acronymn. DSC. Critical? Non critical? Well, it's undecided. I mean dynamic.
I’d say the deck is carrying the tension. It never would have been designed for it, but there’d be enough steel in it to do the job. It’s probably cracked a lot more now as it would be under tension. would be interesting to see if that’s the case.
Beyond the mechanical problem there’s the greater “NIMBY” problem: Not In My Back Yard, not on my watch, I’m not going to shut down millions of dollars of commerce, this will ruin my career, I’ll leave it for the next guy, etc., etc., etc….
One of the greatest, most important parts of any project is the human factor: integrity.
Unfortunately integrity is a rare commodity that can easily be corrupted. It's better to count on cross checking by 2 opposing companies,
SO TRUE!
This was my first time seeing one of your videos and I liked it very much. I learned a lot about this kind of engineering in a short time back in 2007 when the I-35W bridge next to my workplace collapsed suddenly. A Berkeley structural engineer named Hassan Astaneh-Asl came to town and we spent a lot of time together. Memphis got lucky. I drove under our bridge twice every day, and I had driven over it just a couple of hours before it collapsed. Someone I knew was on the bridge when it fell, but they survived while 13 others perished. There are hundreds of these fracture-critical bridges in the US.
And several more of those here in Minnesota have been replaced since then, starting with the Hwy 23 De Soto bridge in St Cloud -- which was like a smaller version of the 35W bridge, and had the _exact_ same gusset plate issues. Later was the US 52 Lafayette Bridge in St Paul, the US 61 bridge in Hastings, the I-90 Dresbach Bridge between La Crosse (WI) and La Crescent (MN), and most recently the US 63 Eisenhower Bridge in Red Wing. Not to mention a number of other, much smaller bridges around the state.
The I-40 bridge is newer than the I-55 bridge, yet it still had a structural failure. The I-55 bridge now has WAY more traffic running across it. I wonder if the old bridge is now developing new cracks.
2 years later, we need to build third bridge, because existing 2 are closed due to repairs
@@kvakerbillduck9500 Well, they'd better start building that bridge right now.
Unless you are thinking of hiring the army to build a bridge...
On the other hand, older bridges tend to be built with much larger safety margins, because they did not have the technology to build reliable bridges with smaller margins.
@@captainchaos3667 The Memphis area could stand to have a bridge built about 20-30 mi south of downtown to get thru-traffic bypassed out of downtown. On a map I see I-69 running west from 269 and I-22 but dead ends short of the river. It should be extended over a new bridge into Arkansas, and should be tied into I-40 somewhere between Forest City and Midway Ark for a better direct routing of eastbound traffic. For instance, a trip from Little Rock to Birmingham AL currently has to run on I-40 east to just short of the river, bearing right at the split for the I-55 bridge, then once across the river a driver must take a cloverleaf exit to stay on 55 (a quirky routing). 55 there is a refurbished urban "expressway" with a low speed limit (45) for several miles. Once it crosses US65 it's more like an interstate, but to reach I-22, local roads i.e. TN route 175 have to be used to reach I-22. There's a lot of chances to make mistakes, and you're dealing with local traffic and plenty of stoplights and store entrances.
@@dtvjho
US78 is how u get on i22, they are currently fixing us78 into i240 to be less of a traffic jam
It’s actually 100% better than it was a few years ago
I69 is suppose to be us61/49 etc, I think it has signs that say future I69 through there
St. Louis and Kansas City are a hell of a lot worse, it’s surprising that the traffic isn’t very bad in Memphis compared to other nightmare places
While the mayor of Memphis is democrat, thankfully the state is majority republican with republican governor
These states ran by democrats are absolute nightmare with roads and bridges
I’m still trying to figure out why Pennsylvania is so destroyed with the second highest gas tax
""I'm thankful that they're (motorists) still around to be inconvenienced" - love that phrase; will remember it when I'm stuck in a traffic queue because of an accident in the future...
looked for this as well lol
I watched this video when it came out, and again today I live in the Memphis metro, and I was very surprised to see Practical Engineering cover this ,the toll this situation took on the city was quite large considering how many people from AR travel into Memphis for work, as well as truckers coming in for shipping routes. Great video
I don't understand engineering at all, however, your enthusiasm, knowledge and great ability to articulate the information keeps me coming back for more. Many thanks Grady
This non-engineer found the clear, simple, yet not oversimplified, account of many bridge construction and maintenance issues interesting and informative.
Yesss this comment, simple yet doesn't miss important parts
"How did the inspector miss that crack?" He never got near it, that's how. His job was to get into one of those cranes the video showed, to get within arms distance, and he refused to do so because he didn't trust the crane (reportedly). If you're only inspecting the bridge once every two years, in a 5 year span, that's only two inspections. The inspector that actually caught the crack on video was there to inspect the cables, not the bridge, and they were using drones. He's the one that called 911 on both sides of the bridge, and had to argue with the Memphis side to get them to shut their end down because the dispatcher didn't believe him. Ended up talking to the Chief of Police and told them Arkansas had already shut their end down, so people coming west on the bridge would have nowhere to go. There are procedures in place for almost everything, but humans still have to follow them for the procedures to work.
V
I doubt they had nowhere to go, wouldnt be safe leaving them out on the bridge or make them go back.
When you shut down a bridge, you stop traffic getting on. You don’t stop traffic getting off. They certainly didn’t force people to stop on the bridge.
Not completely true. The crane thing was just that he wouldn't extend the crane's arm as far as it would reach, because the entire thing would start tipping over and it was too dangerous.
There were ways to find the issue, such as with drones, but they were using an outdated, unsafe, and inadequate method.
Whether they used a crane or a drone to inspect the bridge, there is usally a team of engineers/inspectors conducting these inspections and reviewing written reports and video footage from the drones, you either fire them all or you fire no one, but I guess to save face the spineless executives had to point the finger at someone, instead of taking responsibility for not noticing the crack before it became a major structural failure.
I love your videos, you make it easy to understand, keep the videos coming. well done.
All content and zero fluff in each video. Subscribed ! Keep doing your great job
This crack is killing my job, having to reroute an entire fleet of tractor trailers. I appreciate the video showing more info than just the news headlines.
I've been crossing over on 49 to and from 69/269. I never liked going through Memphis anyway.
@@AccountInactive we are picking up Ford parts from Marion rails and bringing them back to KY, right now they are stuck taking the Parkway back, dont think about getting a flat, its a dead zone and you are gonna pay a lot of monies.
At least it didn’t kill you!
@@Sc1Z I work for a trucking company too and finding anyone to do work on a truck near that bridge is almost impossible…let alone all the other detour routes around it. Definitely doesn’t help with a national shortage of tires, parts, etc. This bridge effects so much more than people realize.
Thank your Republican government officials for neglecting the proper inspection and maintenance of vital infrastructure
"How did engineers know to act so quickly and decisively?"
Because from the instant they spotted the crack, they became criminally liable to any deaths and damage resulting from that crack... and all engineers know it.
It's because for a change of pace they weren't overruled by managers and or politicians.
@@OnionChoppingNinja Rather they decided to bypass the middle management and make the call.
I don't think they were criminality liable because they were inspecting the structure above the deck. They acted quickly because they were good engineers and it was the right thing to do. You should give them credit as credit is due.
Why? Because they bypassed the opinions of all of those people who are “Engineers by election” ie: politicians who think optics are more important than reality. Maintenance is boring, new projects are sexy and have ribbon cuttings where everybody gets a pat on the back in the media except the people… engineers and tradesmen… who actually did the hard work.
It's called engineering ethics. You'd be surprised by how many people lack good ethical practices. It's one thing to have knowledge on how to be ethical, but practicing it is a difficult thing to do if you work in an unethical workplace culture.
The explanations using the bricks and the steel arch were very helpful -- they made it understandable for this non-engineer in a way drawings could not have.
As a Memphian, I really appreciate this video! Thanks for shedding light on something that, for us, was a less than one minute blurb on the news!
The "if your inspection hinges on a single person, there's something wrong with your inspection process" was great. Sometimes engineers only think in terms of design and materials and not about how work is actually done (by actual humans).
We've got a spreadsheet and all the cells are checked off. The bridge passed inspection.
@@paulvarn4712 My father was an engineer that was responsible for making those check lists, and the procedures for testing and inspecting the parts the companies he worked for built. All of his work depended on the guy using his procedures correctly and ethically. people that ignore crap like that piss me off, I drove over that bridge A LOT with very heavy trucks, what worries me is they have proven they miss stuff like that on one bridge, now I have to drive across the much older, and smaller i55 bridge, how much did they miss on it? With all their engineers busy on the I44 bridge are they even keeping an eye on the larger amount of stress the older bridge is taking? Makes driving that route a bit of a pucker factor.
Early in my career (engineer, not structural but manufacturing), I was taught to assume that visual inspection would miss 50% of defects when analyzing the effectiveness of a quality control plan. That's excessively pessimistic but forces the QA strategy to never depend solely on VI at any critical decision point.
Reminds me of the famous incident with the two catwalks that were supposed to be on a single beam support, but because it was cheaper and easier, support for one catwalk was scewed into the other.
My guess is it was a manager responsible for inspections.
I really enjoy the real-life case study format you've been doing recently!
me too! so much of theory is cool and all, but its so hard to see how it all works in practice. I think this series is the thing we need to _bridge_ that gap
Fascinating as ever. Also, the best explanation of the difference between QA and QC I could find.
Grady, you are awesome! Thank you for explaining this incident with easy-to-understand language. You covered so much, too! Keep it up!
Wow! It’s really great that the inspectors immediately recognized the danger, and that immediate action was taken to prevent a possible disaster
A true Seal Team 6
Imagine being the one making the 911 call. "Hello, I'd like to close a bridge please."
@@R3BootYourMind the 911 call was released and that's pretty much how it went: watch?v=_uiebWzi1zc
Yeah, four years late.
But it does seem that other inspection teams missed or ignored the developing fracture. Possibly why the unnamed Inspector was sacked.
Generally stuff like this is only caught after the innocent victims are dead, happy to see this was caught before motorists or anybody on the water was killed.
Yes.
Yes XD
I think this really emphasizes how much we take for granted the society that we live in that we see videos like this only because someone such as Grady took the time to understand and investigate what could have happened.
yeah, whoever made the call to 911 needs a bonus check.
They probably fired to 911 caller
It blows my mind how they seen this previously and either missed it, or dismissed it. It's also remarkable that this down did not experience structural failure as a result. But as you said, fortunately everyone is still around and despite the inconveniences of the shut down, nobody was hurt or killed.
Kudos too, to the engineers that saw this and reacted in the quick and decisive manor.
This is great analysis and info. It reminds me that complex structures depend on all it's parts working together for continued success just like humans in a specific company.
"Fired one guy". Unless it was the CEO, some people are being protected.
I'm sure it's a huge CYA. Someone has got to go ..... eeny meany mino MO - you're it.
It kinds of seems like that doesn't it.
It’s a state ran department 🤦🏼
Was the unnamed person even fired? We don't know, we can't check.
@@TGNXAR FOIA
Far too often in accident investigations, we see the singularly reprimanded person take the blame for systemic issues that were well out of their control. It seems far more likely to me, given the history of these types of failures, that the inspector raised the issue, was told to ignore it, and budget was never made available to address the failing bridge. This is how people die, and to let one person take the fall for this would be to completely miss the lesson. Again.
Very well said. Even if (and it's a big if) the inspector in question did not follow procedure and/or was incompetent, there shouldn't be a single point of failure for something as critical as a bridge. Also, if the employee was not up to standard, why were they hired and put in a position of trust?
Totally agree. I'm guessing the engineer knew that and that's why he went straight to 911 and leaked it to the news. However, I'm sure he didn't make any friends at work for going that route. I wouldn't be surprised if he was fired for some unrelated BS reason.
We do not have the time or money do do it right the first time, but we do have time to do it over again. Then because it is an emergency we can get all the money we need.
@@MSimp2k6 I didn't hear anyone got punished for the Oroville Dam problem in California. How many hundreds of millions of dollars in repairs will it finally cost? California was quick to put out it's hand for Federal money for a major portion of the repairs. Seems there were no inspections all through the dry years.
@@richardkroll2269 They knew about Oroville for many years. The California legislature repeatedly stated they did not have the budget to make repairs and punted the issue. The final report managed to blame everyone but the State.
It all comes down to the same old thing :budget.
Lovely crystal clear explanation on this video.
Great job narrating this video. Nice to watch and have someone explain the details that is knowlegable about it and also smart enough to explain it in a manner that those of us with less knowledge in the field can understand exactly what the concerns are. Very well done! I will be sure to subscribe to your channel.
This is almost as egregious as the guy who disabled the emergency brakes on that Italian cable car!
AvE
@@TheRogueRockhound
Ah I see you are a man of culture as well.
@@comancheclub3449 Texas sized 10-4 on that one good buddy. You have a great day you glorious bastard
@@TheRogueRockhound no, AvE didn't disable the emergency brakes, he just talked about the incident :)
@@lukes1978 Bro...Do I really need to tell you that I know this? Grab some coffee brother
On the day they announced the firing of the inspector, many of us local residents immediately felt it was nothing more than using that person as a scapegoat. It made us disrespect and distrust ArDOT even more.
Don't be surprised if they fire the engineer who called 911. He bypassed his boss and efforts to cover this shit up. Brought shame to the whole department. Oh, he is definitely getting his ass fired by his corrupt department.
@@mikeshoults4155 the inspector that called 911 was working for a third party company so it's possible that he has some level of protection in a government inspector wouldn't have
I'm not an NDI guy but how in the heck do you miss that humungous crack?!? That's either incompetence, neglect or a combination of both. The guys that DID catch it and called 911 immediately are the heroes in this story. Great vids by the way. Your channel just came in my recommendations recently and I've subscribed.
This is not true. Before when it didn’t pass entirely through, it seems impossible, but when you have a single person going through all of the inspection data for thousands of locations on tens of bridges, they will eventually miss something. The issue is inspectors that are too few in number and not given enough resources to back them up.
You speak so clearly and have a wonderfully, put together vocabulary. Sophisticated yet Easy to understand and where not, you respoke using, in other words...
Very interesting content!
Thank You!!
09:50 Yes! This is the reason for things like the pre-surgery time out. Everybody in the room *stops* and listens to someone repeat what they are about to do and who they are doing it on. If a single person even suspects that something is off, they speak up. You don't want someone to get the wrong leg amputated because of one person who didn't get enough sleep. Similarly, I find it hard to believe that these inspections aren't reviewed and signed off by many people.
You just described why I hate assisting in surgeries. Always too much going on!
The argument that this crack could have been missed accidentally falls apart after you realize this crack has existed for at least 5 years. Obviously the guy wasn't doing his job. You don't just "accidentally" miss a crack that large for 5 years in a row.
Or maybe, it wasn't the same guy for all of those 5 years and those guys did dutyfully report the crack and were told "well done, we take it from here and rest assured we take this very seriously" and then the reports were filed in the special circular filing cabinet sitting next to an expensive desk....
@@Bird_Dog00 Yup. They knew about the crack. They just didn’t want to spend the money to repair it. Conservative states are extremely good at trying to fix problems after they happen so they can “save money” instead of trying to keep problems from happening in the first place. Human lives aren’t their concern.
That's Trump's US for you...
Ignorant to the point of self destruction... 😉
@@BassandoForte While I'm certainly no fan of the orange clown, this problem isn't one he created. It's been going on for decades.
@@Bird_Dog00 - It's voted Republican 9 times out of 12 elections - the last one being in 1996... 👍👍
This is the most informative video on any subject that I have ever see . Thank you so much for explaining so much and making it understandable. Hats off to you👌🥰😌
Great video. You comment about the need for the managerial/administrative process providing oversight and quality control is absolutely spot-on, and it applies to so many fields of expertise; all your comments precisely ring true for the field of medicine and pathological analysis, for example - which is my own field of study.
"Yeah, we need to shut down the bridge, now"
"OK, gonna need a good reason"
"Well you see, there's this one beam that if it's even cracked, the entire bridge could fail"
"Ah, you found a crack in it then?"
"It's two beams now"
Not really a crack any more. It's a split.
I would LOVE to hear that 911 tape...
@@dougdobbs I saw/heard it on Twitter when this first kicked off, sure it’s google-able!
It’s incredible because *the dispatcher totally fails to understand what they’re being told* and the poor engineer gets audibly more distressed each time he has to repeat himself.
steel beam mitosis
Sounds like a Benny Hill Skit don't it ?
This crack was there for years. Bad inspections are to blame.
Barstool inspections...
Pencil whipped the inspections.
Yep, Arkansas was responsible for one if not all of them, and evidently at least one guy who did it just didn't give a shit about doing a good job that day. There may be earlier drone footage that may implicate more inspectors.
Tick the box inspection
Yeah kinda like Miami!!! Can't prevent a disaster if inspectors aren't giving a shit about their work. That's the problem with goverment employees. They're just there to collect a pay check
*Thank you--I had no idea.* *I've been across that bridge many times, the last time in April of 2021, I wondered what the problem was when I came back in August 2021, and had to detour.*
Great explanation of defect. You presented the failure in a very fair, objective way. It is scary to realize this bridge, which I have passed over many times as an Arkansan, may be an omen for other bridge failures across the country as our critical infrastructure ages. Thanks for your great educational videos. You should teach engineering!
"We know human are capable of mistake so we build processes that reduce their probabilities and consequences." In my opinion one of the most under-rated engineering design principles. We are only human. Your system must account for that. Whether it is civil, security, medicine, ... People fk up. Your system cannot hinge on a single person.
Excellent video. Glad they were able to shut down the bridge before it collapsed and there was loss of life.
Yea, but there is a HUGE difference between a mistake and willful negligence. The first inspection company I worked for had a fantastic owner. One day when I was new he pulled me aside and said, "If you are ever questioning if you should pass a part, close your eyes and picture yourself sitting on the witness stand, explaining to the judge and 12 jurors why you passed that part. If the thought of this scares you, it's probably best NOT to pass that part. (Wm. "Bill" Combs)" Words I have lived by for thirty years!
@@shawnjefferds9411 Err on the side of caution, always, for anything so critical. Sounds like aviation.
No job can be done properly unless there is sufficient manpower and training.
That includes the manpower and training to recognize when something has been
overlooked or not yet done. And I agree with you: this is true of all kinds of work.
@@rockym2931 manpower and training is impossible without funding, somehow we can afford trillions to protect the wealthy's wealth but virtually nothing for obviously needed infrastructure.
Tell that to old people. They love building shit that hinges on one person. And trying to find one person to blame
Similar scale of potential failure was identified on the Kingston Bridge in Glasgow 20 years ago causing a massive repair to address failing concrete.
Sorry, closer to 30 years, in 1990
Very interesting and educational video! You're so good at giving the details that most people can understand...I appreciate that! Thank you for creating, uploading and sharing!!😊🌉
Thanks Grady , I appreciate you!
The day the bridge was closed I made a comment in reddit that the rust of the crack looked old and got my rear chewed by others. In the end I was right. Thanks man.
Supposedly the crack was obvious 5 years ago.
As an engineer, I can't imagine calling 911 to have a bridge and a river closed ASAP. I'd love to hear a recording of that phone call!
@@Hooper-DrivesTheBoat Legit calls, or some drunk wasting your time? Assuming you can share it, what's a common example?
@@Hooper-DrivesTheBoat Interesting! How would you react if I called 911 to tell you to close down a bridge?
a BRIDE??? is closed? that wud be BAAAAD FOR THE GROOM... ?
wreg.com/news/frantic-911-calls-from-i-40-bridge-inspectors-reveal-seriousness-of-situation/
There are recordings to both state's 911 dispatch in that link. I think I would have snapped at the dispatcher from the Tennessee call.
@@tadferd4340 Thanks for the link. That was some pretty bad cell reception on the Tennessee call.
Thanks for the clear explanation, as always, Grady. I’d love to see a video on continuous sensing technology (fibre optic reflectometry, piezo, LiDAR, radar, GNSS) as applied to instrumentation of such critical structures for failure detection and prediction.
As you point out, periodic inspection by humans may not be sufficient to pick up all modes of failure
Sir, I enjoy your channel so much keep up the good work
I absolutely love this new trend of incident summaries, it made me finally join as a paying subscriber after years of enjoying your content. I absolutely love the "it's more complicated than that" and "you shouldn't rely on a single person" angle as well. As a former civil engineering student I've always tried to teach my colleagues in IT operations about stepping up their incident management, I'm always glad to have some layman examples on hand from fields that have been done this for a longer time :)
There is a slight mischaracterization about cracks initiating at or near welds. It is most common for a crack to initiate adjacent to the weld metal, in a high residual stress area known as the heat affected zone. Any sharp defects in this area, such as weld undercut, provide easy initiation sites for cracks as the residual stresses can approach yield level.
so ... pretty much what he said in the video?
@@chrishayes8197 sort of, that's why I said slight mischaracterization. He seems to imply through the graphics and the defects he is speaking about that something like a weld impurity or void might cause this issue, and that it would originate in the weld metal. But these types of inclusions are likely to lead to other failure modes like accelerated corrosion, not crack propagation. Cracks will typically initiate at the toe of the weld, or very near in the HAZ of the base metal.
Well stated with a good response to Chris Hayes. As an engineer with 50 years of experience I was thinking the same thing as Grady covered that potential mode of failure.
@@joshgeorge7 He pretty specifically said that the weld shrinks causing stresses on the rest of the material around it, ie the high residual stress area you mention. That was pretty clear to me that he didn't say the weld itself formed cracks, but that the shrinking caused cracks on the material right outside the weld.
The backer rod used on the inside of the boxes often are tacked causing another stress riser known as a fatigue prone detail. Thats my guess
I can see why you have 2.4M subscribers.
You describe the situation very well with no fluff.
These practical examples are an absolute gem