# I-40 Bridge (into Memphis) closed for emergency inspection \[update - bridge has been re-opened\] **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [May 12, 2021, 11:39am UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897 "2021-05-12T11:39:44Z")\ **Posts on this page:** 20\ **Page:** 5
**Author:** ![abcdefghij](https://avatars.discourse-cdn.com/v4/letter/a/43a26b/32.png) [@abcdefghij](https://boards.straightdope.com/u/abcdefghij)\ **Post date:** [May 14, 2021, 2:55pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/82 "2021-05-14T14:55:55Z")
She left it out because it actually _is_ ironic ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [May 14, 2021, 2:58pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/83 "2021-05-14T14:58:14Z")
So _her leaving it out_ is also ironic. Hence the song _is_ in fact ironic, not because any of the examples in the song are ironic, but because she ironically left out the duct tape irony. You see, Alanis was just operating on a different level. ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [May 14, 2021, 2:59pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/84 "2021-05-14T14:59:27Z")
> [@abcdefghij](#): > > The bridge is not safe to even stand there on its own without inspection for other damage and finite element analysis of the remaining structure. Yes. The fact that the bridge is still standing despite a complete break of one of its main beams is a testament to how good the overall design is. Until they know exactly what’s going on, it is completely unsafe to be on or under the bridge. I wonder if the earthquake retrofit changed the stresses in an unexpected way. The break looks like an odd failure mode to me, but I’m no structural engineer. Half joking: the inspector should have called in a bomb threat. You see a failure like that and pray you can get off the bridge in time. ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [May 14, 2021, 3:03pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/85 "2021-05-14T15:03:57Z")
> [@Crankyhillbilly](#): > > This bridge opened in 1973 making it a youngster at 48. There is nothing particularly unusual or untoward about a bridge with a designed lifespan of 50 years having a major structural failure at 48 years (and that’s ignoring the fact that construction actually began on the bridge five years earlier. Bridge components don’t magically stop aging just because the bridge isn’t finished yet). > [@Crankyhillbilly](#): > > Bridges should last a 100+ years with just maintenance and deck replacement. Says who? You? What do you know about it? According to the [American Society of Civil Engineers](https://infrastructurereportcard.org/cat-item/bridges/), the required designed service life of even today’s bridges, with all the modern design and construction improvements available to us now, is 75 years: > [@](#): > > […] the industry manual provided by the American Association of State Highway and Transportation Officials now requires new bridges to be designed with a 75-year service life, compared to the customary 50 years, meaning bridges are now being built to last longer. > [@Crankyhillbilly](#): > > There are wooden bridges that have lasted 100 years, umpteen million dollar steel bridges should at least last that long. Oh, please do communicate that insight to the American Society of Civil Engineers and the American Association of State Highway and Transportation Officials. Why, I expect it’s never even occurred to them that some small wooden bridges outlast some massive river-spanning modern steel bridges carrying major highway traffic, and they’ll be very grateful to you for pointing that out to them. And then please get back to us and let us know how fulsomely they thanked you for your brilliant observation. > [@Crankyhillbilly](#): > > The 250 million plus ones we are building now sure as hell better or my progeny should hang the people who built thems progeny. If your progeny don’t know any more about civil engineering than you do, I expect they’ll try. Hopefully there will still be some better-informed and more law-abiding people around to stop their attempted murderous expression of their ignorant resentment. ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [May 14, 2021, 4:04pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/86 "2021-05-14T16:04:31Z")
The Coast Guard has reopened river traffic under the bridge. > **[Waterway under vital Memphis bridge reopens to maritime traffic - KTVZ](https://ktvz.com/news/national-world/2021/05/14/waterway-under-vital-memphis-bridge-reopens-to-maritime-traffic/)** > > The US Coast Guard said Friday that transit on the Mississippi River waterway under Interstate 40 bridge in Memphis has reopened after a crack forced the closure of the vital highway bridge. Earlier Friday, the Coast Guard said more than 60 vessels... ---
**Author:** ![abcdefghij](https://avatars.discourse-cdn.com/v4/letter/a/43a26b/32.png) [@abcdefghij](https://boards.straightdope.com/u/abcdefghij)\ **Post date:** [May 14, 2021, 4:05pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/87 "2021-05-14T16:05:16Z")
> [@Pleonast](#): > > I wonder if the earthquake retrofit changed the stresses in an unexpected way. The break looks like an odd failure mode to me, but I’m no structural engineer. I wondered the same thing. I’m a materials scientist and a former colleague was involved in the Silver Bridge metallurgical analysis, but I claim no deeper insight than that. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [May 14, 2021, 4:14pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/88 "2021-05-14T16:14:43Z")
It’s a tied-arch bridge, meaning that vertical loads pulling down on the arches try to flatten the arches out, but that the chord (road deck) acts in tension to keep the whole thing together, kind of how a bowstring keeps a bow bent. Cracks in the road deck like that threaten the entire shebang as a result. If it wasn’t a tied arch design, the arch-flattening would be counteracted by something else, and the failure there wouldn’t be nearly so structurally significant. ---
**Author:** ![PastTense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pasttense/32/14550_2.png) [@PastTense](https://boards.straightdope.com/u/PastTense)\ **Post date:** [May 14, 2021, 4:43pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/89 "2021-05-14T16:43:24Z")
> [@Pleonast](#): > > Until they know exactly what’s going on, it is completely unsafe to be on or under the bridge. Then here are a couple idiots (who are also bridge inspectors?): [![](https://wreg.com/wp-content/uploads/sites/18/2021/05/I-40-bridge-inspectors.jpg) ](https://wreg.com/wp-content/uploads/sites/18/2021/05/I-40-bridge-inspectors.jpg) [The crack is between the legs of the bottom person.] ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 14, 2021, 4:45pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/90 "2021-05-14T16:45:26Z")
> [@Crankyhillbilly](#): > > Not for the bill but for their project specifically. They want to make sure it gets funded. 2 trillion sounds like a lot but when you see the price tag for these bridges it isn’t. One St Louis project had a price tag of 695 million. You think a bridge with a major structural beam that’s literally broken in two and shifted a couple of inches would _ever_ get denied the funding needed for an emergency repair? I guess they’re passionate about securing the funding for bridge repair because they’re concerned about public safety, which I guess would be the reason, in this scenario of yours, that they knew about the damage long ago but chose to compromise public safety for some time before drawing major attention to it? ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [May 14, 2021, 5:08pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/91 "2021-05-14T17:08:21Z")
> [@abcdefghij](#): > > The load carried by the now-broken span has now been transferred to other elements of the bridge, possibly exceeding their design allowances. Someone on local news (Little Rock) mentioned that the bridge has a “factor of safety”. If a bridge expected to carry 100 tons is designed to hold 200 tons, that is a factor of safety of 2. Does anyone know what the FOS for a freeway bridge is, typically? ---
**Author:** ![carrps](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carrps/32/2957_2.png) [@carrps](https://boards.straightdope.com/u/carrps)\ **Post date:** [May 14, 2021, 5:14pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/92 "2021-05-14T17:14:16Z")
Apropos of nothing I guess, but I’d seen a program about the collapse of the Silver Bridge (pretty sure it was _Nova_), so when my BiL insisted I watch the _Mothman_ movie, I was telling him that the bridge was going to collapse at the end. Spoiled the suspense a bit. ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [May 14, 2021, 5:33pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/93 "2021-05-14T17:33:25Z")
> [@Machine\_Elf](#): > > I guess they’re passionate about securing the funding for bridge repair because they’re concerned about public safety, which I guess would be the reason, in this scenario of yours, that they knew about the damage long ago but chose to compromise public safety for some time before drawing major attention to it? Don’t try to guess the motivations of Big Bridge. They’re operating on an entirely different level from the rest of us. ---
**Author:** ![FloatyGimpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/floatygimpy/32/7750_2.png) [@FloatyGimpy](https://boards.straightdope.com/u/FloatyGimpy)\ **Post date:** [May 14, 2021, 5:35pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/94 "2021-05-14T17:35:06Z")
His “safety harness” is attached to the broken part! 😬 ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [May 14, 2021, 5:38pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/95 "2021-05-14T17:38:36Z")
> [@PastTense](#): > > [The crack is between the legs of the bottom person.] He’s going to pee on it and make it all better. 😃 ---
**Author:** ![abcdefghij](https://avatars.discourse-cdn.com/v4/letter/a/43a26b/32.png) [@abcdefghij](https://boards.straightdope.com/u/abcdefghij)\ **Post date:** [May 14, 2021, 5:40pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/96 "2021-05-14T17:40:10Z")
> [@TroutMan](#): > > Don’t try to guess the motivations of Big Bridge. They’re operating on an entirely different level from the rest of us. You forgot to say “Sheeple!!!” ---
**Author:** ![abcdefghij](https://avatars.discourse-cdn.com/v4/letter/a/43a26b/32.png) [@abcdefghij](https://boards.straightdope.com/u/abcdefghij)\ **Post date:** [May 14, 2021, 5:43pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/97 "2021-05-14T17:43:39Z")
> [@aceplace57](#): > > He’s going to pee on it and make it all better. I don’t believe that bridge steel is rated for urine. ---
**Author:** ![silenus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/silenus/32/166_2.png) [@silenus](https://boards.straightdope.com/u/silenus)\ **Post date:** [May 14, 2021, 5:52pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/98 "2021-05-14T17:52:34Z")
Hell, that’s why the bridge broke! Superman was peeing off of it and lost control of his urine stream, fracturing the steel. ---
**Author:** ![abcdefghij](https://avatars.discourse-cdn.com/v4/letter/a/43a26b/32.png) [@abcdefghij](https://boards.straightdope.com/u/abcdefghij)\ **Post date:** [May 14, 2021, 6:07pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/99 "2021-05-14T18:07:44Z")
> [@carnivorousplant](#): > > If a bridge expected to carry 100 tons is designed to hold 200 tons, that is a factor of safety of 2. Does anyone know what the FOS for a freeway bridge is, typically? I don’t know. I do recall that inadequate factor of safety (I vaguely recall a localized FOS of only 1!?) was identified as one of the root causes of the Silver Bridge collapse. The Silver Bridge collapsed in late 1967. A [year later](https://web.archive.org/web/20111015132329/http://museum.nist.gov/exhibits/silverbridge/eyebar.htm) DOT instituted more stringent bridge inspections and likely tightened the requirements on engineering allowances. Construction on the I-40 bridge was already well underway by then. What are the odds that they were required to go back and redo it? The FOS required today, or even in 1969, would not have been what was required when the design of the I-40 bridge was approved. Note, I am not saying that the FOS _of the remaining bridge_, much less the designed bridge, is inadequate. I’m saying that it’s unknown until the plans are compared to the actual structure and the analysis is done. ---
**Author:** ![k9bfriender](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/k9bfriender/32/3283_2.png) [@k9bfriender](https://boards.straightdope.com/u/k9bfriender)\ **Post date:** [May 14, 2021, 6:14pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/100 "2021-05-14T18:14:10Z")
> [@Crankyhillbilly](#): > > 2 trillion sounds like a lot but when you see the price tag for these bridges it isn’t. One St Louis project had a price tag of 695 million. I mean, it still is. You know what you have left over in 2 trillion after spending 695 million? About 2 trillion. ---
**Author:** ![slash2k](https://avatars.discourse-cdn.com/v4/letter/s/439d5e/32.png) [@slash2k](https://boards.straightdope.com/u/slash2k)\ **Post date:** [May 14, 2021, 6:21pm UTC](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897/101 "2021-05-14T18:21:56Z")
> [@carnivorousplant](#): > > Someone on local news (Little Rock) mentioned that the bridge has a “factor of safety”. If a bridge expected to carry 100 tons is designed to hold 200 tons, that is a factor of safety of 2. Does anyone know what the FOS for a freeway bridge is, typically? Current bridge design standards (based on AASHTO’s _LRFD Bridge Design Specifications_) use Load and Resistance Factor Design, a methodology that doesn’t reduce to a single number for factor of safety but uses a probabilistic approach. The target level of safety is a probability of member failure of less than 2 in 10,000. The LRFD approach is thought to be more realistic because the single “factor of safety” number hides a lot of uncertainty and overly simplifies matters; for example, the actual degree of loading on a bridge from wind and water and rain/snow/ice can only be approximated, traffic patterns change which changes the live load on the structure, etc. One of the things to keep in mind is that a broken member does not necessarily double the load on the adjacent member; stresses can be transferred in a multitude of different ways depending on design, so a number of adjacent parts may each acquire a slightly higher load, or lateral stresses cause a single part to shoulder multiple times the load. (Also, of course, until they finish the inspection they don’t know whether they’re dealing with a single broken support or a whole bunch of supports with varying degrees of compromise.) [Previous page](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897.md?page=4) [Next page](https://boards.straightdope.com/t/i-40-bridge-into-memphis-closed-for-emergency-inspection-update-bridge-has-been-re-opened/941897.md?page=6)