Hernando de Soto Bridge (I-40 Mephis) 19

[human909]

Some pretty serious looking issues here.

https://www.wmcactionnews5.com/2021/05/11/emergency-roadwork-shutdowns-i-bridge/

 

[IRstuff]

This image shows it better; the top plate of the beam is separated from the inboard vertical plate.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[Burloak]

Here is another photo linked above by @azcats :

https://www.ardot.gov/wp-content/up...ne2019_michaelbakerintl_hernando-1024x569.jpg

I assume this is the same location, so it appears that the cracking started at the bottom, outer corner. (the current photos show that the bottom plate is not yet fractured).
I can't believe they would leave a crack at least 80% of the web height, without even trying to drill out the crack tip to prevent it from progressing.

 

[azcats]

This is from this video which was made in 2019.

Bridge inspector also fired this morning.

[URL unfurl="true"]https://www.youtube.com/watch?v=qmbeDO53TK8[/url]

 

[davefitz]

per Wiki, the bridge was constructed in the period 1967-1972, prior to trade with the PRC, so that issue is not applicable. It may yet be a metallurgivcal issue, so let the metallurgical experts figure it out.

During that time period, some CS components fabricated in Spain had metallurgical issues, so it might be useful to review the QC documents , at least regarding the source of the steel.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[FacEngrPE]

Some of the information starts to make sense - the picture from above (IRstuff) indicates that the shape of the crack has turned the beam (Really stiff in tension) to a sort of spring (still stiff but much softer than the opposite side, which is uncracked), This could explain the asymmetrical behavior reported by TheGreenLama.

 

[1503-44]

Incredible video. They certainly like flying their drone.

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[Sparweb]

and...

 

[1503-44]

Well ... they're more interested in the paint on the gusset plate.

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[Alistair_Heaton]

Funny harmonic and unsymmetrical normal road loads?

Ie there are lorry's full always going in one direction and then empty going in the other direction?

 

[hokie66]

No lorries on this bridge, but lots of trucks. Most of them would be loaded.

 

[FacEngrPE]

An example of the common language which divides us.

https://www.merriam-webster.com/dictionary/lorries[/URL]]
lorry noun
lor·​ry | \ ˈlȯr-ē
, ˈlär- plural lorries
Definition of lorry

chiefly British
: motortruck

Also in the new image is the bolted cover for the access hole. They likely has some very small workers on the crew to use an access hole in this location. I would think stress would be higher at the access hole, then the crack location.

 

[LittleInch]

You can only think that someone thought that crack was just some sort of surface mark unless they were only watching it live on the little screen the inspector is using. You just wouldn't see it on that.

That pole sparweb pointed to isn't structural, it's a drain pipe from the roadway, but has been hit by something.

Were the vertical cross spars added later?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[GC_Hopi]

A few thoughts on the photo. Repairs are going to be extensive.

 

[Canuck65]

The vertical 'pipe' that appears on the right in the photo above is likely just a drain pipe extension, i.e. non-structural.

 

[JohnCE920]

I can't help coming back to just being thankful that this bridge had enough internal redundancy to prevent a collapse. This bridge was labeled by the DOTs as Fracture Critical and that tie is likely the main reason for the designation. And this FCM has had an enormous fracture for the last few years.... Just thankful no one ended up getting hurt or killed by this.

And that inspection drone video is hard to watch. I know we're all looking for the crack while the inspector is looking at the hangar... but wow. Its such a large crack even then. How do you miss that?

 

[LittleInch]

Perhaps they just thought it couldn't be a crack, but some oil or bird sh1t or something like that.

As said we don't know if they looked at it ever again on a big screen or just that little 9 inch hand held thing in the bright day light.

This time the crack was visible to the naked eye looking down from the deck so a lot more visible.

But there do appear to be more visible cracks in the tie so I wonder if they are now doing a rather more thorough inspection while the bridge is closed...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

HUA looking through a dirty navel lens.

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[microwizard]

I am glad we are speculating about how the inspector missed an obvious clue, rather than discussing how a major bridge collapsed in operation!

Possibly the "gorilla" problem? While fixated on one topic, the brain ignores others. But I would have thought an inspector would be proactively looking at every detail, certainly I often find faults while looking for something unrelated. I would be at least tempted to fly the drone in for a closer look, if not break out the climbing gear. I guess their employer felt the same.

 

[Craig Neth]

> How do you miss that?

Yeah.

To be fair, according to ARDOT, that drone video came from the contractor (Michael Baker) who was only hired to inspect the arch and cables, and that snippet was apparently part of a 5 hour long video that included a similar video of every other cable. I certainly wouldn't expect the operator staring at a tiny screen in broad daylight to find features like that, I assume it's all meant to be reviewed later.

I'm not at all familiar with how these inspections work, but perhaps the drone video is 'backup material' used when you have some question about a more primary type of inspection? Drones being a 'new technology', I could well imagine it is not considered a primary source for such processes.

ARDOT themselves inspected the bridge 6 and 18 months later, supposedly focusing only on these fracture critical elements, and didn't see it. So two different teams, on three separate occasions, all missed it. Lots of 'opportunity' for process improvement, it would seem.

This is all in the press conference video:

https://www.youtube.com/watch?v=rAtuWNDttvk

 

[JohnCE920]

Craig Neth,

If that drone is a team that specifically looking at the hangar / arch system. Sure I can see not getting that. But the fracture critical member of the structure would have been looked at closely. My experience in working with bridge inspectors doesn't cover a structure like this but I would assume a snooper truck being used to check under the bridge and get the inspector about arms length away from this.

I do agree that there is a lot of room for improvement here. And knowing the inspector was let go, its likely a person that didn't follow the inspection process. Its just a scary thought to think this crack was present for over 2yrs.