So once the crack was discovered last month, how did the process go for getting the bridge closed? An inspector discovered the crack, and then someone with mediocre communication skills placed this 911 call, and…then what? Presumably the state police didn’t simply take their word for it and shut down traffic as soon as they rolled up. Could the crack be seen from someone standing on the edge of the roadway? Would one state trooper, having seen the crack, have the authority to make the shutdown decision (at least for his end of the bridge)?
The bridge inspector said he talked to ARDOT before calling 911.
The official at the first ARDOT press conference indicated they called their counterparts at TDOT. They didn’t give specific details.
I assume 911 just sent patrol cops to the bridge. It probably took some coordinating with TDOT to actually close that bridge during rush hour.
I think calling 911 was an illustration of government incompetence: departments of transportation should have direct high level connections to law enforcement rather than going through the 911 system which is for the general public.
The Arkansas department also has broadened its internal investigation into the program to include an unauthenticated photograph from 2016 that appeared to show a crack developing in the area where the significant fracture was found, Tudor said.
The department has asked the inspector general’s office to authenticate the photograph, but agency officials now assume that the photograph is accurate and the fracture dates back as far as 2016.
I wonder if this means that there is a scramble to start inspecting all the other bridges overseen by ADT.
How much is bridge inspection automated these days? For example, it seems like drones could be equipped with high tech cameras and sensors to autoscan all surfaces of the bridge and then computer AI analyzes the results to identify any potential problems.
TDot posted two updates with photos. They pretty large with clear details.
The contractors are working long hours and getting a lot done. People should appreciate the effort to get this bridge open.
Very large Jack’s installed. One photo shows the tie rod and they’re lowering the jack to attach.
Brackets and tie rods
Brackets/weldments geez, the size.
Sounds painful. 
I wish they’d post more than 10 sec vids. That may be a Twitter requirement.
I’m beginning to think they’ll finish repairs ahead of schedule.
After that disastrous building collapse in Miami this morning, that this was caught in time is even more important than we may have realized.
Yes. If you look at @PastTense animation you can see a phase 2 where they are installing post-tensioning rods. Those rods are used to apply tension to the system to return it to it’s originally intended tensioned state before they weld in the final patches. This need for tensioning is why this is a long, multi-step process and not just a simple patch over the break.
I don’t think that’s why. I think they are removing the floor beams because they all attach at the points where the patches need to be welded on. They need to make way for the new steel.
It think the video posted above suggests that the earthquake remediation steps they took might have been the culprit. They apparently attached the roadway to the tension members which is a fundamental change in design. This could cause the steel to cycle through stress and strain cycles that are way out of spec. We won’t know for sure, but that’s where I’d put my money.
Everyone is relieved this bridge didn’t suffer a catastrophic failure. Hopefully it’ll be stronger and last another 50 years.
TDOT reports the new steel is being installed.
Short video here…
Glad they throughly tested the welds. I remember XRays were used to test deep welds on steel. Is ultrasonic now the standard test? It requires special certification to deep weld structural steel. https://www.arkansasonline.com/news/2021/jul/07/update-given-on-i-40-bridge-effort/
UT and Xray are both still used The process used depends on the application, and sometimes the joint configuration.
It’s not a special certification to deep weld (or full-penetration weld, as it’s known in the industry) structural steel - we have welders in our small shop certified to AWS D1.1 for unlimited thickness on steel, in all positions (flat, horizontal, vertical, overhead). Bridge work requires certification to AWS D1.5 (AWS being American Welding Society). They are common enough certifications in both instances, and most all structural steel jobs require certified welders, whether buildings, bridges, or whatnot. There are also separate certifications for welding sheet metal, rebar, aluminum, stainless, & the more exotic metals (though not all fall under AWS).
Thank you for the info on welding.
The original crack repair is complete. 
TDOT painted the new steel this weekend.
They still have to reinforce the bad welds that were identified. My local news reported they’re hoping to reopen the bridge by the end of July. Maybe early August.
I’m impressed that repairs went so quickly. Back in May it seemed like it might be Sept before they could fix the bridge. It could open tomorrow but they’re being extra cautious in reinforcing the weak welds. What happened in Miami must weigh heavily on TDOTs decisions.
This is copied from the July 6 and 9 updates (docx file)
https://www.tn.gov/tdot/projects/region-4/i-40-hernando-desoto-bridge/library.html
July 6
July 9
I haven’t followed it that closely, but it seems like the earthquake retrofit seems like it probably contributed to the crackd and failures by changing the loading patterns. Have they dug into the root cause? Do they know if other bridges were badly modified in a similar way?
I’ve seen a lot of discussion about a bad weld failing at the crack. It caused enough concern that TDOT did ultrasonic testing of more than 500 weld connections on the bridge. Nine welds are being reinforced with steel plate before reopening the bridge.
I hope a final analysis of the structural fault is eventually published. The I40 bridge failed a few years after the seismic retrofit. That raises a lot of concern about the older I55 Bridge that had similar work done. The engineers need to come to some definitive answer.
That bridge is lucky to be standing.
From TDOT’s July 12 briefing doc. Notice they say critical repair. https://www.tn.gov/tdot/projects/region-4/i-40-hernando-desoto-bridge/library.html
It’s ironic that the bridge was fixed for earthquakes.
Thanks for the updates. This is good to know, especially because things could have ended up VERY differently.