# I-85 fire: Section of Atlanta highway collapses



## knight1fox3 (Mar 31, 2017)

http://www.cnn.com/2017/03/30/us/atlanta-i-85-fire/index.html


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## canadagoose (Mar 31, 2017)

Aren't highways in the US mostly concrete?  How does that burn?


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## NJmike PE (Mar 31, 2017)

Hmm, steel structure collapsed from only a fire load.....







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## Road Guy (Mar 31, 2017)

the one good thing about a fire is that they will be able to trace what started it within a few days. My ATL friends are already pointing to some conspiracy theory about some old rolls of conduit stored under the bridge from a project that went south a few years ago as the "fuel".. But I would think you would need some major accelerate (gasoline, etc) to get a bridge to burn.. but yes anything can burn..

Traffic is going to be so fucked....


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## roadwreck (Mar 31, 2017)

This is the image that is being circulated that is prompting the "rolls of conduit" theory.  The conduit wouldn't just spontaneously combust so there had to be something else that sparked the fire.  My guess would be urban outdoors-men...

GDOT stores a lot of crap under this bridge.  I know they park HERO (Highway Emergency Response Vehicles) under another portion of the bridge.  When the fire was initially reported I assumed it was those burning.  I'm betting there will be a new directive from GDOT soon dictating that nothing should be stored or placed under bridges.


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## Road Guy (Mar 31, 2017)

that (storage) probably happens all around the country though.

So is that photo from before the fire "went crazy"?  I am not fire expert but it just doesn't seem to me that there is enough plastic there to generate enough heart to burn a concrete bridge?


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## NJmike PE (Mar 31, 2017)

Road Guy said:


> that (storage) probably happens all around the country though.
> 
> So is that photo from before the fire "went crazy"?  I am not fire expert but it just doesn't seem to me that there is enough plastic there to generate enough heart to burn a concrete bridge?


It all depends on how long the fire continued to grow. In it's "growth" stage, a fire doubles in size every 30 seconds. If it's inaccessible, then that would only add to the delay in supressing it


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## NJmike PE (Mar 31, 2017)

another thing to consider is what was in those "storage" containers. They clearly were not empty and I doubt it was plastic alone that generated that heat. Whatever the accelerant was, it burned hot enough and long enough to weaken the steel connections.


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## thekzieg (Mar 31, 2017)

I don't do road design, so I'm not sure about the typical assembly, but it looks to me like the fire melted the expansion joints causing the rebar to become exposed, the rebar then weakened and the whole section collapsed under its own weight. I don't think there's any other way to get such clean break lines on both sides of the collapsed span without it being an expansion joint failure.


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## Road Guy (Mar 31, 2017)

its just rolls of conduit, no containers that I could see (google street view)


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## Road Guy (Mar 31, 2017)

the bridge beams usually sit on the bridge "cap" (abutment) usually there is a foot or so of the concrete beam that rests on the cap, which supports the load. It would have had to burn hot enough to melt that overhand enough to allow it all to break clean.. from the pics I saw on news it looks like the "caps" are still intact somewhat

not sure how old this google street view pic is but there is a lot of conduit, maybe that would be enough. but you have to think it would have taken some serious flame to get that going..


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## NJmike PE (Mar 31, 2017)

The report should be interesting. Definitely going to be some finger pointing involved

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## Ship Wreck PE (Mar 31, 2017)

Did RG design that road?


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## TNSparky (Mar 31, 2017)

Road Guy said:


> the bridge beams usually sit on the bridge "cap" (abutment) usually there is a foot or so of the concrete beam that rests on the cap, which supports the load. It would have had to burn hot enough to melt that overhand enough to allow it all to break clean.. from the pics I saw on news it looks like the "caps" are still intact somewhat
> 
> not sure how old this google street view pic is but there is a lot of conduit, maybe that would be enough. but you have to think it would have taken some serious flame to get that going..
> 
> View attachment 9284


Holy cow! That street view pic is from November! I doubt they had moved any of that material since then (assuming that's the portion that collapsed). I didn't realize conduit could burn that hot. Guess I learn something new every day.


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## Road Guy (Mar 31, 2017)

Ship Wreck PE said:


> Did RG design that road?


lol - I did some design on I-85 further north and way further south back in the day, but that's not my viaduct!


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## Road Guy (Mar 31, 2017)

this pic shows the cap is still mostly "there"  check out the column (can barely see at the bottom) looks like another section of the bridge each side will also have to go.


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## NJmike PE (Mar 31, 2017)

damn, so the girders failed..... all together?


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## csb (Mar 31, 2017)

I'm glad they are tied off and wearing hard hats.


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## thekzieg (Mar 31, 2017)

Safety first. Always.


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## EB NCEES REP (Mar 31, 2017)

those look like surveyors who are not smart enough to listen

I think this will work until they get it fixed - just change direction for AM / PM Rush Hour


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## Voomie (Mar 31, 2017)

csb said:


> I'm glad they are tied off and wearing hard hats.


Shhh OHSA doesn't need to know.

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## MA_PE (Mar 31, 2017)

Hard hats?  In case things fall from the sky?  Tied off is probably not a bad idea, though


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## csb (Mar 31, 2017)

MA_PE said:


> Hard hats?  In case things fall from the sky?  Tied off is probably not a bad idea, though


Our agency is a hard hats on in the field, all the time, no questions asked. It stems from an OSHA fine a few years back.


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## Voomie (Mar 31, 2017)

Hard hats always on the jobsite. I know it looks silly in this case but we had a few of our go home alive because they were wearing hats. You don't want to deal with a complaint to OSHA.

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## Voomie (Mar 31, 2017)

Should be ready by Monday.






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## Road Guy (Mar 31, 2017)

It's always easy to spot the people that don't know anything about construction, they are usually the ones talking about hardhats


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## csb (Mar 31, 2017)

Hey, I don't make the rules. I just abide by the rules made by people whose job is to make the rules. 

Lack of hard hat here is grounds for dismissal. It was a pretty big OSHA fine.


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## Voomie (Mar 31, 2017)

csb said:


> Hey, I don't make the rules. I just abide by the rules made by people whose job is to make the rules. Lack of hard hat here is grounds for dismissal. It was a pretty big OSHA fine.


They normally are. If you have a fatality they investigate every so thoroughly that they know what you had for lunch last Thursday.

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## Road Guy (Mar 31, 2017)

The people in the pic are state employees so what do you expect?


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## roadwreck (Apr 17, 2017)

And now a different Atlanta interstate has exploded.

http://www.cnn.com/2017/04/17/us/atlanta-i-20-road-damage-trnd/index.html


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## Road Guy (Apr 17, 2017)

F'n utilities!


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## knight1fox3 (Apr 17, 2017)

Road Guy said:


> F'n utilities!


Haha...dammit @mudpuppy!


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## Road Guy (Apr 20, 2017)

just when you didn't think traffic could get any worse in Atlanta!


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