Cor ten steel needs multiple wet and dry cycles to form the protective layer to stop rusting. With a stream underneath and all the trees around it might have never stopped rusting. Also the pvc drain was not the original construction. The original drain probably rusted away and put water on the steel. The temperature was near 0 degrees that morning, if the expansion joints were not working the bridge could have contracted 3”

Fascinating! How shocking to learn that the cross-bracing was removed. Anyone who has ever built an IKEA bookcase knows that the cross bracing provided by the backing is what makes it stand up. Unbelievable. Very well done and straight to the point. Thank you!

I left Pittsburgh just a few months ago and lived right near that bridge. I drove over it with my family all the time, and walked under it almost every day as that is part of Frick Park. I always got a vague unsteady feeling walking under such a large bridge, but I thought authorities, engineers, etc knew what they were doing. As others have said, it's a miracle no one was killed.

City of Pittsburgh bridge maintenance policy: As bridges fall apart just remove broken pieces and pretend they never there. What can possibly go wrong?

What's sad is here in Pa. we have one of the highest taxes and the worst roads and bridges to drive on!

Cor-Ten steel, all the rage in the Seventies, forms an oxide coating that prevents further rusting. HOWEVER, when exposed to salt, the oxide coating is stripped away and the steel rusts like any other mild steel.

It's inconceivable how you can frequently attribute a bridge collapse to easily traceable factors, chiefly maintenance related. Something that was before the eyes of everyone: workers, inspectors even the people passing by probably for so long that even Google captured a bridge in a state it almost certainly wasn't built to stand. And yet it did... until it gave way.

I rode my bicycle across it a few years back to and from work in Oakland. The last time I biked across it was back in November 2021. I remember just a few months back, looking down from the top, It was difficult to see the bottom, It looked like a bottomless pit. It is a miracle there were no fatalities. These bridges definitely need more frequent inspection, especially those that are corroded and weak. Regardless of how often they are used. If they are not structurally safe, they need to be repaired or replaced. It is so unfortunate so often the all mighty $ speaks above peoples lives in this world

I can name at least five other bridges in Pittsburgh that you can see are structurally compromised by rusting steel or failing concrete

Amazing work on that animation. You folks did a hell of a lot of work

Live up the street from this bridge. I ran outside thinking there was a meteor strike from the sound of it.

Thanks gives a better look we cross this bridge everyday

I crossed this bridge every day growing up. My old man still does (I guess did). Really hard to believe no one was killed

It was announced today, February 7th, that infrastructure funds were diverted to “other areas” to the tune of billions in Pennsylvania

I live in pittsuburgh, and there is photographic evidence that the supports on the ground were rusted clean through and they put up banded cable cross braces to "supplement them."

This bridge collapse is criminal neglegence, plain and simple. Yet there have been zero investigative reports of who is responsible for putting the public in danger. Seems like local media could be in the back pocket of city or state... Thanks though for your well done explanation of how the bridge collapsed. Let's get to why the public was placed on this dangerous bridge what is clearly a long long time.

Folks as a structural engineer I can tell you that removing the cross bracing and replacing it with cables is a perfectly acceptable repair if done correctly. X-bracing members carry only tension forces, so replacing them with cables provides the same general structural behavior. It is possible that when the original bracing failed, load redistribution occurred which placed unintended lateral load on the columns, which induced bending stresses about their minor axes. If the new cables were not tensioned to pull the structure back into its original geometry, then these new stresses would have become permanent and could have contributed to the buckling of the columns.

The question has to be asked, if the bridge was inspected in September why were these issues not discovered, and if they were, why was this bridge not shut down?

I live a few blocks away from this bridge, just went over it the day before it collapsed. Scary shit. Anyways, amazing visualization on what probably happened.

I wouldn't say snapped out of place but simply rotted or rusted out as there was so little steel left holding it in in place. One can only wonder how many more death traps like this are out there.

It wasn't a lack of funding it was a lack of maintenance due to misappropriation of funds that caused this bridge to collapse.

In fairness this is pretty much every bridge in Pittsburgh and surrounding areas. I live 30 minutes away from Pittsburgh and the 2 main bridges here look like crap but theres no other way to travel without them so you just gotta go across

Thanks, this is very illuminating. I didn't know it was Cor-Ten steel, but the corrosion visible was extreme. Very nice graphics.

That bridge is three blocks from my house. Its incredible to think something like that is so real.

Would the cables that replaced the cross members change your animation?

You missed the fact that they added steel cable crossbraces after the original metal ones failed. Bridge still collapsed but you showed everything else, figured that would be in your video also.

The Emsworth Port Authority Bridge in Allegheny County started to fail and corrode badly several years after it was build many years ago. It too was CorTen steel. It was closed and had to be rebuild several years ago because of the on going bad corrosion issues that had gotten worse when /CorTen steel is exposed to road salt. It was bad. Any CorTen bridges should replaced immediately!

That cross brace was corroded right through, and this video did not show the cables that were added in place of the braces, which did not provide the same level of stability that the steel cross members offered. The cold temperatures could have further tightened those cables that could have pulled the legs right out from under the bridge.

Too bad that 7% of the infustructure bill actually goes to infustructure.

Bridges aren't even painted regularly there let alone repaired when needed. Politicians will tell you taxes need to be raised to fix the problem.

Wow I use that bridge often when in Pittsburgh my son is buried in cemetery on that same street ! So glad no one died or seriously injured 🌞

Amazing animation!!

Wow! So well explained

how much did that bus weigh? Was that the normal route for that size bus?

Why wasn't the lower x brace repaired or replaced?

Hi Mike! I am a Civil Engineering student at Lehigh University and am doing research on this bridge collapse. I was wondering if you could possibly supply me with this model and any other key information you may have?

Can you tell when the cross bracing was removed?

That bridge collapsing has made me late to school everyday lol, I live 3 blocks away and took it 2 times every day.

OMG that’s horrible. I have not even heard about this. Was it recently ? Was there a train ? (Assuming so) Any fatalities . The animation is fantastic by the way !! Dang that gave me shivers for obs reasons

Mike, any idea on why bridge collapses seem to be so frequent in the USA?

Great vid mike, ty

Maybe, some day, I'll find out where this was! The aerial pictures don't show me anything and I have no idea where Fern Hollow is.

This bridge collapse was completely avoidable. The state had started a gas tax to pay for infrastructure repair. They have so far collected $4.5 billion from the people. News broke a couple days ago that none of this money has been spent on infrastructure, rather it’s been spent on a host of other unrelated things.

At our power plant there are Clean Condensate Tanks to supply clean water to the boilers. There is a sample system with the water from the CST to a sample point used to test the water. There is a large filter in line on the sample line. The filter would clog up with fly ash and algae and the filter would need to be replaced. The instrument techs didn't like changing that filter so they removed the filter and the filter canister from the line. In their mind they fixed the problem. X brace rusts through and breaks so the solution is to just remove the whole X brace.

The cor ten from US Steel. Additional corrosion? Doubtful. Steel fatigue due to axle weights, more traffic than designed for. Fatigue cycles. Steel Failure in weld effected zone, brittle, There is a large triangular opening in the transverse beam. The upside down auto is to its left in photos. The top corner appears ragged. There is no steel framing for replacement of the hole as there is on the square hole to its left. Suggest compare to earlier current photos. Did somebody use a torch up there? Or some C4? Co-incidence that prez arrived a few hours later.

The bottom beam where it met the cement foundation looked completely rusted through. I used to live by a viaduct that crossed a busy street and whenever I passed underneath the viaduct I'd look up and see daylight through completely rusted out support beams and was horrified. I wondered how it was allowed to carry train traffic. Fortunately the viaduct was rebuilt and no tragedy occurred.

That bridge span is one foot longer than the number of bridges in Pgh.

Highest gas tax in the nation and still we have the worst bridges in the country

So....... What does this actually explain. I think it simply leads to more speculation. Yes the cross brace snapped, but it was removed and replaced with cabling. Did this have an effect on the structural integrity, or was it a valid repair? Amazing how many people seem to be bridge "experts" after something like this happens.

There wasn't a whole lot holding up that bridge to begin with, and there was very little cross bracing to give it rigidity. The solution to the corroded braces was to remove them? Where's the logic in that? Of course road salt would increase corrosion, and they should have planned for that.

Can we have an overview of why the pretensioned pedestrian bridge in Florida collapsed a few years ago? The media does its hysteria dance for a few weeks, then NIST l does its glacially paced thing for who knows how many years, then there's one or two more stores about lawsuits, then nobody except the families directly affected remember or care about it anymore and it's forgotten.

On 2/12/02 I witnessed the 165 ton steel truss collapse on the 13th cantilever at the new, David L. Lawrence convention center! One man killed, two injured!

This bridge collapse has RUINED my commute let me tell ya

It’s amazing! Why would anyone think that the remedy for a broken cross brace would be to remove it completely?🤪

Hello from the Burgh!

You didn't see the big rubber bands they put in place at a cost that couldn't even imagine.

The U.S. STEEL BUILDING HEADQUARTERS. In downtown Pittsburgh is made completely of core-10 steel also.

Who the F*CK signs off the inspection on these bridges?

That and the geological followup event, was the water main break in philly, a 48" main. These things happen every winter from Maine to ohio.

Salt is your problem. it destroys steel and concrete. It would be cheaper for all communities if winter tires were used instead of salt.

the salt water on the road runs down and the salt water mist created by car tires flinging the tiny droplets and making them airborne drifts and gets on everything in the area. When the salt water gets on the metal it starts to rust. on a hot summer day the water evaporates but the salt precipitates and stays on the rusty metal. The rust gets deep and starts to crack off like skin flakes comming off and the salt is trapped under the salt flakes. basically once the salt is on the metal it sticks to it like a salinated goo unless you pressure wash it numerous times. I know this because I own a salting truck and I see how pesky that salt is to remove. its harder to remove once the rust in on the metal because the rust creates cracks in the surface where the salt can hide. You can wash it a hundred times and there is always a spot that turns white after the water evaporates on a hot day.

I actually live in the Pittsburgh area.

Still surreal 🙏. Please keep the victims in our thoughts and or pray.

Great video! Our government rocks! They do such an outstanding job for us!!

It’s because pa does not give a fuck about our bridges I’ve painted a lot of them and there are so many failing in horrible shape but not fixed. Fix our infrastructure why pay taxes

America's infrastructure in a bridge, we are definitely headed on an upwards trajectory, stay the course!

used to hang under it. was in garbage condition. luckily its only utility was connecting the wealthiest part of pittsburgh to clay tennis courts and lawn bowling.

That was a very close call, could have been so much worse. I'm left wondering if the use of chemical de-icing agents had anything to do with the deterioration. We here support President Bidens infrastructure plans.

How many other bridges are in this state of disrepair ? How many bridges would have been repaired it the govt had not used $4billion from gas tax supposed to be used to repair roads and bridges, on other things?

Living in Pittsburgh since 2002 originally from Serbia, As kid watched bunch of Hollywood movies where everyone is super rich no one works big houses beautiful houses 😂 The first day in Pittsburgh was July 12, 2002... From airport straight to Squirrel Hill where we stayed at first and WE ALL FELT WE TIME TRAVELED 200 YEARS BACKWARDS !! RED AND BLACK DIRTY OLD BRICKS CHEAP HOUSES MADE OF WOOD roads are like 50+ years behind Europe,, potholes everywhere, nothing more funny than seeing a Warning road sign saying ROUGH ROAD 😂😂😂 entire PA has rough roads. Still 1700s bricks and stones and railroad tracks underneath just repaved with asphalt. And that Liberty Tunnel they have been repairing it since i moved here and now when you drive in it you feel the car is wobbly and that should be big concern since it feels like the ground has shifted a little but who cares they will fix the ventilation Fans that will take care of moisture and rust that's been building up in the last 100 years. So many bridges but for some reason they refused to connect Hazelwood Ave --- Becks Run Rd Or Forbes Ave with 2nd Ave through (S Neville st, Boundary st, Saline st) Traveling Beechwood Blvd right after Monitor st should be an exit Ramp to Forward ave that way you don't have to loop around through stop signs creating more confusion and traffic. The City is expanding more cars more people and instead of opening up more Lanes they are reducing with bike Lanes 😂

Amazing no one got killed

I know the guy who was driving the bus if you ever wanna talk to him mike

after repairs they forgot to slap it twice and say "it ain't goin nowhere"

So.... Who all is being fired and/or going to jail over this?

Badly made bridge. BAdly maintained! Shoulda been replaced ten years ago! The people traveling that bridge daily and only one time are at the mercy of the construction company who made that bridge. I’m so utterly grateful no one was killed. Thanks be to God n his mercy!

I know. Just remove the parts that broke. Looks good to me!

the state legislators should be held accountable for not using the gasoline tax for roads and bridges, they hired cops???

That corroded cross brace should have immediately triggered a closure. The city didn't even lower the weight limit. It's a shame Harrisburg diverted billions of dollars raised by Pennsylvania's ridiculously high gas taxes which were earmarked for infrastructure to other pet projects. If I ran my company that way I would be in jail.

That particular area in P-burgh is full of roads and bridges that are crumbling. It would be difficult for public officials to know which to prioritize for repair/replacement. Couple that with the fact that this area is a haven for social programs and you can see why the money wasn't used for infrastructure in a very long time. Oh, yes, they did some cosmetic repairs here and there such as patching potholes, etc. But a ride on Forbes Ave will reveal quite a bit of open decay in the roadways. The amount of money needed to catch up would be astronomical. There will likely be more collapses in the future.

This bridge was surveyed and corrective action was recommended. The PA gov't stole funds from infrastructure projects funded by fuel tax. They used the money in "underserved" communities.

Worked for mercer county bridge department years ago. Truthfully I'm surprised this dont happen more often. Was a lot of bridges that needed closed years ago that were in awful shape that couldnt be closed, and still habe not been replaced or even fixed. We would lower the weight limit and nobody payed attention. Is a metal grate bridge going to shenango dam that one side is closed, and has brush growing out of it yet the one side stays open. It's nice 2.4 billion dollars of our gas tax money was diverted to state cops.

When you’re given money to fix a bridge, do NOT spend it on bike lanes, lanes for self-driving cars and green energy initiatives !!!! (money allocated for repair in 2016)

Great animation but it's missing an important detail, I spilled a plate of spaghetti on the bridge deck late last October (I got spooked).

It's sad how most people in my area have been calling it an intentional collapse because Joe Biden happened to be nearby to talk about infrastructure.

The "victims" already planning to sue so expect prices to go up.

Am from Pittsburgh sum scary stuff

The Allegheny County Pork Authority........

Fact, all of Allegheny County school districts had a 2 hour delay on Friday morning due to snow. At 7 :00 am ,there would have been school busses on that bridge. Had there not have been a delay, this collapse would have been deadly. Odd that this happened the same day that Biden was due to speak about infrastructure.

Inspector: looks like the cross brace is coming off Engineer: well looks like we need to finish what it started Inspector: won't that be dangero... Engineer: SHUT UP DIMWIT

Great stuff... meanwhile the NTSB will pick their nose for 9 months trying to figure out the obvious...

Contrary to what Biden said at the bridge, the infrastructure bill would not fix this bridge. The ultimate reason fot this bridge failing was the lack of investment in infrastructure since WWII.

So some powers that be decided some braces came loose let's just get rid of them because maybe the people that designed that bride did not know what they were doing and it was cheaper to remove the braces rather than repair

Please stop with the "It could of been me" mentality. When something happens, everyone tries to connect themselves to the disaster..."I was on that bridge 10 days ago!." It COULD have been you OR me...but it wasn't.

The Big Guy has to have his 10%. As does everyone else. That is where the money goes.

it has now also been told that the state diverted billions of gas tax revenues from roads and bridges to fund law enforcement, and now the state is begging for more money.

Luckily no deaths!

I'm no bridge expert, but this bridge looks badly designed. I'd never trust one with such flimsy-looking supports.

I lived in PGH all my. Life all our bridges by down town are good. The one that are around the city are fucking terrible lol I t though

Well... One political party wants to give you healthcare & infastructure. The other doesn't.

First graphic should be how the Pennsylvania government diverts funds to repair bridges and roads to pay for more police.... for decades