Portion of Interstate 95 collapses in Philadelphia after tanker fire burns under overpass (Wilson: credit, how much)

[RetireinPA]

Originally Posted by Cloudy Dayz

Looking at the Streetview images of the bridge, it doesn't appear there was any concrete to crumble. I have never seen a bridge design like this myself. It looks like it was just a metal deck on top of steel beams covered with an asphalt surface. No concrete whatsoever on the underside.

At first it would appear like a brillant design. No concrete to crumble, break off and fall on traffic below. Easy inspection of the bridge beams for any corrosion. But I think this incident shows the weakness in the design. Concrete encasing would have acted like a heat shield. I suspect even if the bridge had concrete on the underside, ultimately it would have still collapsed, but probably not nearly as quickly as it did, and maybe the entire bridge structure would not have been compromised. It's kind of scary how quickly it collapsed from the heat. And the southbound lanes buckling the way they did is not good.

Betcha $5 that steel you see underneath is what held up the reinforced concrete until it cured. A steel deck bridge, and the waves it would pass, would make 'galloping gertie' look like a meadow...

[Duderino]

I don't think people are quite grasping that this is a major national interstate, for which a ****ton of businesses, local residents, and East Coast travelers depend on for daily life. I knows there's incredibly little confidence in these days for government to address emergencies and solve problems these days, but I don't think we're looking at longer than a couple months, tops, for a least a "stop gap" fix.

The economic impact is very high, and you can bet this will be top priority for tons of employees at PennDOT and the federal DOT until it's repaired.

[Reggiezz]

Why is there no information reported about the driver? Dead or did he escape? Why has he not been identified?

[Cloudy Dayz]

This article I think backs up by theory that the lack of concrete on the bridge caused the collapse.

The girders that supported the collapsed I-95 bridge appear to be made of steel, a Drexel University engineer said after looking at Inquirer photos from the scene.

That means they were more susceptible to heat than if they had been made from steel-reinforced concrete, said Amir Farnam, an associate professor of Civil, Architectural and Environmental Engineering.

“There is no concrete surrounding them,” he said. “That means they are very susceptible to any sort of high temperature.”

Steel melts at temperatures above 2,500 degrees Fahrenheit, depending on the alloy used, but the metal starts to fail at temperatures well below that, Farnam said.

The metal loses about 20% of its strength at 750 degrees, and about half of its strength at 1,000 degrees, he said. Those temperatures are easily achieved with a tanker fire like the one that occurred Sunday morning, he said.

“When you have a fire like this and it lasts for a few hours, the yield strength of the steel decreases drastically, and it fails,” he said.

Repairs for I-95 collapse in Philly expected to take months; Shapiro to issue disaster declaration

Unfortunately it didn't even take hours for this bridge to fail. It appears to have buckled and collapsed within a few minutes. I don't like that bridge design. Reinforced concrete should be a requirement for bridges like this. A bridge is going to collapse under conditions like that, no matter what. But it would be nice if it could last enough for authorities to shut traffic down before it collapses.

[PHL10]

I think I read somewhere that this span had to be steel girders since they didn't have the clearance below if they would have used reinforced concrete beams.

Originally Posted by Duderino

I don't think people are quite grasping that this is a major national interstate, for which a ****ton of businesses, local residents, and East Coast travelers depend on for daily life. I knows there's incredibly little confidence in these days for government to address emergencies and solve problems these days, but I don't think we're looking at longer than a couple months, tops, for a least a "stop gap" fix.

The economic impact is very high, and you can bet this will be top priority for tons of employees at PennDOT and the federal DOT until it's repaired.

That is my feeling as well. This is a hugely big deal. Between engineering and regulation, this is something that can't be allowed to happen but it happened because it was such a freak occurrence.

[Cloudy Dayz]

Originally Posted by PHL10

I think I read somewhere that this span had to be steel girders since they didn't have the clearance below if they would have used reinforced concrete beams.



That is my feeling as well. This is a hugely big deal. Between engineering and regulation, this is something that can't be allowed to happen but it happened because it was such a freak occurrence.

I have to wonder what would have happened if this truck had been an oversize load, instead of a tanker. Oversize loads hit bridges all the time. Usually they crash into the concrete and cause a lot of damage, but the concrete protects the steel girders, and the bridge doesn't collapse. But if a flatbed truck with a large piece of heavy equipment on it took the wrong exit and drove under this bridge it would hit directly into the steel girders, and it could collapse the bridge faster then the fire did.

If clearance is a problem there are solutions to that. The pavement under the bridge can be torn out and dropped down a few feet. Or the bridge can even be jacked up a few feet. Though that would take a lot more work. This bridge design is just bad.

[BeerGeek40]

Originally Posted by Craziaskowboi

I-85 in Atlanta was rebuilt within about six weeks after it collapsed. I expect the same of I-95 in Philadelphia.

We'll see, but that seems optimistic.

[MarketStEl]

Originally Posted by Cloudy Dayz

I have to wonder what would have happened if this truck had been an oversize load, instead of a tanker. Oversize loads hit bridges all the time. Usually they crash into the concrete and cause a lot of damage, but the concrete protects the steel girders, and the bridge doesn't collapse. But if a flatbed truck with a large piece of heavy equipment on it took the wrong exit and drove under this bridge it would hit directly into the steel girders, and it could collapse the bridge faster then the fire did.

If clearance is a problem there are solutions to that. The pavement under the bridge can be torn out and dropped down a few feet. Or the bridge can even be jacked up a few feet. Though that would take a lot more work. This bridge design is just bad.

The bridge had standard clearances; there were no low-clearance warning signs on the Cottman Avenue northbound off-ramp.

A friend of mine suggested that simple cross-bracing of the steel support girders would have prevented the collapse. But if it was the heat that weakened the steel, then maybe not even that would have worked.

As for the design: I think that if you go look at some of the sections of the viaduct that carries I-95 over much of both Northeast and South Philadelphia, you will find that the same sort of steel support is used, just with thicker beams because of the greater distance covered.

[NYtoNJtoPA]

The driver is dead. His remains were found where the bridge collapsed. Saw that this morning.

This is a road I depend on regularly to get into the city. I planned my commute this morning around it, managing to avoid "The Boulevard" which is what detours are directing motorists to use. I avoid that road like the plague. Looks like I'll be using 295 in South Jersey a lot in the next few weeks. Glad my company covers tolls.

We all know how long there has been construction on this road. I am hoping it is not longer than a few months. The governor declared it an emergency and is getting federal aid. I can't fathom what it would be like in the winter if it's still closed. Local roads stay closed sometimes for over a year, but this is an interstate highway, a major throughfare that spans the entire east coast, not a small road. I'd like to think everyone would be pushing to get it done ASAP. Maybe it will be a wakeup call for these union thugs who want to stretch construction out as long as possible.

[NYtoNJtoPA]

Originally Posted by thedirtypirate

Even worse, it was on the new deck side.

Yup. Saw that too. They said the bridge was only 10-12 years old!