Why did the entire bridge collapse in Baltimore when it was hit by a container ship?

After the collapse of the Key Bridge in Baltimore, many are wondering how the entire structure came down. Engineers say it’s mainly due to the bridge type-Truss.

In Truss bridges, there are no cable supports. All of the structure you see above the deck is designed to transfer the load to the eventual supports or piers that head underwater and into foundations.

When you take down one of those piers, the shape changes and the force of the crash is attempting to span twice as far in order to reach the next pier.

[TallulahSoie]

I can't believe removing a critical part of the foundation of a structure causes it to fail.
Everyone knows engineering relies on magic.

[staunchlyspeaking]

Correct, it is not a suspension bridge.

[hangten]

Who cares about the falling bridge, they should report how the ship ended up hitting the bridge.

[stacysanders-we]

Did you see the size of that ship? The ship and it's owners are at fault and liable. It's not as if a bridge can get out of the way.

[wetdog]

Considering that’s it’s not a cable stayed or suspension bridge it’s not a big shocker that there’s no cables. Do some actual reporting instead of hopping on the trauma train

[halbos]

Not very many people know anything about structures of any type, much less that of many types of bridges. Sometimes a detailed explanation is warranted.

[serendipitous_discoveries]

But what was the original route supposed to be before the ship lost power? From this video it looks like it wouldn’t have fit under the bridge, but I saw an article saying there would have been plenty of room if it had been able to go in the channel under the right part of the bridge

[alanstevens]

100, 000+ ton ship. Size and weight of the USS Nimitz aircraft carrier.

That whole truss structure probably weighed less than 1/2 of that.

No bridge is designed to withstand a 100, 000+ ton ship moving at 8 knots.

[michaelhaney]

No cable stays wound have saved this from happening...
No bridges could have survived it ..

[bobbym.]

Prayers to the 6 people on the bridge at the time of this collapse.

[allendove]

This is why in Hampton Roads, there aren't any bridges of that nature along the James and Elizabeth Rivers or Chesapeake Bay until you get past the Navy. The bridges and tunnels are probably too expensive and unnecessary in that area. Something like this can keep them from getting in or out.

[thomasjamison]

Well, of course. The very big difference between the collapse of a truss bridge when one of it key supports is knocked and that of a cable span bridge when one of it's supports is knocked out is that they both fall down and go boom.

[Civil_Engineering_Decoded]

This bridge is truss with continuous section, and also the load is distributed with vertical suspenders( Stressed bars) .

Generally these vertical suspenders are designed to carry vertical or very minimal transverse load( depending upon its type or fixing technique) .

As the Ship hit exactly on the pier from where load transfers to the ground, it shattered the complete bridge .

[jasonguest]

I'm not sure you could find any bridge that would stay standing after being hit by a fully loaded container ship at 8mph.

[sammyday]

I love how everyone who can’t even do a simple math problem suddenly becomes a preeminent engineering expert.

[get_some]

Now I'm not an engineer....but I'm gonna say that in engineering terms. "It got hit by a f***ing ship!" I don't think you can blame engineering whatsoever, even if a few bolts were rusted or whatever. The truss style is the design of this type of bridge, it's supports, take out a support and oh no!. Try driving a car meant for 4 wheels with 3, see how it works out. That's like the world trade centers being like, "didn't know a Boeing was gonna fly into it"

[swisscottagecleanairaction]

So far no accurate time line exists that shows when the ship exited the channel it was meant to be in to pass the bridge unharmed. Once you establish that you can investigate how those steering spent the remaining minutes until impact.

[bigedsbeachsidegarage]

It became unbalanced. As one structure, it's strong. Take one of the MAIN supports away and it falls. Take the support away with lateral force, and it will completely destroy itself.

[skanthaadsigns]

Fully laden container had more weight & velocity providing greater lateral force to overcome the bridge downward force from its weight... The bridge is assembled based on "weight balance and transfer".

[ronniechavez]

Its not the Bridges Fault!! Also Ships dont Drive into Bridges Regularly like cars. In other Words Blame the Shipping Company