SAM SHERIDAN: This is a place that has
seen a lot of human tragedy.
You can bundle it up under the blanket of a curse,
but you can't deny that there is something at work
here, some relationship between West Virginian industry
and a seemingly endless cycle of calamity.
And since Austin Caperton won't be providing any answers,
I'm turning to a trusted old buddy--
science.
So what we do in this lab is we build stuff.
And we break it to figure out how to make it stronger.
What a cool job, man.
SAM SHERIDAN: No disaster is woven into the local folklore
of West Virginia quite like the collapse of the Silver Bridge.
I think there's reason behind it.
Yeah.
It just didn't happen to happen.
They said that the Moth Man appeared
before the bridge fell.
It's like a legend.
SAM SHERIDAN: Although I'm fairly certain a flying cryptid
didn't cause this disaster, the Silver Bridge did collapse
at the exact spot where the Battle of Point Pleasant
was fought.
And some say that was the cause of Chief
Cornstalk's dying curse.
So what does science have to say about
that peculiar coincidence?
MATT HEBOON: This is a model of the Silver Bridge.
SAM SHERIDAN: Cool.
So the Silver Bridge was similar to a suspension
bridge except that the suspension
cables were actually eyebars.
So tell me exactly how the Silver Bridge failed.
What happened?
There was a flaw.
It was actually located at the end of the eyebar.
That flaw was extremely small, and actually
wasn't visible because it was hidden
under the cap of the pin.
And in this case, the very small flaw initiated a fracture.
Can you show me what that would look like?
Yeah.
MATT HEBOON: OK, so we're going to apply a tension lug,
meaning we're going to pull on this.
[creaking]
What's this kip?
What is that.
So a kip is 1,000 pounds.
So we're at 0.21 thousand pounds,
or in other words, 22 pounds.
It's incrementally adding load.
This no longer is contributing at all.
All the force that was in this component
is now dumped into this one.
SAM SHERIDAN: Right.
In the case of the Silver Bridge, this happened so fast.
The first one failed and immediately--
[snap]
Let's-- let's do it on our model.
MATT HEBOON: OK.
SAM SHERIDAN: And here's where we smash
stuff in the name of science.
So we're going to simulate the fracture of the eyebar
by cutting one of the yellow strings.
[dramatic music] When one eyebar failed,
there just wasn't enough capacity in the rest
of the system to resist all of the weight of the structure,
and therefore the entire bridge collapsed.
SAM SHERIDAN: So the Silver Bridge collapses.
What's the way this could have been prevented?
MATT HEBOON: The original designs for this bridge
called for a suspension cable.
But they decided to opt for a less redundant system
with the eyebar chains, which allowed them to dramatically
reduce the cost.
But it also dramatically reduced the redundancy in the system.
SAM SHERIDAN: For those of you at home
who never took an interest in civil engineering,
let me spell it out for you.
Redundancy equals safety.
So if they hadn't done this with the lowest bidder,
there's a possibility that that failure would have happened,
but they would have had enough redundancy that the bridge
wouldn't have collapsed.
That's right.