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The computer model that has been developed in this effort can be extremely valuable and is currently being used to design a better barrier at our facility, and also can be used to design better vehicles and better restraint systems in the future.

With that, I will turn it over to Dr. Raddin, who will continue with the injury causation analysis discussion.

DR. JAMES H. RADDIN, JR.: Thank you, Dean.

We're going to talk now about the other end of this process. Dr. Sicking has given you the vehicle dynamics part. We're going to now look at some of the clinical injuries that were involved. What we find is that there were some injury to the head, and clearly it was a head injury that produced the death.

What we find first is that there's an area of contusion to the occipital region, which is the back portion, back lower portion of the head. That contusion was measured to be approximately 8 by 5 and a half centimeters. Now, what that means is about the size of my Texas driver's license.

And if you put that here, that's about the size of that area of contusion. Now, a contusion is a bruise, and a bruise is an area of hemorrhage in the soft tissue without a break in the skin, without a laceration. That indicates blunt trauma, blunt impact to that portion of the head.

Similar findings were noted on the right, but the only measured finding was noted on the left. And there was a notation that some more scattered hemorrhages were present and apparently smaller areas of hemorrhage present more to the right side of the scalp and towards the top.

The injury itself is a fracture to the base of the skull. Now, the base of the skull, the slide that you have up there, is looking at the base of the skull from the inside down. Let me just tell you, the base or the floor of the skull is the part of your skull that you can't put your hand on. You know, you can touch the upper part of your skull. But the base of the skull is a location where your neck attaches to your head.

But there is a floor, a bone across there, upon which the brain rests. If you look at it from the inside, as we have in that particular diagram, it says that we have a ring fracture at the base of the skull. Now, a ring fracture, if it's a complete ring fracture, is one which forms a circle typically around this foramen magnum, which is a hole in the bottom of the skull through which your spinal cord comes out. The ring fracture involved fracturing through several of the bones in the base of the skull. It's not a perfect circle. It's a ring fracture; it's an irregular ring. When it's a complete ring fracture, as this was, that ring fracture is a closed figure around the foramen magnum.

Now, there was wider separation of the bone fragments in the front, but it was described as a complete ring fracture.

There was also noted an abrasion about an inch by six-tenths of an inch or so over the right side of the chin. There were other marks on the body, including abrasions on the torso, one which was over the left clavical, which is the collar bone. That's in a distribution of the shoulder harness. There were other abrasions on the torso and a contusion, another area of bruising, to the mid abdomen.

There were multiple rib fractures. There were rib fractures that for the most part, in fact all of them, were on the left side of the chest. These were, for the most part, anterior rib fractures. They were rib fractures which showed very little bleeding around them. And there was also a fracture of the breast bone, or sternum, which was at about the location where the third rib comes in.

You'll note there's a prominence of injury to the left side of the body. There's left rib fractures, the left mark across here, that continues in other places because we've got a left fracture dislocation at the ankle.

And the left part of the body, as it comes -- is exposed to the greater amount of trauma here is consistent with some of that occurring as a result of the left side of the body moving forward more than the right. And that's consistent with what you would expect to find if a left lap belt separates under load before the forward motion is completed.

The cause of death, as listed by the pathologist who did the examination, is blunt force injuries of the head. That is the way that the cause of death was determined.

And the findings that he had there are certainly consistent with that. That gives you an idea of the injuries that we are trying to establish the cause of, in the context that we have in this crash. Dr. Sicking has talked about the vehicle dynamics. Let me just review some of the things that I take from that.

One, he said that this was a pretty severe crash. A 43 mile per hour velocity change is about what you would expect if you were sitting in a parked car and a car of similar size, similar mass, approached you at about a 22-degree angle from the front at a speed of 75 to 80 miles an hour. That's not a minor crash; that's a severe crash and it's one in which you would expect generally poor results in passenger car settings.

But even with the more advanced protection systems of a race car, it represents some challenges. Things have to work right if that's going to be protected against. The principal direction of force, or the line of action of this, involves a line of action from two different crashes. And it makes it a much more complex analysis than perhaps has been appreciated.

First of all, we had a lateral force that derived from the contact from the 36 car, and that came in at about 8 degrees off of straight lateral. The second was the impact with the wall, which when you resolve those numbers, comes out to about 22 degrees to the right forward. It's where that force is coming from and occupants tend to move opposite and parallel to those principal directions of force.

Now, as we move from vehicle dynamics to occupant kinematics, we try to understand how the occupant moved. One of the pieces of data that we have for that is looking inside the vehicle. When we look inside the vehicle, we find a number of findings. One is that there was contact with the steering wheel.

The steering wheel is deformed. This is the steering wheel, this is the hub where it mounts. These are spokes which are bent. There are abrasions in several areas around the rim, and when you put that hub on a flat surface, part of that steering wheel is pushed significantly in by a distance of roughly five inches.

And part of it is actually pulled out a little bit by a distance of about two inches. It would normally operate at about five inches straight across, if you put that together.

There were abrasions on several areas with some imprints, scuff marks on the edge of the wheel. This is a close-up looking at the edge of the steering wheel from the side.

There were marks on the seat. The seat surface is covered with a velour cushion, or pad, over the top of it.

A portion of that velour -- and I'm talking about this area from right around here and this area right around here - actually was melted from motion of the occupant. And you note that that motion was only on the right side of the seat. These are the areas of melting right here. And they go in the angle that Dr. Sicking's reconstruction tell us.

This was at about a 22-degree angle. When I put a light on those, you can see there's just a scuff with melting of portions of that fabric coming this way. There's a support structure that comes across here, so it forms a little ridge, and it was contact here and then right over the ridge, where we see those abrasions.

That says the occupant moved forward and moved forward considerably under force during the event.

There was also findings on other portions of the seat. As you look down into the seat cushion, there is a support wing that would normally be to the right of the torso.

Your arm would typically go over that. This is a support structure. And it's not -- it's just kind of a positioning rest; it's not something that is designed to force you into that position. The underlying metal of that support structure is bent to the right. When you look right at the top of that support structure where the velour transitions to what looks like a vinyl, there is a scuff with some fabric that is bunched over to the right side, and there's a scuff that goes to the right and then a subsequent scuff, a higher speed scuff, going forward.

When you look at that up close, you can see bunched material over to the right. And there's evidence that the occupant went to the right, as well as going forward.

We have a more complex crash here.

As you look at the toe pan, this is the pedals. Here is the steering column penetrating through the toe pan. That's the floor board area in the front. There is a scuff just to the left. And as you recall, there was a fracture dislocation of the left ankle, indicating further forward motion of the left side in towards the floor.

Those marks help us understand the occupant kinematics, and they are consistent with what we see in the vehicle dynamics.

We know that occupant kinematics follow from Newton's first law, because Newton's 1st Law says an object in motion remains in motion until acted upon by some force.

The force typically begins by being applied to the car. The car gets changed and the occupant in motion is the occupant inside and continues parallel and opposite to the principal direction of force. And when that happens, we know how that looks.

This happens to be a picture of me in one of my crash tests back in the Air Force. It's a lateral hit. It's in a direction within eight degrees of the lateral motion of that other hit that we talked about, from the 36 car.

It's in the opposite direction. Here, I'm moving from a hit that was on this side, and I'm moving to my left. As you recall in the 36 impact, it was on the right side. That occupant would move to the right.

I'm in this harness wearing a harness that is both stiffer and offers greater lateral support because of the way the harness is implemented with some double straps up here.

But it is a five-point harness with a central buckle, a crotch strap, two lap belts, and I'm wearing a helmet.

The velocity change is probably -- it is a little higher, it is a little higher than what was experienced in the 36 car but the acceleration level was pretty similar. The motion you would expect from the occupant of the 36 car would, in fact, be greater than what you see here because of the differences in the restraint system.

The other thing that you can see as you look at this is that you can also understand that helmets obey Newton's 1st Law, just like people do. And as the occupant tends to go this way, the helmet starts rotating over my head. It does so less in this particular case because I've got a nape strap that comes across under the kind of -- on the back of my neck that helps retain that helmet but it still opens up the area in the occipital region, even with that helmet. You would expect greater rotation than in Dale Earnhardt's helmet.

So helmets obey the same principles, and I've looked at that helmet and it does show evidence of having moved with respect to the head. The microphone attachment, for example, has been pushed up and imprinted in to the edge of the helmet on the left side.

So the conclusion is that not only did the occupant move to the right, but the helmet tried to continue going further and rotated on the head. I would like to show you an example of the type of motion that I'm talking about. This is not a great quality video, but I'm going to show it to you anyway.

It's the best copy we have. It's a copy of a video that was made in which Johnny Benson is driving a car. We thank him for providing this. It makes an impact to the wall, not a big impact to the wall. He ended up driving the car away. It does not have the kind of damage.

But here he is. Here's his helmet. Here's a side support here. Hands on the wheel. Here comes the hit. That's not a big hit. But did you see that he moved in response to that motion, or in response to those forces on the car?

This is a kind of a still frame from the video, but you can kind of get a sense of the helmet. If you can see, he's kind of doing what I did in that crash. Your head doesn't just rotate this way; it rotates this way in a roll but it always -- you end up looking towards the floor and the helmet is moving further than he is. His hand is off the steering wheel.

As he comes back, the helmet, even in a full-face helmet here, is displaced, even still as he comes back, at a point that is still displaced with respect to his head and not lined up with it.

What we understand from this impact analysis and from looking at the evidence in the vehicle is that a complex set of kinematics occurred because in these kinematics, the occupant started from generally in this position. This would be basically a normal driving position for Dale Earnhardt. He tended to drive with his head to the left, more over towards the window.

I don't know exactly where his head was at the time this crash took place, because as he's starting to steer, he may have looked to the right, he may have moved his head off the headrest; I don't know those things.

But I'm going to give you just a representative scenario in drawings that are not intended to depict precise motions. I can't tell you that his fingers were just this way or his arms were just this way. But we're talking about a set of complex kinematics which I'm going to try to represent with these drawings.

During the impact with the 36 car, he would have necessarily responded in a way at least as much and potentially significantly more than did Johnny Benson in the video clip you just saw, or in my crash test. The helmet would rotate over and the area where we're talking about finding evidence of contusion on the head is located right here.

That puts him in a position where the left side of his head is leading instead of the front portion of his head. I would expect him to be in the process of that response. He is not likely to be at the full amount of that response.

He's probably coming back some from that response, but the 36 car impact occurred approximately 400 milliseconds before roll impact. That's approximately twice the duration of an eye blink that you just did.

The 36 car hits, the response is here, and then as an occupant would move forward into the right at about a 22-degree angle, the head would be trying to go to the right but as the torso belt arrests the torso motion, the head is going to begin to swing back towards the left after having displaced forward.

Now, we don't know where in the process the seat belt separated. If we knew exactly when that was, we could be much more specific about some of these things. But we do know that the seat belt separated under load at a time that allowed further excursion forward and we know that when the belt separates, the buckle moves further forward and that's where the torso straps are attached so the torso can move further forward and that means the head can move further forward.

That occurs with the left side of the head leading, and as it swings back around, a greater displacement occurs and there are two opportunities for head contact to produce blunt force injuries of the head.

One is in conjunction with contact with the steering wheel rim, with the helmet displaced. And the other one would be on rebound. Let's look at the steering wheel rim potential first. With the helmet displaced, contact could occur directly to that portion of the head. It could occur, and would be expected to occur, in a fashion not with the head pushing forward on the steering wheel.

These steering wheels are designed to be hit and pushed forward under impact, and they move forward with a velocity with a force applied somewhere in the neighborhood of 200 to 300 pounds in that neighborhood as you push forward. That provides some ride down of the head against it. But if you hit a ring structure more radially, it's stiffer. When you measure it, it's about 1300 pounds.

That provides a significant opportunity. When you go through the kinetic analysis, you find that the velocity between the head and the steering wheel that could develop in the distance it would take to get there would put this well above 30 miles an hour and sufficiently powerful an impact to produce a basilar skull fracture in conjunction with the head tension -- or neck tension that would also be present. Rebound provides another opportunity, because as you rebound, the head is pulled back by the torso. The helmet wants to continue to stay forward, and so there's an even greater displacing characteristic of the helmet as it comes back.

So we see two specific opportunities, and I can't tell you which one of those occurred. But the kinematics are consistent with that kind of motion, and then as the person makes a secondary rebound, additional modest contacts would take place that would not expect to be -- you would not expect them to be injurious but would certainly move the helmet back into a normal position.

Well, we need to talk a little bit about biomechanics and we're done. We need to know a little bit about ring fractures. I won't try to educate you entirely about that, but I'll make some comments about it. These are part of the evidence for what we conclude as being a blunt force impact to the head, as the pathologist stated was the cause of death in conjunction with some neck tension.

We'll talk about our basis for that. We'll look at some alternate theories that have been talked about around the country.

And we'll look, I'll at least mention to you, that I went on and did sled testing in this case and I put a hybrid three anthropromorphic test on me, balanced it and put it in a size of Dale Earnhardt, put this in a position deviated to the right and got motion forward and into the steering wheel and then contact on rebound.

The rebound contact's a little different in the sled test, but taking into the fact that the rebound should occur more to the left, it certainly provides a basis for significant contacts in either of those two positions.

Let's talk a little bit about ring fractures. First of all, they're relatively common fatal injury in car crashes. We see them frequently. We tend to see them as a result of impact to the head. You don't have to impact the floor of the skull. You typically can't access that because the neck is attached. But you can impact the head in a number of different locations and produce ring fractures to the base of the skull as a result of either tension, compression, or torsion, that's twist, on the skull base.

The same kind of fracture can be produced from a number of different kinds of impact. You can get the same kind of fracture from a head impact that you get from straight torsion or from hyper extension type of impact.

Jim Benedict and I have concluded that a head impact with neck tension likely was the cause of the ring fracture for Dale Earnhardt. We base that on the autopsy finding which says there was a contusion and says it was a blunt trauma. You'll see that much of these bases are portions that were developed during this investigation. They were not present and not available to everybody to start out with.

(go to www.maxpages.com/earnhardtisno1/Earnhardt_Report_Trnscpt_Part4 to see Part 4 of the transcript)

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