Can the impact of a car going 10 mph kill a pedestrian?  The question
is about being struck, as opposed to being run over or otherwise
crushed.

Does it make a difference if the vehicle is a truck?

If being hit at 10 mph isn't enough to kill you, what speed does it take?

Don't worry, my friends, this is research for fiction, and no, it does
not take place in the Middle Ages.

Thank you,
Archae0pteryx

Archae0pteryx...

It seems that it depends a great deal on exactly where you're
hit and how you land. I didn't find any nice scientific 
studies with precise data, but was able to find anecdotal
evidence which seems clear enough.


On this Steven Jackson Games forum, Qoltar starts the
thread by saying:

"I got hit by a car today. REALLY...hurts like hell. Here's
 the thing - Driver ran the red light. I was walking the
 crosswalk - right of way. [...] Car was going 7-10 mph ...
 through a red light..."

He also notes he was fortunate enough to be wearing a leather
jacket, which, the paramedics told him, had probably saved
him from more serious injury, as they absorb shock. But he
said he only suffered from some bruising on his chest, some
fluid on his knees and aches and pains all over, and would
be going back to work the next day. 

Another member named The Wrathchild replied:

"I had a friend who was hit at 25mph, and he only suffered
 superficial damage from the glass of the windshield."
http://forums.sjgames.com/printthread.php?t=9403

The latter sounds like he was hit low and rolled up onto 
the hood, where he was hit by the windshield. We'll look
at this more closely later.


On Google's cached page of a MySpace profile for Eden,
a friend named Jason left a message stating:

"I got hit by a car walking across the street leaving
 physical therapy, yeah imagine that ****. I was hit at
 10 mph and flew back 30 feet in the air by a **** truck..."
http://72.14.253.104/search?q=cache:dsKqK89j2gUJ:www.myspace.com/edengiardino+%2210+mph%22+*+kill+-wind+-winds&hl=en&gl=us&ct=clnk&cd=36&lr=lang_en

He doesn't go into any details, but obviously he survived.


On this forum about Crow Seat Belts, Vanhag notes that:
"Having picked up my fair share of bodies from the dunes
 I'm going to throw my opinion in the ring [...] Sometimes
 even 10 MPH can kill a dune rider. It's a calculated risk
 we all take."
http://207.58.142.82/vw/forum/viewtopic.php?p=1324075&sid=598109470858240dad18335343e71f7d


But here's the telling part. In an article titled, 'The
TRUTH ABOUT HELMETS - Why Wear 'Em?', by Buzz Buzzelli,
citing extensive studies conducted at Dr. Harry Hurt's
Head Protection Research Laboratory in Paramount, California:

"If you were standing still and you fell over and hit your
 head on the ground, the impact would be equivalent to 13 mph.
 This fact has been verified through the previously mentioned
 research. Likewise, if you were sitting on your motorcycle
 in the driveway and fell over, it would also involve an
 impact of approximately 13 mph, more or less. The scary
 thing is, that's enough to kill you; many people have died
 from head impacts less severe than this!"
Much more on the page:
http://www.americanrider.com/output.cfm?id=1022077


On the other hand, of course, many a passenger has survived
a car crash or 35mph or greater by the fact of having worn
a seat belt, because, even though during the crash they are
quickly decelerating from a high speed, the seat belt absorbs
the shock in such a way that injuries are minimized.

Modern vehicles, by law, have bumpers that will absorb a
5mph crash without harm to the vehicle or occupants, so
they offer a slight dampening effect to a pedestrian.

Other factors include whatever protection is added by what
the pedestrian is wearing, the part of the body which is
struck, and so on. The more the impact can be spread out
over the surface of the body, the less severe will be the
damage, but if the force of impact is focused on one area
of the body, or if blows sustained subsequent to being
stuck are similarly focused, the chance of serious injury
increases, especially if those blows are to the head.

As is evidenced by movie stunts, if the pedestrian can go
onto the hood of the car and roll through the impact, he
has a much better chance of remaining injury free than if
he is simply struck and made to fly many feet through the 
air or rebound many times on the ground.

And clearly, their chances are much better if they can
avoid blows to the head during their motion subsequent
to being struck.


Nonetheless, it is also clear that if one is struck in
such a way that a blow to the head occurs during the
fall, death can occur when struck by a vehicle moving
even slower than 10mph.

sublime1-ga


Additional information may be found from an exploration of
the links resulting from the Google searches outlined below.

Searches done, via Google:

"10 mph" * kill -wind -winds
://www.google.com/search?q=%2210+mph%22+*+kill+-wind+-winds

"force of a car"
://www.google.com/search?q=%22force+of+a+car%22

---

Request for Answer Clarification by archae0pteryx-ga on 17 Sep 2006 00:25 PDT

Hi, Sublime1--thank you for taking my question!

As I interpret these responses, then, it sounds like you wouldn't get
killed by being struck at 10 mph but only by being knocked down in
such a way as to hit your head?  Is that right?  So the impact itself
at that speed wouldn't hurt you enough to kill you.

I need a serious injury to be caused by a slow-moving vehicle.  Sounds
like being struck isn't enough.  Is that your conclusion?

And so--if being hit at 10 mph isn't enough to kill you, what speed does it take?

Thank you,
Archae0pteryx

---

Clarification of Answer by sublime1-ga on 17 Sep 2006 13:43 PDT

Archae0pteryx...

Your interpretation of my results is essentially correct,
although, as noted, if the force of the impact is somehow
concentrated into a smaller focal point, it could cause
more severe and even fatal injury.

qed-ga has given you some of the math which is pertinent,
however, the term half-ton pickup is an older term for a
vehicle which could safely carry an *additional* load of a
half-ton, and actually weighs much more. See this page on
Findarticles for clarification:
http://www.findarticles.com/p/articles/mi_qa3707/is_200407/ai_n9421592

A modern truck's curb weight (unladen) can easily be 2-2.75
tons, or 4000-5500 pounds. Plug that weight into the formula
and the amount of damage possible is much greater.


Also, the fact that you're using a truck vs a car makes it a
bit easier, since they are more likely to have solid metal
bumpers and could have some nasty-looking attachments on the
front of the truck, such as the winch in the following image:
http://www.actionjackson.com/family/truck/images/20030719/winch.jpg

You'll notice that there are some rather sharply-angled edges
and lengths of metal that could act as a blade in causing an
injury, if the posture of the body was right. Also the truck
sits higher than a car, so the possibility of doing damage to
an internal organ and causing internal bleeding is much greater
than if the victim is struck in the legs by the much lower
bumper of a car.

Short of a winch, take a look at the ominous design of some of
the grille guards featured in the image on this page:
http://www.ustruckaccessorieswhse.com/ustaw_manik_grille_guards.htm

I leave it to your fertile imagination as to what could happen
if your victim was struck by the likes of this:
http://www.sportsmansguide.com/zoom/zoompop.asp?i=92011_ts.JPG&h=&w=&bgc=&ui=&mc=&cf=&nv=&c=&adid=195030

Here are some others to ponder:
http://images.google.com/images?q=truck+grille+guard

And, of course, you can always have the victim flung onto
the end of a sharp, broken, stomach-height tree branch by
the impact with the vehicle, guaranteeing internal bleeding.

Hopefully this will serve to fuel your muse with suitably
grisly scenarios.

sublime1-ga

You are terrific, Sublime1.  I don't know how long it would have taken
me to get all that.  Thank you so much!

Archae0pteryx

Hi Tryx

Decidedly YES!

Even less than 10 mph could be sufficient.

In fact, a nudge could be sufficient if the person fell badly.

Bryx

Hi, Bry--uh, hmmm.  Are you wearing my x?  It looks good on you, actually.

For my fictional situation, I want the pedestrian to be hit hard
enough to cause serious and possibly even fatal injury but not instant
death.  There has to be time to carry her someplace and worry about
whether she'll live.  And the vehicle has to be moving slowly because
it is traveling through the woods by moonlight, without headlights. 
So I need the fastest speed one could go under those conditions, and
probably the maximum possible injury.  It's not as easy to figure that
out as I thought.  Thanks for your comments.

Tryx

Howdy Archae0pteryx,

Simply have the pedestrian hit in the head by the vehicle.  Our victim falls
down to her knees, startled, tripping over a tree root, when the car appears
in the dark, unexpected.

Hi Again Tryx

The possibility of death is multi-factorial, depending upon speed &
mass of the vehicle, the place(s) on the person that are hit, the age
and health of the person, and the rapidity of getting aid to him/her.

Blood might come a-puvvering out and unless staunched ...

There's also a confounding factor because, in accidents where multiple
folk get injured, some people who are expected to survive don't; while
others who are expected not to survive do so.

Of course, being fiction, you can draw freely on your imagination.

Good Luck

Bryx

Hi Tryx,

Seems like everyone wants to help you. :-)
Ten mph in the woods by moonlight with no headlights seems about the
maximum speed, ca. fifteen/sec.  Depends on the track or road.  A half
way decent logging road for trucks could allow a higher speed for a
car in good moonlight if the driver is familiar with the road.
You might call the sheriff's office in Mendocino County.  They may
raid pot plantations by moonlight and have experience.
  
Odds are that the woman would be hit by a car in the knees, falling on
the dirt (?) road if she is struck from behind, or ending on the hood
if she was facing the car, which seems the less dangerous event.  If
she lands on the road, although the risk of a head injury is less than
on pavement, the driver may be slower to react, and could run over her
 - partially, anyway - crushing her leg or ribcage before s/he stops. 
The latter would be "better":  internal injuries, no immediate death,
but all sorts of possible reasons that she could die.

Yeah, I know, you wanted to rule out her being crushed.

Hmm, it might help if she tripped from surprise at the moment she
becomes aware of the car, not falling, but lowering her center of
gravity and being off balance, thus reducing the chance that she
bounces off the hood.

Truck:  Any vehicle with a higher and more vertical front will reduce
the chance that she would land on the hood, and some such vehicles
have "nice" sharper corners and edges than a modern car that could
give her a head injury: KO, concussion, worse brain damage maybe.

If it wouldn't be too contrived, a combination of the last ideas could
result in an immediate head injury.

Nice to see you back.  Scriptor has been moping around answering
questions about scam websites for lack of ones that tax his true
capacity.

Cheers, Myo

Howdy,

The injury to the bystander will be due to the energy of the impact.
So, to get some intuitive idea of the likelihood of serious injury at
10mph, let's figure out the energy of the vehicle, then figure out how
this translates to the bystander falling from some height, smacking
into the ground with the same energy.

   Let's say that the vehicle is a half-ton pickup. It has a mass of
1,000 lbs. It hits the victim at 10 mph. The kinetic energy is mv^2/2.
Plugging the numbers into the formula gives kinetic energy with a
magnitude of 50,000. How far does the victim have to fall to impact
the ground with an energy of 50,000?

   Gravitational potential energy is given by mgh, with m = mass, g =
acceleration due to gravity, h = height above the ground. Suppose she
has a body mass of 150 lbs. This then is 150 x 32.17 x h = 50,000. So
the height of fall is then (50,000/150)/32.17 = 10.36 feet. In
summary, she needs to fall from a little over ten feet to smack into
the ground with the same kinetic energy as the truck moving at 10 mph.

   So if it's plausible to expect severe injuries from a fall of about
ten feet, it's also plausible for the truck to hurt her as well.

Tryx,

Sometimes it doesn't take much of an impact to do a great deal of
harm. When I was in college, a guy who was in one of my classes died
after he collided with another runner during a marathon race. No
vehicles were involved: just one human running into another. It was
described as a "freak accident." Internal bleeding was the cause.

"however, the term half-ton pickup is an older term for a vehicle
which could safely carry an *additional* load of a half-ton, and
actually weighs much more."

   I guess I learn something every day. Thanks!

...Anyway, if the truck is now as little as 4,000 lbs, that translates
to the 150 lb victim falling from a height of about 41 feet. Indeed,
potentially very harmful.

Oh, how nice to hear from everybody!  This almost feels like a party. 
Bryan, Pink, Myo, have a hug!  << >>

Yes, I've been offlist for a long while, during which time some
changes took place.  I've also had to become less liberal in my use of
resources.  But when I get stuck on something weird (like this one),
here's where I come first.  And this was no disappointment.  Thank
you!

I don't know if I have anything going right now that would entertain
Scriptor, but I have a long way to go yet, so there's always a chance.
 I'm not building a church at the moment, but I am doing some things
with cults and mythology.

As for my poor victim, you have all added some great suggestions to
Sublime1's excellent response.  I will definitely base my accident on
your ideas.  The woman is not going to survive, but the boy with her
is only slightly injured, and he will.

Tryx

Tryx,

You may be interested in a graph on this pdf. A very small
probability, but it is still there. There's plenty of other info
available on the internet on the problem with bull bars on vehicles
and how they increase the risk of injury / death to pedestrians. Could
your vehicle have bull bars?

Car/Pedestrian Crash Severity by collision speed
Probaility of fatal colision
http://www.arrivealive.vic.gov.au/downloads/roadssafe/Speed_Keep%20it%20down.pdf

answerfinder-ga

archae0pteryx...

Thanks very much for the 5 stars and the elegant tip!

Thanks also to all who contributed with comments.
Pinky, that's an amazing and very pertinent story!
Answerfinder, excellent job at finding that graph on
pedestrian mortality at varying speeds!

sublime1-ga

"Sometimes it doesn't take much of an impact to do a great deal of
harm. When I was in college, a guy who was in one of my classes died
after he collided with another runner during a marathon race. No
vehicles were involved: just one human running into another. It was
described as a "freak accident." Internal bleeding was the cause."

   Yeah, but Pink, you left out a vital bit of information. It was a
marathon, but the runners were required in that particular race to be
knife-juggling the whole route. Since that terrible day you describe,
knife-juggling-marathons have been outlawed in at least 36 states.
(Not Indiana. We love our knives. They're sharp & pointy.)

qed, does your formula have the truck hitting the person as an elastic
collision or inelastic? I haven't dealt with much energy formulae for
a while, so just wondering?

Strikes me that 'glancing blow' is the keyword here.

mathisfun,

   That's a good point. The collision in this case isn't going to be
highly elastic. In fact, the victim/truck collision won't be exactly
equivalent to the falling-victim/ground collision. My idea here is
only to generate some rough, intuitive way of gauging the plausiblity
of a traffic injury by relating it to something that's perhaps
sufficiently familiar, falling from a height.

The woman and the boy, her son, are crossing the road in the dark. 
The woman is distraught and not sharply aware of her surroundings.  It
is 4 a.m., and they are escaping a dangerous place.

Suddenly the truck is there, moving at 10 mph without lights.  The
driver is inexperienced and has never met anyone on the road before. 
In a panic he steps on the accelerator instead of the brake.  The
truck jumps forward.  She shoves the boy out of the way, and he is
hurt falling over some rocks, but he is basically okay.  On your
advice, she stumbles as she is leaning forward to push him.  The truck
hits her pretty completely.

The truck doesn't have anything weird on the grille.  I looked at
those grille pictures, and they could do some damage, all right, but I
couldn't even guess what they are for.  This truck just performs a
nighttime shuttle mission and is no one's showpiece.  It's a fairly
old vehicle, too.

You guys are helping me tremendously to picture how this event takes
place and how badly the woman is injured.  Is there going to be a lot
of blood?

Thank you all so much--
Tryx

"is no one's showpiece"
Could it be damaged from a previous accident and not repaired? A
gagged piece of metal sticking out to the front from one of the wings
which stabs the woman. (then again, I may have lost the thread of
these comments and that's not now the storyline.)

> I looked at those grille pictures, and they could do some
  damage, all right, but I couldn't even guess what they are for.

Grille guards are insurance against the possibility that a large
object (a rock from a truck ahead of you, a deer, a young woman)
will penetrate the stock grille of the truck and damage the
radiator, rendering the vehicle undriveable out in the backwoods.
They also serve as mounting platforms for additional lights.
Some offer additional protection to the stock headlights.

Older trucks are less likely to have them.

Internal injuries won't produce much blood. The person might
exhibit blood coming up their throat and out their mouth if
the movies are correct in their portrayal of same, and the
bleeding is severe enough.

If the victim hits her head, there may be quite a lot of blood. Even
minor scalp wounds can bleed copiously. I had a horseback accident
when I was a child, and I lost so much blood from a scalp wound that I
needed a transfusion.

As Pink points out, a head wound can bleed quite profusely.

This brings to mind one of my favorite movie quotes.

"Ever seen blood in the moonlight? It seems quite black." - Dr. Hannibal Lecter

Have it during the winter.

The driver slams on the brakes, but the truck slides.

I like the idea of slowly sliding objects, red blood appearing like drops of
ink on the snow, the snapping noises of a hot engine cooling in the winter
night, and crisp white appearance of heavy breathing in the cold night air.

Hi Tryx,

I kind of have to ask why the guy is driving without lights, but you
don't have to tell us.  I assume there is a good reason related to the
plot  - beyond its being necessary in order to have her not notice the
truck.  Oh, "nighttime shuttle mission", ok.  :)

She would also have to overhear the truck:  wind, rustling autumn leaves, ...

Sometimes older trucks in the country have had grill protectors added
(called "roo-bars" in Oz), maybe a welder's self-designed thing made
of 3 inch pipe.
Also sometimes the front bumper has been replaced with a piece of flat
steel for pushing vehicles  - or 'cause the chrome bumper became
damaged  - and mounted directly to the chassis, instead of the way
modern bumpers are to absorb impact.
The top corner of that in the right place could give her "adequate"
internal injuries.  And since you have rocks in the area, she could
land on one and have a concussion and be KO.  These immediately
obvious injuries could be what is handled on the spot and later
elsewhere, while her internal injuries are only much later recognized,
when it is too late to save her.

As to the blood:  I agree with Sublime, a punctured lung or stomach
could/would show some blood, but a lot more could be filling the body
cavity, possibly from injuries that don't result in spitting or
coughing up blood.

The liver is well-placed for being damaged:
http://www.defence.gov.au/dpe/dhs/infocentre/publications/journals/noids/adfhealth_apr03/ADFHealth_4_1_45-47.html
http://www.gpnotebook.co.uk/simplepage.cfm?ID=1349189706
    You may prefer not to click on the photo, but the other links
could be of interest.
Or if she gets it in the back, maybe a ruptured kidney:
http://www.gpnotebook.co.uk/simplepage.cfm?ID=1342570570

Rupture of either organ, it seems, could result in enough internal
loss of blood to "do the job."   A search for:  ruptured liver/kidney
fatal
does find sites.

(I don't want any credit for being an accessory to this.  :-)

Cheers, Myo

Very picturesque, Denco.  Thank you.  Vivid story starter for you.

In my story, the accident takes place next May 2nd under the first
full moon of the month.  So--no frosty breath, no red, red blood on
pristine white snow.  More like--hmm, yes, I'm sure Hannibal would
know what it's like.

The second full moon of the month, of course, is known as a ______.

Sound of the truck:  might not even register with her, or if it does,
she is going to think it's on the road she's on and not on the road
that crosses it, which she doesn't know about.  She flatly does not
expect a vehicle to appear where this truck appears.  In fact, if she
hears it, she may think it's pursuing her and run faster, with less
attention to what's ahead.

Beat-up truck with raggedy front:  good idea.

Sorry, Myo, not going to explain my plot.  But you expected that. 
Thanks for adding so many gory details.  I especially appreciate the
suggestion of a way to handle looking bad, but with worse yet to come
in a delayed effect.

I am feeling pretty sorry for this expendable character whose only
function is to precipitate a crisis by dying on the premises of the
poor fellow who was driving the truck, leaving a son of unknown
origins behind.  Hope I can go through with this.  The last time I
killed a character in a grisly fashion, I felt so terrible that I
abandoned the story.

Tryx

Put a stream running next to the road.  The sound of running water would drown
out the sound of the truck.  The woman is carrying the boy over the stream.

______ moon, indeed!

I like the stream - nice one Denco

I would give her a glancing blow that knocks her into something (a
tree rooot ?) and breaks her neck - no blood, no sign of injury except
for a rag doll effect.

Is a vehicle really essential?

I would have her attacked by a vampire ...

Who spits out her blood when he discovers that her purity has been impaired.

Bryx