20 July 2010

Flying Cars....

From the Cop side: Many years ago when I was a rookie cop first learning how to do police work, I was assigned to work with a traffic officer. I’ll call him “Jim.” I had the privilege of spending a whole 2 weeks with Jim and learned a lot about crash investigations. (There are very few “accidents” but lots of car crashes.) Most citizens call them accidents, but when a trained investigator looks at the mess, he or she can usually figure out in a short time which driver or drivers were at fault. The usual reasons for the “crash” are because one or more drivers violated some traffic law, or law of physics.
When you take away that "one factor" that if it had not happened, you wouldn't have had a crash---that is then your Primary Collision Factor PCF. 

One method I was taught at got pretty good at was estimating the speed a vehicle had been traveling at just prior to the crash. There were a few ways to figure this out, but one good bit of evidence often found was the skid marks left on the pavement.

Friction and"The Stopping Force"

A skidding vehicle is decelerated at a rate which is related to the frictional force generated between the skidding tires and the roadway. The friction is dependant on the weight of the "coefficient of friction".

(This may look like Bosnian writing, but it’s not) µ = V2 / 255 S

The following steps are used to find the coefficient of friction:

Now keep in mind, in my early days of police work, we didn’t have the really good pocket calculators that are around now. Some of this we had to do on paper.

Then I found a book with a chart that had all kinds of skid factors, so you could just look on the chart and be close enough.

I got pretty dang good at this shit…then something happened…in the 1990’s they came out with anti lock brakes. So much for all that skill and training…now the dang car would try to actually help a driver stop without skidding. Crap, no more skid marks.

But what do you do when the car you are looking at during an investigation violated the laws of gravity? Many of these flying cars are still unforgettable over 20 years later.

1980: I was on patrol in the nice friendly city where I started out working. I was dispatched to a motor vehicle accident with possible injuries. I responded from a few miles away with my emergency lights and siren on (Code -3). Upon arrival, I found a 1970’s something GM product on its roof with several yards (meters) of debris scattered along the road. The speed limit on that road was 35 MPH, so at first I had a difficult time comprehending how a car could end up like that.

I parked my marked patrol unit in a manner to protect the crashed vehicle and myself while I checked for injured persons. When I got up to the crash, all I could see were a pair of female legs sticking out the passenger side window. That was the only part of her body I could check for a pulse---but I lacked the Human Anatomy background at that time to know where to find a pulse besides the carotid and radial pulse (neck and wrist).

So, I did the next best thing and yelled: “Hey lady, are you OK?”

She moaned and moved, so I figured she was still alive. Then she started to swear…and that was when I could smell the “strong odor of an alcoholic beverage upon her breath and person.”  She was alive. 

No need for me to say that she was a very intoxicated driver. She went to the hospital and was booked in abstention due to her injuries. She fully recovered from the crash by the next day.

But, what a mess. I had to do the “T.C” (Traffic Collision) report. I blocked off a lane of traffic and got out my “roll-a-meter” and walked from where the car had landed, back to where it had first impacted the curb, brush, fire hydrant, street signs etc. It left only 50 feet of locked 4 wheel skid marks before it impacted the curb.
Then it lost control, went sideways, and landed on its roof….and slid for about 100 yards.

I had no way to figure the speed of a metal roof slide….maybe at least 85 MPH?

More flying car stories to come.


Momma Fargo said...

Love it! Isn't technology great? Get rid of all the old formulas because there is something that causes a glitch or loophole. UGH.

~J said...

Crazy drunks... drivin' with their legs out the window.

Coffeypot said...

The best first three minutes of any movie ever made was Top Gun with Danger Zone playing.

And they don’t make cars like that anymore. Now they fold up like crushing a beer can in your fist.

Anonymous said...

1. Laws of physics, eh?
2. Once had a security company. Guarded stuff for the Navy.
3. Had GSA pick-ups with light bars, radios, etc, that cruised the fenced area looking for intruders.
4. Speed limit was 10 MPH.
5. One 2AM, one of my brighter lights goes off the road.
6. Leaves 150 feet of rubber and rolls the truck three times after he goes over the embankment.
7. Standing in front of me at office hours, he says: "Honest sir, I was going 10 MPH."
8. My reply: "Son, you're going to jail...."
V/R JWest

Georgia Drivers Ed said...

Nice Post, using this we also got to know how the investigation goes on car crashes

Jay said...

When you said flying car I thought you meant something like the Terrafugia and after reading your post again I still think you were, just an earlier model.

CI-Roller Dude said...

The more things change, the older I feel. or something like that.

~J, We had contacted this lady several times in the past, and she was always a bit impaired. I'm not sure if she had been driving with her legs hanging out the passenger window before the crash.

CP, now when new cars crash, the bumpers peel off and all the beercan metal folds up.

JW, I'm pretty sure he was exceeding the speed of stupid.

Driver's Ed, now days I can just take a few minutes to look at most crashes and tell what happened. I just do all the fancy stuff to make folks happy.

Jay, Huh?

Jay said...

Sorry CI I should have given a link for the Terrafugia.


If that doesn't work just search under Terrafugia.

Somehow I don't think it will take off (the idea that is not the car). I think I'll be keeping my four wheels anchored to the ground.

Hogday said...

Christmas Day, West London many years ago, empty roads, 2 police cars from the same division, both many miles off their designated patrol area, have collided with each other near London Heathrow Airport. Driver 1 states, "I was following Driver 2". Driver 2 states, "I don't suppose you'll believe this, but we were following a bright light in the Eastern sky?"

CI-Roller Dude said...

Dang it, I just had coffee spew out my nose all over my keyboard.

Some of the people I've worked for didn't get too worried about where we drove to eat a meal...as long as it was within a ...well, they never really said how far we could drive...but I always managed to get to the calls in time. But...in 31 years, I've never crashed a police car.

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