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Does anyone know of an equation or calculation that can tell you how fast a car was going at the time of an accident?

I know there are experts who do this and there's been some question about how fast I was travelling at the time of my accident. I say it was 50 and the police say it was more. The only thing that's at stake is a $30 dollar ticket for drivin at a safe speed. The lady that pulled out in front of me is pleading not guilty to, I believe, blocking a roadway . I was cited as above and am pleading not guilty as well, the speed limit changes from 55 to 45 there but it's less than 100 ft after the speed change. I think the officer is full of it because I was not 'moving' as he put it. The lady pulled out in front of me right as I was passing by. How she thinks she didn't do that is beyond me. I've also been subpeanoaed to appear as a witness against her at her hearing.

I think my own case has a chance because 'driving at a safe speed' is ambiguous without hard data, hence the reason I posted, but as to the woman, I'm confused about why she wants to risk perjuring herself over a simple traffic citation.

It's more complicated than just an equation; it's more like collecting a bunch of evidence (tire types, skidmarks, type of damage, etc) and getting some kind of ballpark. Very involved work.

Especially without a lot of expert testimony there's no way it should be possible to prove you were guilty beyond a reasonable doubt of speeding when there were no witnesses, but if this was in Lycoming County things might not work that way; most of the judges there used to be cops from what I understand and sometimes don't exactly do things how the law and constitution say they should be done.

Sounds like the cop was a jerk on a power trip; I can't understand why else you would have been cited.

So you can't tell the speed from the weight of the car, length of skid and the angle of the skid? Hmm, that stinks. I would have thought you could get close with all that info.

Well, the problem is that the skid doesn't end on its own -- it ends with the remainder of the kinetic energy being absorbed by the vehicle's body and whatever it hits.

Ahhh, 'tis true.

I took a "transportation systems" class in HS.. I just found all the papers and stuff

most of the time was spent on crash-physics.

one of these days I'm going to scan and organize all my notes and stuff.. it's cool

Cool...do you think you could do it soon and email it to me?? please

the likelyhood of me doing anything "soon" is .... not good...

but I guess that depends on your definition of "soon"

Skid length would also be affected by tires and pavement type/condition. I'm good at estimating crash speeds, but it's just something you 'feel' along with relating it to all the crash testing I've seen. People who are unfamiliar with crashes usually overestimate speed FWIW, not realizing how little it takes to do extensive damage.

Best of luck to you. but I think your hosed.

Without hard evidence or a whitness you have no proof.

It pretty much comes down to your word against the Police officers, amd the judge is going to listen to the police officer. there is no such thing as innocent until proven guilty in traffic court.

Dispute it and they will find you guilty anyways. maybe deduct a little if your lucky.

Tleg93 wrote: I know there are experts who do this and there's been some question about how fast I was travelling at the time of my accident. I say it was 50 and the police say it was more. The only thing that's at stake is a $30 dollar ticket for drivin at a safe speed.

Well, I think don't you or I would be able to use the calculations properly. And, if this is really only for the $50 ticket and not a lawsuit worth 10's of thousands, then it's not worth it to hire an expert.

I say this: The burden of proof is on the cop (theoretically). So, the best you can do is hold his feet to the fire about proving it. He does have the burden of making some kind of argument, even if it's a crappy one. I'm sure will be qualitative like this: "I'm an expert because I've seen so many accidents. From the skid marks and damage I saw, he must have been going fast." Not very good proof, but that's the real world and the judge will probably buy it.

You don't have to call him a liar, you just have to cast doubt on the rock-solidness of his proof. The most important thing is to have *un-emotional, well-reasoned, factual* points to make.

Did the cop actually measure the skid marks? (No he didn't)

What about the damage makes the cop think it was such a high-speed impact? Cast doubt on whether he knows anything more than a superficial look at the damage. Ask him for documentation of a detailed inspection of damage inside and out.

What would make your accident situation unusual? Anything unusual might put this out of the cop's experience, and cast doubt on his ability to make a good estimate. Was it rainy? Is there any thing unique about your tires? Was the braking zone uphill or downhill?

Also, try to find counter examples... dunno if that's even possible. For a debate, examples > analysis. So, if you could find pictures of cars roughly the size of the ones in your accident, with roughly the same extent of damage, where the speeds are known, you could use that as a counter example that shoots holes in the cops proof.


It's like OJ, you don't need to prove your point, you just have to cast doubt on the cop's point..

Like I said, *un-emotional, well-reasoned, factual*. Don't be an upset asshole who is obviously a newb to this. The judge has already seen that a dozen times that morning and it pisses him off.

Redlined wrote:Best of luck to you. but I think your hosed.

Without hard evidence or a whitness you have no proof.

It pretty much comes down to your word against the Police officers, amd the judge is going to listen to the police officer. there is no such thing as innocent until proven guilty in traffic court.

Dispute it and they will find you guilty anyways. maybe deduct a little if your lucky.

I disagree, the offense is pretty ambiguous at best. It says Drive at a speed where you are able to maintain control of your vehicle. Well, the speed limit changes from 55 to 45 RIGHT THERE and in PA you have like over 100 ft to slow down after a speed change. That's also not to mention that the reason I lost control is because the lady pulled out right in front of me as I passed by, I didn't even hit my brakes because to do so would have meant that I would have hit her. The blackness of the skid marks isn't an indicator of how fast I was going, it could be an indicator of the type of rubber used or the fact that I was sliding without brakes. Anyway my man, this is a 30 fee...total. I'm just not about to plead guilty to my charge if she's pleading not guilty to her 'blocking a roadway' charge, it's just ridiculous.