How accurate are police investigations of speed after an accident?

Hi all,
Just curious as to how accurate a traffic officer's investigation is in terms of vehicle speed after an accident?

 

Oh there HAS to be a backstory to this....

 

Need story first.

 

I LOVE this shit! I read headlines on TW like this everyday...CNN does have squat on us!

Oh do tell...

 

im guessin op was doin 90 mph, 144 km/h

 

I want to see pics of his truck...recent pics!

 

Well dude the police officer is going to take everything into account, he/she needs to come to a conclusion and then write the accident report based upon what information was given to them and make there own assessment of what they think happened. so once it has been written there is no changing it.

But more detail is needed to give you a correct response.. so spill it

 

Just depends on all the factors involved. Actually kind of easy to find a minimum speed if there is a yaw mark left on the road(when a car starts to rotate. Back tires start to track outside the front ones). Just find the friction of the tires and roadway with a drag sled. The find the radius and then put it into the formula. Sounds complicated but really not that bad. But most officers probably guess, unless its a bad wreck.

 

Hahah you guys are funny man. Well, basically I was driving, somehow took my eyes off the road, next thing I know I'm crashing into not one, but TWO light poles. I swear to this day I remember only doing 55 mph. (Speed limit was 50 mph.) The traffic officer wrote me a citation for 70 mph in a 50 mph.

What's so difficult about the situation is that I don't really doubt the officer's investigation but I seriously do not remember doing 70 and the fastest I drive would be 5 over the limit. Always.

Well that's the story.

Oh and the brakes were not even touched until after I went off the road, I guess I panicked and didn't even know what the hell was happening so I never hit them. I'm not sure if the officer took this into account.

 

S=3.86√r(f+-e)

S=speed @beginning of yaw
R=radius of yaw mark
f=coefficient of friction
e=superelevation or bank of roadway

Here is the formula for a spinout. Maybe this will help you. Sorry, I love reconstruction. My thing.

 

From my one experience with this, I would have to say they are horribley inaccurate. Buddy, hit a pole at 15mph (while doing a burnout), cops said he was doing 50+ becuse of the marks on the ground... which were burnout marks, not brake marks...

 

This is what I'm afraid of. The whole situation was odd because they barely questioned me about the incident and they allowed two witnesses to leave without a statement.

 

I had a very serious accident back in 2006. I fell asleep and drifted lanes went off the road flipped it twice and rolled it 4 times, since I was asleep I never hit the brakes and there were no yaw marks. Anyways cops did their thing reconstructed the accident and came to the conclusion I was doing 90 mph (posted speed is 45mph). I denied this and said I was doing 45mph. It was later proved that I was indeed doing 45mph, the computer in my vehicle recorded it since I had my cruise control set. So I got off with no ticket. The whole cop reconstruction was complete bullshit!

 

Good, very good.

 

Damn man, that's crazy. Being off by 45 mph is a pretty huge margin, can't believe they were off by that much. What kind of car did you have when you crashed? My cruise control wasn't set so I probably can't use that, unless it's recorded anyway.

 

I think you're missing the d for distance....

 

I never actually spunout. I basically went onto the curb in a straight path and completely took out two light poles, parallel to the road. Hope that made sense.

 

I had a 2000 Chevy S-10. I didn't think that truck could keep record of it but hey I didn't get a ticket so I guess it could. The cops were real eager to give me a ticket since I had a really bad driving record (speeding tickets) that the only accident I have ever been in. So I am glad it could and really glad I had set my cruise.