Questions about CDR relating to AE and deployment.

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98tahoe
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First Name: Chrysta
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Questions about CDR relating to AE and deployment.

Post by 98tahoe »

First, a brief overview of my car accident. I was traveling 50 mph on a hilly, curvy highway on a clear sunny day. In a left bend I turn slightly and the rear end slides as if it hits a patch of ice. I make a 360, loose steering and cannot stop. I'm now going slightly uphill. I end up in the opposite lanes heading towards a guard rail. My tires are now turned to the right and suddenly "grab" the road. I'm now facing traffic and hit a vehicle almost head on. My air bags deploy and I was wearing my seatbelt, if that is relevant.

GM did a CDR on my 1998 Chevy Tahoe. Unfortunately, they are not helpful with explaining the information on it. I know there isn't a lot on it because I had an older model vehicle. But, these are a few of my questions:

The report states the time from algorithm enable to deployment command is 11.25 msec. Does this mean is took 11.25 msec from the time my car jerked to the right to crash? Is that what it records?

The recorded velocity change at 300 msec is -26.11. Do I understand correctly that I was going 26.11 mph at the POI?

Is there anything to indicate if my brakes were working? I do not have any skid marks except where the 360 was. The other car had skid marks where she hit the brakes and was spun into another lane after impact.

Thank you for your time!

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DPatrickRyan
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Re: Questions about CDR relating to AE and deployment.

Post by DPatrickRyan »

98tahoe wrote:The report states the time from algorithm enable to deployment command is 11.25 msec. Does this mean is took 11.25 msec from the time my car jerked to the right to crash? Is that what it records?
No. That is the time from the module "waking up" (i.e. the start of the collision) and commanding an air bag deployment. Collisions typically have a duration on the order of 100-150ms, about the duration of an eyeblink. Your ACM woke up and commanded a deplyment when the collision was about 10% complete.
98tahoe wrote:The recorded velocity change at 300 msec is -26.11. Do I understand correctly that I was going 26.11 mph at the POI?
No. The collision severity was 26.11mph - that is, your vehicle's speed changed by 26.11mph towards the rear. You could have been stationary and driven backwards at 26mph, or you could have come to a complete stop while hitting a wall at 26mph, and the module would have seen the same collision severity. All it cares about is whether you needed the air bag, not how fast you were going - your speed is only loosely related to the collision severity.
98tahoe wrote:Is there anything to indicate if my brakes were working?
No. If you wish to pursue this, you need an experienced collision investigator to review all available data, not just the download. This isn't the kind of thing you can do on your own.
D. Patrick Ryan, P.Eng. - Graham Ryan Consulting Ltd.
#34, 11410 - 27 Street SE Calgary, AB T2Z 3R6
Phone: (403) 290-1150 Fax: 290-0659 Cell: 651-8340

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98tahoe
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Re: Questions about CDR relating to AE and deployment.

Post by 98tahoe »

Thank you Patrick on the clarification. It makes a lot more sense to me now.

If it matters I had a typo (thanks auto correct). I stated I had "loose steering", it should be "loss steering".

Where do I find collision investigators? I thought that's what the state troopers did when they filled out the reports. (I, however, disagree with my report. The trooper didn't get statements other than mine until I asked him for them. Then he had to go get them, six weeks later. The report basically says I crossed the yellow line and hit car #1 despite my statement which was the only one he had at the time.)

So, my original question... A collision investigator? Someone outside law enforcement? Please advise.

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DPatrickRyan
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Re: Questions about CDR relating to AE and deployment.

Post by DPatrickRyan »

Depending on the crash severity and circumstances, the experience level of the LE member who attended your crash can vary widely - the trooper may or may not have had sufficient training to do a complete investigation, and policy might or might not allow him to do so. It's somewhat irrelevant, though: generally speaking, if you're unhappy with the LE investigation, you (or your insurer) is going to need to get someone else to do more work. You might want to consult http://expertdirectory.arcnetwork.com/ to find an expert in your area.
D. Patrick Ryan, P.Eng. - Graham Ryan Consulting Ltd.
#34, 11410 - 27 Street SE Calgary, AB T2Z 3R6
Phone: (403) 290-1150 Fax: 290-0659 Cell: 651-8340

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sd3225
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Re: Questions about CDR relating to AE and deployment.

Post by sd3225 »

Chrysta,

I agree with Mr. Ryan’s statement that the investigating officer may have been guided by policy on the “level” of the investigation based on the severity of the collision. In other words… there needs to be a balance on how much time is “spent” working on a property damage only collision vs a crash with severe injuries. Also, consider that the LE agency’s investigation is to determine if there has been a criminal statute violated for purposes of prosecution. Beyond that… the investigation does not always closely examine other issues that may surface on the civil side of the table, and is not required to.

When determining “primary cause” or whatever your particular state calls whoever is most at fault, it simply is a “who is more” at fault determination. It doesn't necessarily mean that person is 100% at fault, nor does it mean that the other party has no responsibility in the collision. So if crossing the double yellow lines or driving on the wrong side of the road is the primary cause of the crash… it doesn't mean that you intended to drive on the wrong side of the road. The report may make it sound like you were completely at fault for being on the wrong side of the road hence your disagreement with the report. Depending on what evidence was documented from the scene, there may be other ways to make some determinations, or at least help you understand the dynamics involved.

By working with a Collision Reconstruction Expert, you can examine possible surrounding issues that may or may not have been a contributing factor. With no other details regarding your crash that is about the best explanation I can provide you in a short answer.

Hope it helps some

Doug English
JDEAssociates
www.JDEAssociates.com

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98tahoe
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Re: Questions about CDR relating to AE and deployment.

Post by 98tahoe »

Thank you Patrick and Doug,

Both of your responses give me insight to why the report may have been filled out the way it was. I can see now it could have been for a number of reasons.

I am responsible for the accident as I crossed the center line. I realize the responsibility of the accident rests on my shoulders (and my insurance does too!) but still feel since the car lost steering and malfunctioned, I am not at fault.

This is why I followed up with GM. It wasn't a request from either insurance company. (I want to know what happened that had me unresponsive for almost five hours and broke the other woman's hip, ankle and arm.)

It sounds like my next move is a Collision Reconstruction Expert.

Many thanks for your input and information.

Chrysta

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