HELP! If YOU or someone you know has been in a crash!

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HELP! If YOU or someone you know has been in a crash!

Post by brian »

Q: Have YOU or someone you know been involved in an crash aka accident and need HELP?
A: In many cases over the years we have assisted individuals involved in crashes/accidents to help them sort out the facts and circumstances of the accident/collision.
The initial and main assistance is to instruct them to try to accumulate all the information on the accident including police reports, measurements, photographs, witness statements, etc. This is extremely important!
The field of accident/collision reconstruction includes specialized applications of the fundamental laws of physics which require information/evidence about the collision;
  • tire marks,
  • damage to the vehicles,
  • scene information, etc.
Please read our general introduction Accident Reconstruction Techniques and Accuracy
With this information any competent accident/collision reconstructionist should be able to perform a preliminary evaluation to ascertain initial impressions and some form of preliminary opinions.
Questions like:
  • What happened?
  • What were the approximate speeds?
  • What were the circumstances which led to the collision/accident?
  • Was the accident avoidable?
  • Who caused the accident?
Some of these questions can be answered quickly, others may take time to fully investigate and draw proper conclusions.
When we assist people involved in collisions, we try to emphasize that the police are not their enemy! Many people involved in collisions come to us with blood in their eye because they think that the police/prosecutor “are out to get them”!).
That is not the case in most circumstances.
  • With an informal initial impression and preliminary opinion from a qualified expert in accident reconstructionI a subsequent discussion with the police investigator about the particulars of the accident/collision may resolve things (Over the years it has happened on many occasions). Particularly if it is something perhaps the police have overlooked and/or misinterpreted. That is how we as accident/collision investigators and reconstructionists are supposed to do our job!
    Many, if not all, of the 'pro bono' cases we have done have been resolved without our having to travel or incur expenses except for spending a little of our time assisting those involved in an accident with understanding the circumstances of the accident.
    Sometimes we write a report/affidavit to assist them in their defense. Sometimes we have suggested that they use the information we have provided to them and contact a local expert for additional assistance.

We have often thought about forming some form of an ‘Innocence Project’ type association to be used to assist folks ‘before the verdict’ (since the current ‘Innocence Project' is for folks already convicted). We just haven’t found the time and/or funds to move forward on that idea.
  • The average person involved in a collision/accident does not have adequate resources when compared to the police/prosecutors offices. It takes considerable effort to sift through all the information and evidence in accidents/collisions. The creation of a 3rd party objective panel to review the evidence and police work 'before the verdict' would be justified and beneficial to avoid unwarranted prosecution. I believe in Europe this is how cases are handled. The Judge hires two independent accident reconstructionists/investigators. They come to conclusions. If they agree. case closed. If not, a 3rd party is brought in to settle the dispute.
    If YOU have been in an collision/accident and need assistance, please email us at or contact someone in your area who does collision reconstruction. Be prepared with the circumstances of your situation including the police report, if possible, and perhaps you can get some needed assistance.
Contact information is:
Question? Comment? Please email Also see the McHenry Forum Index
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Steve Stockinger

Re: HELP! If YOU or someone you know has been in a crash!

Post by Steve Stockinger »

New here and seeing stuff for the first time.
This is pretty good stuff.
Steve Stockinger
retired detective

Site Admin
Posts: 1366
Joined: Thu Jun 18, 2009 12:37 pm

Re: HELP! If YOU or someone you know has been in a crash!

Post by MSI »

In another forum someone posted up a description of a crash in Europe and included the question:
  • "how many % may an investigator be wrong with pc-crash?"
The following is our response and anyone seeking an experts help in a collision may benefit from this list:
  • Where in Europe are you located? Are there not any local experts who can help?
    If you provide where you are located perhaps someone on this forum knows someone in that area.

    The following is a list which if you find a local expert you should provide to them as it contains ideas for proper evaluation of the situation:
    Also, if you provide more information, some of the many experts on this forum might be able to assist you:
    • post up pictures of exterior damage to the vehicles
    • you mentioned drone pics? post those
    • any police report? crash diagrams? post those
    • you also mentioned "how many % may an investigator be wrong with pc-crash?"
      • did the police or some expert in your case use pc-crash?
        • if so, first the answer to that question is 'it depends'.
          pc-crash is a momentum based simulation solution and so subject to momentum limitations and simplifying assumptions
          In several cases we have been able to make a singular change in inputs (the point and angle of momentum exchange') and change the results of a pc-crash simulation used as the basis for an opinion by an expert to the opposite opinion
          One example was a 'who's on the wrong side of the road' crash, see below
    You should obtain the inputs and the diagrams from any pc-crash simulation used in your case.
    You should also demand you get the input file in electronic form for ANY simulation/animation so an expert can review all inputs and rerun the simulation.
    Some inputs may not be included in the run summary
    • In most courts in the USA the inputs for any simulation or animation must be provided in electronic form.
      This allows the other side to rerun the simulation to be sure all inputs are produced so they can be checked
      • weights? specifications? tire properties? values for friction? friction zones? terrain slopes? source of terrain information?
      • proper dimensions for evidence location and ability to compare that to the simulation/animation?
      • if animation, it is physically possible and does it obey Newton's Laws?
        • the electronic inputs provide the changes in movement so the speeds/approx accelerations can be calculated
      • And do the graphics/video created match the inputs provided?
        • we have cases where inputs (in paper form) and graphics/video provided looked OK however once we obtained in electronic form we found that the printed paper inputs where different than the electronic inputs and did NOT produce the video/graphics! (and so the case settled shortly thereafter!
here are some links with additional information: Here is a comparison of two pc-crash runs in a case where an expert used pc-crash as the basis for the expert option of who was on the wrong side of the road.
We demonstrated that pc-crash did NOT prove who was on the wrong side of the road:
The experts pc-crash reconstruction was as follows:
wrong side 2.png
wrong side 2.png (464.91 KiB) Viewed 180 times
Putting the vehicle in proper lane and a making a minor change in the pc-crash 'point of momentum exchange' could have proven the vehicle was in its proper lane!:
wrong side 1.png
wrong side 1.png (530.54 KiB) Viewed 180 times
NOTE: we have posted this up as a separate forum topic with additional information:
Question? Comment? Please email Also see the McHenry Forum Index
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(c) McHenry Software, Inc ALL Rights Reserved.

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