What is “Accident Reconstruction?”

Posted on September 27, 2021 by Daniel Vomhof

ACCIDENT: an unexpected usually sudden event that occurs without intent or volition

https://dictionary.findlaw.com/definition/accident.html

RECONSTRUCTION: an attempt to get a complete description of an event using the information available, or an attempt to repeat what happened during the event

https://dictionary.cambridge.org/us/dictionary/english/reconstruction

RECONSTRUCTION – 2b: a technical process by which scientific principles and techniques are applied to physical evidence in order to create an accurate reenactment or understanding of a past occurrence or event (such as an accident)

https://www.merriam-webster.com/dictionary/reconstruction

Depending upon who you ask, the Answer to the question of “What is Accident Reconstruction” will obtain slightly different answers. For instance –

  • Accident reconstruction is a branch of causation forensics which involves determining how and why an accident happened – accomplished first by correctly interpreting the clues left by the remaining physical evidence of the accident, then by reconstructing and studying the events preceding, during, and following the accident
    (https://www.facts-1.com/whatisaccidentreconstruction.htm)
  • Crash Reconstruction: The art and science of determining crash causes and events from known circumstances and available physical evidence.
    (https://www.crashforensics.com/crashreconstructionglossary.cfm)
  • An accident reconstruction is a scientific approach to solving the questions of how and why an accident occurred.
    (http://jda-inc.com/faq.htm)
  • Accident reconstruction is the process using scientific methodology to determine the circumstances, mechanics, and contributing factors associated with a collision.
    (https://www.plaintiffmagazine.com/recent-issues/item/auto-accident-reconstruction-the-basics-you-must-know)
  • Traffic collision reconstruction is the process of investigating, analyzing, and drawing conclusions about the causes and events during a vehicle collision. (https://www.sae.org/learn/content/c1728/)

At Expert Witness Services Inc, we believe that most of these definitions leave one important thing out. Yes, it is the consideration of the physical evidence using Math and Science. However, we believe that in addition to the application of Math and Science to the evidence, the Accident Reconstructionist must consider ALL of the evidence, not just the evidence he likes (and yes, witness statements are still evidence even though you cant see, feel, taste, smell, or measure them), and then be able to EXPLAIN why certain items are less reliable than others within the framework of the subject accident (collision, crash, incident …. whatever label you prefer), which items fit, which items dont, and WHY don’t they fit.

While we hope that you are safe on the roadways and do not need our services, unfortunately accidents DO happen. If you find yourself in an accident and need an accident reconstruction report, we ask that you call on our team at Expert Witness Services Inc.  To learn more about our services and what we can do for you in your specific incident, call us at 1-619-464-3477.

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Traffic Signals – Questions to Ask

Posted on October 25, 2021 by Daniel Vomhof

Many times the information that is available at a traffic signal controlled intersection is ignored. The only question(s) asked are – “Who had the green?”

Often times, the more appropriate questions are –

  • Who was moving as you approached the intersection?
  • Who was stopped?
  • What traffic moved immediately AFTER the collision occurred?

Armed with the answers to these questions, and the Traffic Signal Timing plan, a party with the appropriate education and experience can say ” based on the Traffic Signal Timing, and the movements described, Party B most likely had the green when this collision occurred.”

With his years of employment at the City of La Mesa, and subsequent years applying the knowledge gained at the City to Traffic Signal controlled intersection collisions, Mr. Vomhof has the knowledge and experience to interpret and apply the timing from most signal timing plans to a signal contolled collision.

While we hope that you never need his expertise, if you do, please consider us

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A Method to Calculate Speed From Crush

Posted on October 11, 2021 by Daniel Vomhof

Crush Factor Equation A question of interest in most collisions is “How fast was the car going?”

One method of beginning to determine the answer is to calculate speed from the crush to the vehicle. While there are several ways that this can be done, a method proposed by J. Stannard Baker and then refined by us at Expert Witness Services Inc. it to use what is commonly referred to as the “Speed from Skid” formula, but with a deceleration rate of 21 for a crushing vehicle as opposed to a more commonly seen 0.7-0.8 value for a skidding vehicle.

The benefits of this formula are several –

  1. Its easy to remember, since its a formula commonly used
  2. Its commonly used to calculate speed from braking, and so is familiar
  3. the calculation can be made quickly and with a basic calculatot, as opposed to a programmable calculator or computer.
  4. The speed arrived at has been generally reliable within a range of +/- 5 mph or less.

It is important to note that the speed calculated using this formula and a Crush Factor (CF)  of 21 is not, except under certain circumstances, a delta-v or impact speed. Rather, it is what we refer to as a Kinetic Energy Equivalent Speed (KEES) and others refer to as a Barrier Equivalent Speed (BES), Barrier Equivalent Velocity (BEV), Equivalent Barrier Speed (EBS), and other terms and acronyms of a similar style. All of these labels are indicating the speed calculated is the Energy it would take to subject the vehicle to the amount of damage that is seen and documented expressed as a speed.

For more reading on this, we invite you to read some of the publications found on our Software site at – http://www.4n6xprt.com/papers/

While we hope you never need our expertise, if you need a Accident Reconstruction for yourself, a loved one, or friend, please consider the staff at Expert Witness Services Inc in your search for a service provider.

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What is the difference between Accident Reporting vs. Investigation vs. Reconstruction

Posted on September 27, 2021 by Daniel Vomhof

ACCIDENT: an unexpected usually sudden event that occurs without intent or volition

RECONSTRUCTION: an attempt to get a complete description of an event using the information available, or an attempt to repeat what happened during the event

What is the difference between Accident Reporting vs. Investigation vs. Reconstruction? It is primarily a difference in effort and in detail.

  • CA_CHP555_sub6_2012_2 an incident report or accident report is a form that is filled out in order to record details of an unusual event that occurs. Often times in a vehicle accident it contains, who, where, what, and then some completed check boxes (see CHP Form 555 for an example, the typical “report” will often times not include a large diagram..)
  • Ideally, Accident investigations determine not only what happened, but also how and why. In practice, an Accident Investigation, specifically in automotive accidents, document (some) of the evidence and are taken to the point of who should receive a ticket, and who was (primarily) at fault.
  • A full Accident Reconstruction looks at not only
    • who was primarily at fault, but also at
      • what mitigating factors could have been employed by one or more of the parties to the incident,
      • what were (all the) contributions to the incident,
      • were one or more of the witnesses mistaken about what they saw/heard, and what indicates that they were mistaken,
      • what WASNT documented in the investigation, but should have been

Unless you have a serious collision with serious injury or death to one or more parties, often times the Law Enforcement agency will do one or more things –

  1. Rule it “non-reportable” in which case no report is filed
  2. “Report” the incident, with little or no documentation, or
  3. “Investigate” the incident, usually to the point of who should receive a ticket, but no further.

Very seldom are things taken further than this, primarily due to time, manpower, training (or lack thereof), interest (on the part of the officer(s)) and administrative pressure to “get the road open and get back on the road and do your job”. If you feel that what you have received is insufficient to answer the questions you need answered in your (potential) litigation matter, we at Expert Wtiness Services Inc may be able to help you. If your matter requires it, we can provide as complete a RECONSTRUCTION in your matter as is possible, given the material you have available to you. To learn more about our services and what we can do for you in your specific incident, call us at 1-619-464-3477.

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