Essentials: Biomechanical Engineering in Low-Speed Rear End Collisions

September 10, 2009

  • December 19, 2010 at 9:38 am
    kelly says:
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    Wow is this wrong. I was stopped and rear-ended by another vehicle travelling at least 20 mph. I have whiplash, bruised shoulder, it crunched my entire spine with resultant nerve pain, disclocated two ribs, broke one and crunched my right ankle (on the brake pedal). You folks really need to look at reality because this article is patently wrong.

    • May 17, 2011 at 10:45 am
      Jim says:
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      you clearly misunderstood the article. it is not talking about a 20 mph impact. The studies that are cited have a max impact speed of about 7mph. it even says low speed in the title! 20 mph is not considered low speed and the scientific community is well aware of the impacts of a high speed (yes 20mph is considered high speed.)
      this article is not incorrect, it is spot on, you ma’am are incorrect though

      • December 31, 2012 at 12:28 am
        bob says:
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        almost everyone in the reconstruction business and biomechanics business recognizes that we start seeing complaints of spinal symptoms at a delta V of five.

        But if we look at the general public, they are not as well informed about the necessary precautions for self-protection in vehicles. People frequently don’t have the head restraints adjusted properly. Human volunteer testing doesn’t replicate this. It my experience it can actually occur a little before then, especially when you have people sitting out of position or have their head turned or have a preexisting condition that makes them more vulnerable to injury.

        That’s the problem with insurance companies. They see everybody as statistics and only worry about their bottom line.

  • February 23, 2013 at 12:32 am
    Greg says:
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    This article is a joke and probably funded by the insurance industry. I know a 29 yr old girl (27 at time of ‘minor’ rear end accident that only had minor pain and settle case for few hundred bucks. Today she has cervical surgury scheduled, which I’ve recommended against but she is tired of the pain. And yes this all started from a rear end accident that caused $1,300 in damage. People’s lives are changed forever by minor accidents….but you turn the victim into some fraud…..sham on you.

  • March 11, 2015 at 10:44 am
    Mike G. says:
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    While its encouraging to see people questioning the science (some of which is plain wrong)in the article, my experience as a trial lawyer is that the typical juror buys into this and more often than not find in favor of the at fault drivers and award plaintiffs $0. There are competing views for example Delta V and acceleration of the occupant will be higher than that of the vehicle not lower. Occupant acceleration is often 2.5 times that of the car. Also people too often assume that no damage mean no injury. What they fail to consider is that due to pressure from the insurance industry, auto manufacturers are building increasing stiff vehicles to withstand impacts up to 5-10 mph with no damage thereby reducing insurance claims for damage. The insurance industry then exploits these improvements and claims the crash was not significant enough to cause injury. Then they deny the claim or refuse to pay all of the claimant’s medical treatment practically forcing them to court. Its very difficult to try this type of case because the cost of depositions, court mandated mediations or arbitrations, doctors testimony etc can quickly out run the value of the case.

  • March 18, 2015 at 3:14 pm
    Kristin Stefanelli says:
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    Can someone assist me?

    About a year ago, I was involved in a low speed rear end collision, I was in a Dodge Journey the vehicle which struck me was a 25,000 lb Penske truck. My head was turned as I was watching for my opportunity to make a right turn, and the collision caused $3500 in damages to my vehicle.

    My claims adjuster’s offer was less than my medical bills alone, he states he cannot relate all my treatment to this “low speed” collision.

    I had soft tissue injuries significant enough to cause nausea and vomiting, and I treated very conservatively with PT and Chiropractic care. I continue to have residual pain, I don’t feel like I will ever fully recover.

    Is there some force of impact formula or study for which I can use to illustrate the dynamics of this large vehicle’s force?

    • May 27, 2015 at 4:46 pm
      Chris says:
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      Kristin,

      There is a way to determine how much impact your suffered. Although, it will take either you, or an attorney to hire an accident reconstructionist, preferably with biomechanical engineering experience and also preferably certified through ACTAR. Unfortunately, those people that hold the deciding factor (jury) tend to believe these guys with their calculations, models, and articles, more than experienced medical practitioners (who also study and research this stuff, but also take into account several other factors, such as your unawareness of the impending impact, your head being turned, etc.) Also, unfortunately, the insurance adjuster will say whatever he wants and the only thing that will change his mind is a jury verdict. These adjusters offer up their completely inexperienced, uneducated, personal opinion simply to keep the claim payout low (so it reflects positively on their performance) and then make adjustments to their offer based on their belief of a possible law suit outcome.

      BTW, your nausea and vomiting was more likely caused by a mild traumatic brain injury (MTBI) than from the pain from your other injuries. (Yes, it can happen even if you did not hit your head… though you probably did hit your head on the head restraint when rear-ended by a Penske truck!) That should have been documented and explored. If it was, the insurance adjustor would most likely have had a different offer for you.

      Also, I am surprised that the adjuster said this was a low-speed collision. They normally (incorrectly) attribute the speed to the amount (dollar amount) of damage to your car. Normally, $3500 would indicate a moderate-high impact. They normally view anything under $1500 as “low”…. go figure… What would the same exact physical damage cost for a 1994 Corolla compared to a 2015 Mercedes? Obviously it would cost significantly more for the Mercedes… so does that mean that the Mercedes was “high-impact” while the Corolla was “low-impact”????

      This is their game. They make they’re own rules, change them mid-way through and never let you know anything about any of it.

  • September 5, 2016 at 1:31 am
    allen triplett says:
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    What a great Ponzi scheme insurance is!
    After my ’98 forester was rear ended (I was almost stopped) by a lowered nissan(65 mph by at fault’s admission), my left shoulder hurt, and an old neck injury hurt like heck.
    MRI showed a torn rotator cuff. Literally one week previously I had finished a three month job involving a lot of upper body exertion, with no ill affects.I lost almost 200k of lost wages alone(I was looking at over $40.00 an hour, with another$23.00 in benefits) when i couldn’t accept dispatch to a job with a ton of overtime, and a 2-year duration. My attorney secured policy limits from the at fault, but now we may need accident reconstruction, and scholarly studies by an engineer to collect on my under insured policy! I see your post was from last year. How did you come out?
    Thanks,
    Al

  • September 30, 2017 at 5:35 pm
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    Foreman and Croft found 57% of their whiplash cases had low back pain, LBP. Braaf and Rosner found LBP in 42% or 141 patients after whiplash. Hohl found LBP in 35% of his cases. Magnusson reported 48% of his research group to have LBP following whiplash. Gargan and Bannister reported 32% of their group having LBP and an additional 10% with late manifestation. This is just a sliver of the research available for review. The problem with engineers is that they are not doctors, they don’t examine the patient, and they are not experts in occupant kinematics and there injurious affects on the body. The occupant isn’t attached to the seat, when the initial impact occurs in a rear impact crash, the seat back moves forward and contacts the thoracic and lumbar spine. The thoracic curve (kyphosis) and the lower back curve (lordosis) are forced into a straightened position because of the intense loading forces upon them. This causes tension, stretching and compression of the discs and joints of the spine. In addition to this there is a ramping effect caused by the rear of the vehicle being pushed downward upon impact. In the re-entery phase of the crash the seat back acts as a diving board and flings the torso forward. The spooling mechanism of the restraint system has load limiters and allows for forward movement of the torso and many times the locking spool doesn’t engage so the occupants torso can move forward a great deal. The hips are anchored by the lap belt and that allows forward movement of the pelvis and loads it into the webbing of the restraint, which causes a great deal of tension and traction on the pelvis and lower back which can cause disc herniation’s, facet injuries, or muscle injury. It is ridiculous to state that injuries to the low back can not occur in rear impact collisions when in fact there is mountains of research which refutes these claims.

  • February 27, 2018 at 3:27 am
    Joseph Awad says:
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    Michael,
    I would bet $1,000 that you are a practitioner of Chiropractic, which I respect, but not the “know it all attitude” and incorrect statement about the “engineers”. If you read the article you should have noticed that the engineers are biomechanical engineers. If you know anything, you should know better than to suggest that they don’t know anything about occupant kinematics. That was just plain ignorant. The engineers do not treat or diagnose, so there input is not medical testimony. What they are qualified to address is injury causation, and yes, many are more qualified than the medical doctors. The problem is that both medical and chiropractic doctors, like you, are willing to opine that every one of the individual’s problems are from the “accident” when neither has the background in all of the various injury mechanisms nor in how to quantify the severity of the impact. The basis for your opinion is because the plaintiff said they didn’t have the problem before the collision. You should have your license yanked because you don’t know what the hell you are talking about.
    Ramping is only minutely the result of a vehicle’s rear being pushed down but much more the result of the progressive angle induced to the seatback while loading it, causing the occupant to “ramp up”. Also, your quick assessment of the ineffectiveness of seatbelts couldn’t be more incorrect. Load limiters are not going to be an issue in “Low speed rear end collisions” now are they? No,they are not. How much do you really know about the retractor mechanism or statistically how often they fail to work and why? You are critical of the movement allowed by the restraint system and clearly do not understand the importance of that movement and the “stretching of the webbing”. Do you know what the result would be if that movement and stretching were designed out of the restraint? I’ll bet you’d like rigid seatbacks as well?
    You are such a hypocrite with your bashing of the insurance industry and attempt to disqualify the engineer. I wonder what impact it would have on your practice if you had the balls to tell the truth about the likelihood of injury in “Low speed rear end impacts”. It would probably make it difficult to convince your patient that they need 4 different types of treatment 4 times a week for oh, I don’t know… let’s call it 4 months; if you were not such a pro-injury, pro-plaintiff advocate. You really should probably just stick to “adjustments” and quit trying to impress us with the chiro-vocab and by quoting studies authored by your other pro-injury, pro-plaintiff colleagues.



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