Newton’s Laws of Motion

F=Force, M=Mass, A=Acceleration

First Law: A body will remain at rest or continue to move in a straight line at a constant speed unless acted upon by an unbalanced force, F.

Second Law: If an unbalanced force, F, acts upon a body, its center of mass will accelerate in the direction of the force. The acceleration, a, is proportional to the force, F, and the constant of proportionality, m, is called the mass of the body. F=MA

Third Law: For every force acting on a body, there is an equal and opposite force acting on something else. (For every action there is an equal and opposite reaction)

Speed Change

The best single measure of the severity of a collision is the speed change that the vehicle undergoes during the brief time interval of the collision. The speed change is the magnitude of the difference between the pre-impact and post-impact velocities of the vehicle. It occurs in a split second. In fact, a typical car collision is over in 0.12 of a second. This means that an occupant’s body and head could be jerked from 0 to 10 mph in a spilt second. Breaking it down this way makes it clear why a low speed collision can cause moderate to severe neck and back injury and pain.

The concept of the collision speed change is especially important in low speed collisions because the amount that a vehicle rebounds in a collision that results in little or no damage is significant.

In most cases, the only thing that matters to the occupant is the speed difference between his or her body and the vehicle interior.

Types of Impacts in Auto Accidents

Rear impacts

Frontal impacts

Lateral Impacts

Sideswipes

Within each type of impact the accident reconstruction expert will try to determine:

1. Vehicle Dynamics (the motion of bodies under the action of forces.)
2. Occupant Kinematics (the motion of objects without reference to the forces that cause the motion.)

Vehicle Dynamics & Occupant Kinematics

Questions to occupants & witnesses to determine Vehicle Dynamics & Occupant Kinematics:

1. Vehicle Dynamics:

• Was your vehicle at rest?
• If not, what was its speed?
• Did your vehicle move as a result of the impact?
• How far?
• Were you behind another vehicle?
• How far?
• Did you hit the vehicle in front?
• Was the vehicle in gear?
• Which gear?
• Were the brakes applied?
• How hard?
• What was the speed of the other vehicle when it struck your vehicle?

2. Occupant Kinematics:

• What was your height and weight at the time of the collision?
• Where was the seat positioned?
• How was the seat back adjusted?
• Was the seat belt used?
• What type of seat belt was used and how was it adjusted?
• Where was the head restraint adjusted?
• What was your posture in the seat?
• Where were you looking?
• Did you know the impact was coming?
• Describe what happened to your body at impact.
• Did any portion of your body contact the vehicle interior?

The exact questions will vary from case to case, but at the end, there should be a complete description of the motion of the vehicle and occupants during the collision. 

Rear Impacts

The risk of injury in any particular incident will be dependent on many factors including:

• Collision speed change,
• Vehicle structural characteristics,
• Seat and head restraint dynamic characteristics,
• Position of head restraints,
• Use of seat belts,
• Occupant age,
• Occupant sex,
• Occupant stature,
• Occupant posture,
• Predisposition to injury,
• Knowledge of impending impact.

NOTE- cost to repair the vehicle is not listed as a factor. 

Injury Mechanisms in Rear Impacts

1. Hyperextension/Hyper-flexion Injury-“Whiplash”
2. Occupant’s body is accelerated forward,
3. The head gets left behind because of its inertia,
4. The neck extends backward beyond its normal limits,
5. Forces developed in the neck accelerate the head forward,
6. The neck overshoots its normal position, and
7. The neck will then flex forward.
8. Differential Rebound Injury
   1. Occupant’s torso rebounds forward from the seat prior to the head because of seat geometry and different seat and head restraint stiffness characteristics,
   2. The neck extends backwards even if there is a head restraint positioned behind the head.

1. Tension/Compression Injury -“Ball and Chain”

Compressive and tensile (pressed & stretched) loading can develop in the cervical spine even though the overall motion of the head and neck are within normal limits, i.e. no hyperextension/hyper-flexion (whiplash).

1. Spinal Canal Pressure Pulse Injury

Rapid head and neck motion, even if within normal limits, can cause pressure increases that may be damaging to nerves in the neck.

1. Cervical Facet Joint Injury

The joints in the neck that allow flexibility are a common source of pain in rear impact claims. 

Accident Reconstruction Testing & Research Has determined:

1. Symptoms such as neck pain and headaches begin to be reported in low speed rear impacts at speed changes as low as 2½ mph.
2. Research reveals a significant prevalence of neck injury in rear impacts with speed changes of 6 to 9 mph.
3. Some vehicles can withstand a collision speed change of up to 8 or 9 mph and remain essentially undamaged. At this level of impact, the occupant’s acceleration is far from trivial and the collision is well above the threshold level at which symptoms such as neck pain and headache are reported.
4. A “no-damage” collision can have a speed change of 1 mph or 8 mph. It is essential to know at which end of the range the speed change lies. Risk of injury may be virtually non-existent at the lower end, but at the upper end there is a strong potential for injury.

Vehicle repair costs are not a factor in determining the severity of an injury in a rear impact claim.

• To find out how MartinLaw, PLLC and attorney Chuck Martin will handle your car accident case please visit the car accident page.

• Our client was driving with her two boys ages 6 and 4 in the back in carseats down a busy thoroughfare in Bellevue when a vehicle suddenly pulled out from a shopping mall exit directly in front of them.
• She was traveling about 25 to 30 mph and had no time to stop before crashing head-on into the other vehicle.
• This was a severe impact as the airbags deployed and the vehicles were totaled.
• She began having persistent neck and back pain and stiffness. She sought treatment with her primary care provider.
• She was diagnosed with cervical and lumbar strain and referred for physical and massage therapy.
• The initial evaluation noted that she was unable to carry her other young son age 1½ for longer than 5 minutes.
• It was also noted that she experienced left hip pain when walking and generalized aching pain across the scapulae and cervical musculature with tenderness and spasms from L3-L5. Every time she took a step with her left leg it caused a sharp pain in her left hip.
• Additionally, she was having difficulty performing her job duties in her language translation business.
• She continued her treatment for approximately 5 months during which time she suffered pain as a result of this accident.
• The boys suffered mental distress as a result of the accident. A traumatic event like this is very disturbing to a young child.
• Due to the boys’ ongoing symptoms and fear of riding in a car, or that the car was driving too fast, their mom sought assistance from a child psychologist.
• Both boys were diagnosed with Post Traumatic Stress Disorder. The treatment consisted of the mother going to the psychologist to learn techniques to help the boys get passed their PTSD symptoms. It was felt that they were too young to get direct treatment and that going to a psychologist’s office would traumatize them further.
• The 6 year old’s PTSD was manifested with anxiety, irritability and hypervigilance. He is constantly telling his mother or father that the vehicle is going too fast even when going slow.
• The 4 year old’s PTSD was manfested with anxiety, irratibility, withdrawal, nightmares and difficulty sleeping.
• The clients had a very limited amount of medical treatment.

In spite of the limited medical treatment, the law firm of MartinLaw PLLC was successful in negotiating substantial 5-figure settlements.

• To find out how MartinLaw, PLLC and attorney Chuck Martin will handle your car accident case please visit the car accident page.

• A driving instructor, who had a student in the vehicle with him, failed to yield right of way at 20^th Avenue and Yesler, and turned left into oncoming traffic crashing head-on into our client’s vehicle.
• Our client hit his head on the steering wheel causing a concussion and blurred vision.
• Due to headaches and neck and lower back pain he went to the emergency room at Swedish Medical Center where it was noted that he had contusions on his forehead and left knee, acute cervical strain, lower back pain and a closed head injury.
• He was given CT scans of the head and cervical spine which revealed head atrophy and degenerative disc disease in the cervical spine.
• He was prescribed pain medications (Norco) and muscle relaxants (Robaxin) and discharged with diagnoses of closed head injury, acute cervical strain and acute knee contusion. He was advised to see his primary care doctor without delay.
• He did visit his primary care doctor who prescribed physical therapy.
• The physical therapy records note degenerative disc disease in his cervical spine, osteophyte formation in the lumbar spine, disc space narrowing at L2-3, lumbar facet arthropathy, anterolisthesis and excessive lumbar lordosis. These are medical conditions that develop over time and are not immediately caused by a traumatic injury. They would be considered preexisting conditions.
• The physical therapist observed guarded walking and excessive eye movements to avoid cervical rotation and continually using his arms for support. Pain level is 8 out of 10. Also noted, pain can cause migraines.
• He was unable to continue physical therapy as his wife had a stroke and he is her caregiver.

Despite that fact that our client’s medical treatment was intermittent and of short duration, and his primary diagnoses were for preexisting conditions, Chuck Martin was able to negotiate a substantial five figure settlement.

• To find out how MartinLaw, PLLC and attorney Chuck Martin will handle your car accident case please visit the car accident page.

• Our client, a lady in her mid-forties, was walking down James Street with her fiance in downtown Seattle heading for the Ferry Teminal with the intention of taking a scenic ferry ride across Puget Sound to Bremerton. Suddenly a large truck came careening down the hill, slammed into several parked cars causing one of the cars  to burst into flames. Several other cars then caught fire.
• Our client ran down the hill to get away from the truck and the flames. She lost her balance and slammed into a nearby building.
• A television news report on this accident was shown on KOMO 4 news.
• Although mentally distraught, she decided to make the planned ferry trip to Bremerton, hoping that it would help calm her mental state. It is about a three hour round-trip. By the time she got back to Seattle she was in severe pain. She was also experiencing nausea, anxiety, vomiting, crying and an asthma attack.
• She went to the emergency room at Northwest Medical Center. She was treated for her back pain with a narcotic injection and advised to return to the ER if she experienced increased pain.
• The next day she did experience increased pain and returned to the Northwest Medical Center ER. She was again treated for her low back pain and instructed to follow-up with her primary care doctor.
• She returned to the ER at Northwest Medical Center with sharp lower back pain radiating down her legs and reporting that it was painful to walk. The doctor suspected myofascial pain or possible herniated disc. She was discharged with pain medication.
• She reported to the ER at Highland Medical Center. Her pain level was 7/10. Radiology reports indicate disc narrowing at L2-3, anterior osteophyte at L3, arterolisthesis at L2, sclerosis and hypertrophy at L3-4, L4-5 and L5-S1.
• She was back in the ER at Northwest Medical Center a few weeks later for severe low back pain. This time she was referred to a neurosurgeon for evaluation for possible low back surgery.
• She was finally able to get an appointment with her primary care doctor who noted leg weakness and shooting pains into the legs. She also reports that when she coughs it feels like she’s been “tazed”, pain shoots across her hips, her legs feel frozen and give out and pain shoots down both thighs. She was referred her for physical therapy.
• Physical therapy started  about eight weeks after the accident. Her pain level was noted at 7/10. She continued with physical therapy for three months. The PT notes document the continuation of her pain, muscle spasms and radiculopathy throughout this period.
• Although she had pre-existing lower back conditions, the records make it clear that these conditions were exacerbated by the accident.
• She also had preexisting anxiety problems which were exacerbated by this accident with PTSD symptoms.
• The case proved difficult as it appeared our client never had any physical contact with the truck that caused the accident, or any other object projected by the truck. We were finally able to determine through video footage and medical reports that she was struck on the ankle by an object from one of the exploding vehicles.
• Another problem was the fact that nearly all of her diagnoses preexisted the accident.  However, we were able to show that the symptoms were exacerbated by the accident.
• Despite the difficulties with he case we were able to recover a substantial five figure settlement for our client.
• To find out how MartinLaw, PLLC and attorney Chuck Martin will handle your car accident case please visit the car accident page.