Case study: Accident reconstructionist determines fault, brings peace of mind to victim’s family
When the Event Data Recorder (EDR)
fails in a vehicle involved in a serious accident resulting in death, the only
way to accurately determine contributing factors is by using the services of a
skilled accident reconstructionist.
Oftentimes, witness statements and information obtained at the time of
the accident can be helpful, but incomplete. They can be tempered by memory loss caused by injury, or
colored by relationship to other involved parties. When a loss is so serious that it involves death, it is
imperative that the investigation into the cause uses evidence that is unbiased,
and mathematical in nature.
On a dark night, on a lit roadway
clear of debris, a small vehicle (vehicle #1) stopped at a stop sign at an
intersection, and then proceeded to turn left onto the southbound section of
the main road. A larger vehicle
(vehicle #2) driving southbound on the main road, did not see vehicle #1 until
it was too late. Driver of vehicle
#2 slammed on their breaks, but was unable to avoid vehicle #1. The impact sent
vehicle #1 spinning, and vehicle #2 off the roadway. Vehicle #1 sustained significant damage to the passenger
side quarter panel, including the rear seat compartment. The front passenger was ejected from
the vehicle and the rear passenger had to be cut out. All three occupants were hospitalized for their injuries,
with the rear passenger ultimately succumbing to their injuries. Vehicle #2 sustained damage to the
front bumper, grill, and passenger side front tire. Both the driver and passenger were also hospitalized. Due to the serious nature of the
injuries sustained, a detailed investigation was undertaken to determine the
proximate cause of the loss.
Preston Forchion, II (ACTAR #2480)
was brought on in concert with other law enforcement professionals to collect
evidence and ultimately complete an analysis of data, both collected and
computed, to determine the contributing factors in this loss.
The investigation started with
statements from the drivers, passengers and witnesses. The driver of vehicle #1 stated that
they turned left onto the main road, then heard a passenger utter “watch out”,
and felt the vehicle spinning. The
surviving passenger was able to provide the series of events leading up to the
accident, but ultimately could not remember any major details of the loss
itself. Driver of vehicle #2
recalled seeing vehicle #1 entering the intersection, and then feeling the airbag
deployment. The passenger of this
vehicle stated vehicle #1 did not stop at the posted stop sign, but offered no
further details. Additionally,
through extensive investigation, one disinterested third party was located who
was witness to the crash, driving behind vehicle #2 southbound on the main
road. According to this party,
vehicle #1 pulled in front of vehicle #2, causing the driver of vehicle #2 to
brake unsuccessfully to avoid impact.
They stated they believed the driver of vehicle #2 to be going the speed
limit, as they were. Mr. Forchion
additionally determined there were no extenuating distractions, i.e. cellular
phone use or drugs and alcohol.
With the statements providing
conflicting versions of the events causing the loss, it became imperative that
an exhaustive investigation be completed using data from the EDRs in both
vehicles, and calculations completed by Mr. Forchion that relied on his
extensive experience as an accident reconstructionist. He began by returning to the crash site
to laser the scene. Additionally,
he conducted skid tests using a Vericom to determine the average coefficient of
friction (COF) to assist with the reconstruction, which he determined to be
.75. After obtaining search
warrants for each of the vehicles, there was an attempt to image the EDR and
Powertrain Control Modules (PCM) in both.
This was only successful for vehicle #2. The inconclusive image of the EDR for vehicle #1 was
possibly due to the loss or catastrophic failure. Per the EDR in vehicle #2, it was traveling at a speed of 60
mph five seconds before the loss, 57 mph at the moment the brake switch
indicator activated, and the impact speed was 36 mph. While this information indicated
that vehicle #2 was speeding, and the speed may have contributed to the loss, a
detective from the prosecutor’s office made it clear that they believed summons
should not be issued based on EDR alone.
They preferred an EDR report to be examined by a reconstructionist such
as Mr. Forchion who has been trained in EDR report analysis. Additionally, the lack of conclusive
data from the EDR in vehicle #1 would make his analysis and computations even
more important in finalizing the determination of contributing factors.
Using the information gleaned from
the initial investigation, the general sequence of events was determined. Vehicle #1 entered the intersection
into the path of oncoming vehicle #2.
Vehicle #2 then applied the brakes, and attempted to steer away from
vehicle #1, but was ultimately unsuccessful. Mr. Forchion was able to determine this by examining vehicle
#2 position at its final resting point, and a skid mark on the road from the
damaged front passenger side tire.
The point of impact (POI) was evidenced by a gouge mark noted in the
center of the south bound lane of the main road. The rotation of vehicle #1 was evidenced by tire marks. Using the COF he had calculated, along
with the scale diagram measurements obtained by lasering the scene, Mr.
Forchion was able to reconstruct the crash scene. Additionally, he again returned to the loss site to compute
the point of first possible perception, which he determined to be 391
feet. Moving forward, he
calculated the Point of Actual Perception (PAP) to be 251.49 feet using both data
from the EDR for vehicle #2, and his own computations from his work
reconstructing the accident scene.
After determining these important
values, he was then able to make determinations regarding the minimum post
impact speeds using his scale diagram, and general information obtained from
Expert AutoStats. He then
calculated the approach and departure angles for both vehicles. After doing so, he was able to compute
the impact speeds of both vehicles involved, and the results he obtained were
within 2% of the speeds recorded by the EDR (where the normal margin of error
is +/- 4%). Ultimately, this meant
that vehicle #2 was traveling at 57 mph, with an impact speed of 35.36
mph. Although he did not have EDR
data from vehicle #1, it was easy for someone with the extensive experience in
reconstruction like Mr. Forchion to determine that vehicle #1 experienced a
“hard” crash pulse due to size of vehicle and relative impact speeds.
With all of the information and
data he was able to collect and compute, he moved on to determine if the fact
that vehicle #2 speeding was a contributing factor to this loss. To do so, he computed the PAP at the
posted speed limit, which he determined to be 136.46 feet. From this location, to the POI would
have been 122.51 feet. Using his
COF, he determined it would have taken vehicle #2 90 feet to come to a complete
stop. This meant, all other
factors remaining the same, that vehicle #2 would have been able to come to a
complete stop 32 feet prior to the POI if they had been traveling at the posted
speed limit.
The last piece of the puzzle was to
determine if vehicle #1 had stopped at the stop sign as the driver claimed in
their statement. To do so, he
computed the acceleration rate based on the previously determined impact speed,
applying the distance from the stop sign to the POI. Using a time/distance chart for each vehicle, Mr. Forchion
was able to determine that vehicle #1 did in fact stop at the stop sign posted
at the intersection.
Ultimately, using the evidence
obtained from the scene, statements of involved parties and witnesses, and his
extensive research and computations based on his abilities as a SME, Mr.
Forchion was able to determine the most signification contributing factors to
this loss. First, driver of
vehicle #1’s failure to yield the right of way. Secondly, driver of vehicle #1’s inattention. But most interestingly, and perhaps
most important when determining fault, the third most significant contributing
factor was the unsafe speed of vehicle #2.
Why is the speed of vehicle #2
significant? When determining
fault as an insurance company, or representing your client as a bodily injury
attorney, the sliding scale of percentages used becomes incredibly important.
When a loss results in the unfortunate and untimely passing of a person involved,
it is paramount that you have concrete evidence to back up your
determination.
In a situation where there are
serious injuries rendering involved parties unable to give complete statements,
or equipment malfunctions removing large portions of accident data, you must
turn to a third party. In this
case, Mr. Forchion’s investigation refuted a witness statement regarding speed
of vehicle #2, and determined that vehicle #1 had in fact stopped at the posted
stop sign.
Accident reconstructionists determine
contributing factors in losses with incomplete data, by adding their expertise. He was able to compute important values
like PAP, POI, and MPH, thanks in no small part to his years of training and on
the job experience. His abilities
make him an asset to the investigation, and to prosecutors, insurance companies,
and bodily injury attorneys. Those
who hire him to provide concrete evidence as to the proximate cause of loss in
accidents are able to have the peace of mind that the investigation and results
will hold weight in negotiations, and hold up in court. And that peace of mind is important for
everyone involved.
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ACTAR is an independent accrediting organization recognized
in the United States and Canada. It offers an independent credentialing
examination that objectively assesses a candidate’s comprehension and
application of minimum training standards of a forensic specialist in the field
of motor vehicle accident investigation and reconstruction.