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.