September 30, 2015 by
In the middle of the night, police arrive at the scene of a collision to find two cars with significant damage stopped in the middle of the intersection. In the first car, which was struck on the passenger side, they find two female occupants seriously injured and unconscious. The ambulance crew is attending to them.
The second car has moderate frontal damage and is found unoccupied with the driver door wide open. They find one male sitting on the curb with an ice pack on his forehead, apparently faring better than the occupants of the other car. The male shows clear signs of alcohol impairment.
He tells the police that the empty car is his, but that he was a passenger in his own car when the collision occurred. The driver was a good Samaritan that he had just met at the local pub who had kindly offered to give him a ride home given the amount of alcohol he had consumed. He states that this person unfortunately fled the scene immediately after the collision before he had a chance to ask him what his name was.
There is nobody else around to confirm or challenge this statement. Was he really a passenger in his own car or was he driving while being impaired?
Another typical case could involve a vehicle occupied by several individuals travelling at highway speed that starts drifting sideways and then hits the gravel shoulder. In an attempt to recover, the driver steers hard to the left and then to the right, sending the vehicle into yaw before going off road and rolling over several times in the ditch, while ejecting some of the occupants along the way. After the dust has settled, the surviving occupants may not remember who was driving, or the lone survivor and owner of the vehicle claims that he was not the driver.
In cases like these, driver identification becomes a critical issue and forensic engineers specializing in accident reconstruction and bodily injuries can provide assistance. Our work in such instances is based partly upon the post-crash physical evidence relating to the occupants, including the injuries sustained and the resting positions of the occupants, and partly on circumstantial evidence as conveyed by the surviving occupants and potential witnesses.
We also review the physical evidence documented at the collision site (e.g., tire marks) and the damage sustained by the vehicles to understand how the collision occurred and how the occupants moved inside the car, and even outside if they were ejected. In an ideal situation, we will be given the chance to inspect the interior of the vehicle to document any evidence of contact between the occupants and surfaces inside the car, evidence of seat belt use or non-use, as well as the driver seat position. Any organic material or fabric transferred onto a surface can be collected after its location inside the vehicle has been documented. The underlying goal of such verifications is to be able to assess who was sitting where at the time of the accident and, especially, who was in the driver’s seat, by matching the injuries with the evidence of occupant contact inside the vehicle including:
1. Matching seat belt bruises with evidence of seat belt use;
2. Matching any organic transfer from the occupants to exposed surfaces inside of the car;
3. Matching any fabric transfer from the occupant’s clothing to exposed surfaces inside of the car.
Other parameters can also be documented for that purpose. For example, we may find that the driver seat position is only consistent with the size of one or a limited number of occupants. In cases of severe frontal collisions, such as head-on collisions, shoe prints may be visible on the pedals.
The electronic crash data may also help us confirm the presence of passengers in the vehicles and their approximate size. it may also contain information about the speed of the vehicle and driver actions such as braking, accelerating and steering, which can then be compared to the circumstantial information relayed by the occupant and witnesses
To sum up, if you need to know who was behind the wheel at the time of a collision, give your accident reconstruction expert a phone call. Your expert may be able to answer that question.
Jean-François Goulet, P. Eng., is a mechanical engineer with CEP Forensic Engineering Inc. specializing in accident reconstruction. He has been in the road vehicle accident reconstruction industry for 10 years. He is also a member of the Association of Professional Engineers in Ontario and Quebec, the Association of Professional Engineers & Geoscientists of BC (APEGBC) and the Society of Automotive Engineers (SAE). Jean-François Goulet can be reached at firstname.lastname@example.org.