Car accidents are fast, violent, and generally confusing both to people involved and eyewitnesses. Piecing together what happened after the fact used to be next to impossible, but now, thanks to advances in forensics, this is not the case. Forensic investigators can use a variety of tools and physical evidence to put together a clear picture of what happened during a car accident.
UNDERSTANDING THE PHYSICS OF AN ACCIDENT
A forensic investigator’s understanding of what happened during a car crash is based on collision physics. The key variables are kinetic energy and momentum. When two cars collide, kinetic energy isn’t conserved, but total momentum is. By measuring the masses of the cars and the distance that they slid together, and accounting for drag forces, investigators can find total momentum. If one car was stopped, it is easy to calculate how quickly the other car was traveling. If both cars were in motion, total momentum still gives investigators a starting point.
MAKING TIME-DISTANCE CALCULATIONS
Next, investigators can work with simple time-distance calculations. Distance is the multiple of speed and time. So, for instance, if investigators know how fast the vehicle was initially traveling, and they have a figure for the average human reaction time, they can calculate how far the vehicle traveled while the driver was reacting to the situation. More complicated formulas can help investigators determine the total braking distance and time.
ANALYZING PHYSICAL EVIDENCE LIKE SKID MARKS
Measuring the length of skid marks is another way that investigators can determine how fast the vehicles were traveling. When the skid distance, the drag factor due to road surface friction, and the braking efficiency are determined, the minimum speed of a car as it started skidding can be found. The appearance of the skid mark also tells investigators whether a car was braking, accelerating, or sliding. Therefore, skid marks can indicate who might be at fault for driving recklessly.
Debris left in the road can also be a telling piece of evidence. Debris can help indicate where the collision actually occurred, which is useful because the involved cars will often be cleared off the road by the time investigators arrive.
ANALYZING PHOTOGRAPHS OF THE SCENE
Photographic evidence can be crucial, since the accident scene can’t be blocked off and analyzed indefinitely, and the vehicles involved will often be moved or towed. Good documentation of the accident scene allows for a thorough analysis that can be handled even by investigators who weren’t on the scene. Additionally, photographs are often a key piece of evidence if the accident has to be settled in court.
LOOKING AT THE INVOLVED VEHICLES AND TOTAL DAMAGE
Forensic investigators also research the manufacturer specifications of the vehicles involved to learn about things like collision ratings and the braking system. Once specifics about the vehicles are known, the damage to each vehicle can shed more light on the accident. For instance, if the force that a bumper can withstand is known, and the bumper is crushed, investigators can find the minimum force of the collision.
PRODUCING SPECIFIC FIGURES FOR SPEED AND FORCE
When all the evidence has been collected, investigators can determine the force of the collision, as well as the speed the cars were traveling before and during the collision. This is crucial in determining if one driver was at fault for ignoring the speed limit or otherwise driving recklessly.
FORENSIC EVIDENCE MAKES A SIGNIFICANT DIFFERENCE
Forensic analysis of car accidents can provide many insights that firsthand and eyewitness accounts do not. Furthermore, forensic analysis is much more difficult to dispute in court. Thanks to recent advances in technique and improvements in measuring equipment, a careful forensic crash scene analysis can be pivotal in deciding the outcome of legal cases involving car accidents.