An "accident" is defined as "an unexpected and undesirable event". Accident reconstruction is a branch of causation forensics which involves determining how and why an accident happened - accomplished first by correctly interpreting the clues left by the remaining physical evidence of the accident, then by reconstructing and studying the events preceding, during, and following the accident.



A peculiarity of this profession is that accident reconstructions are methodically worked backwards, time-wise - from the end results back to the beginning sequence of events.

All kinds of accidents are investigated through reconstruction methodology — plane crashes, crane failures, bridge collapses, vehicular collisions, etc.

Reconstructions of traffic collisions, specifically, typically involve determining the factors which contributed to the cause and severity of the collision, such as excessive speed, poor visibility, a defective tire, the failure of an occupant to wear a safety belt, or the disregard of traffic control devices.

Don't the police already do this?
A police officer's duty after an accident is to document basic event information (mainly to satisfy a statistical need by state and federal governments), try to determine fault for his/her report (usually by interviewing drivers and witnesses to find out if any traffic laws have been violated), call for care for the injured, and to maintain safety around an accident scene.

Very few traffic collisions are technically investigated by the police if no fatalities are involved. In most official traffic accident reports, the details necessary for an accurate reconstruction of the collision are scarce.

The arrow in the photo at left indicates abrasion on the "D" ring of a three point seatbelt, which was produced by the heavy loading of the occupant's body acting on the webbing (lower left) at impact.

The abrasion is a conclusive indication that the seat's occupant was belted during the collision.

Officers trained in accident reconstruction are rare, and as a result police can, and do, unintentionally overlook fraud and deception and other factual anomalies at an accident scene because they can't reconcile the differences between the physical evidence and the conflicting statements of witnesses. The driver with the most believable story often prevails. Errors aren't uncommon.

Evidence such as tiremarks and furrows in the dirt can quickly disappear. The chances are excellent that, not only will these important clues not have been measured and documented, they won't even be mentioned in the police report.

Who are accident reconstructionists?
Accident reconstructionists in the private sector are independent forensic generalists and specialists, some retired or moonlighting police officers with special training, and others technically-trained like engineers and physicists who have specialized in related fields and who have the necessary training and experience in accident reconstruction.

In the past few years many engineering firms have ventured into the technical forensics of fire and crash investigation because of the fields' newly found popularity. Though many of these firms have been around for years engaged in various engineering projects, their actual expertise in fires and crashes may actually be quite limited. In causation forensics, experience really does matter - and FACTS has focused on this field full-time for over a quarter century.

Accident reconstructionists are typically retained by insurance companies and attorneys. They're also sometimes hired directly by private individuals who've been involved in a serious collision but were not satisfied with the way their insurance company, attorney, or police handled their case.

What do vehicular accident reconstructionists do?
In vehicular issues, accident reconstructionists deal with a lot of factors, depending on the case. They answer questions such as: What events contributed to the cause of the collision? Was the driver speeding and just how fast was he going? Could the driver have avoided the collision? Was the passenger wearing a seat belt? Who was really driving the vehicle? Was the fatal collision an "accident", or was it really a suicide? Were the brakes maintained properly and did this contribute to the cause? Why didn't the driver see the other car? Was a vehicle driven at night without its lights on? Which driver's story is the more truthful?

In many instances, an experienced accident reconstructionist can uncover other important aspects of a crash which have been completely missed or overlooked by others.

Multiple factors may be considered in one collision. When two cars collide at a busy intersection at night, for example, the reconstructionist may need to determine not only who had the right-of-way, but also whether a vehicle was being driven without its lights on, the speeds of the vehicles, and whether the occupants were wearing their seatbelts.

"Skidmarks" (typically called "tire marks" by reconstructionists) are measured and analyzed, the scene is photographed, and the damages on the vehicles are thoroughly examined for evidence of collision force direction and severity.

An accident is often caused by the actions of more than one driver, like when a drunk driver pulls out in front of another driver who's speeding. This becomes a case of "comparative negligence", where it becomes a matter of who was "more" at fault.

If the bulb hasn't been too badly damaged, it's often possible to determine whether a light was functioning and ON at the moment of impact.

In the rear signal bulb at left, the arrow indicates the bulb's tungsten filament, which was twisted and distorted from a severe and fatal rear impact.

The distortion is conclusive evidence of incandescence, since the filament becomes ductile and stretchable only when heated. A cold filament typically breaks without significant stretching during such an impact, a condition known as "cold shock".

The accident reconstructionist must also deal with fraudulent accidents, usually involving what we at FACTS refer to as "rear-ender-fender-benders". Sometimes the collisions are staged, but more often the fraud simply involves seizing the opportunity of a real collision to claim non-existent or exaggerated injuries.

Fraudulent claims such as these have long been a problem for insurance companies. In South Florida especially, it's been reported that these claims are estimated to be 50-80% of the total auto injury claims filed. In addition to individuals taking advantage of impacts to fake or exaggerate injuries, organized groups have also moved into insurance fraud.

According to insurance industry reports, insurance fraud of all types costs Floridians over $1 billion annually and drives rates up approximately $246 per household.

Accident reconstruction involves accidents of many flavors, not just vehicular mishaps. For more on this area, visit the Product Liability page.

For photos of crash tests and other crashes from FACTS files, click on the Links & Articles link icon at the top of this page.

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