Every year, according to the Centers for Disease Control and Prevention, 2 million people are hurt and 32,000 people die because of car accidents on American roads. Causes of these accidents include driving while distracted, failing to wear a seatbelt, and drinking or taking drugs before hitting the road.
People often report feelings of panic or confusion during accidents because of injuries they sustain or the abruptness of the collision. As a result, the different parties often deliver contrasting accounts of what happened in the crash. Law enforcement personnel and insurance companies must work together to resolve conflicting testimonies before they can assign liability for the accident.
Sometimes, determining who is responsible for a collision is simple, especially if the liable party admits to causing the accident. For example, if one car collides with the back bumper of another, the person driving the rear car is at fault. In other cases, assigning liability is much more complicated, and that’s where an accident reconstruction expert comes into play.
What Does Accident Reconstruction Involve?
Accident reconstruction is an analytical process that experts use to determine how an accident happened. Sometimes, experts have help from security recordings or images taken by speeding cameras. More frequently, they have to rely on the location of the cars after the accident has taken place to conduct their jobs.
Before accident reconstruction analysis can take place, the reconstruction team looks at visual clues. These include the presence or absence of turn signals, the cars’ position relative to stop signs or stop lights, and the severity of the damage. They also look for factors outside of the cars that could have caused the accident, such as black ice or broken traffic signals. Ideally, this step takes place before any of the evidence gets removed.
For the reconstruction to be effective, the team must gather more complicated data. To figure out the drivers’ speed, the team measures any skid marks. They also note the cars’ final positions to understand the angles at which the drivers were steering. If the tires are still intact, they may use an air gauge to calculate their pressure in pounds per square inch.
What Does an Accident Reconstruction Expert Do?
Accident reconstruction experts’ duties vary slightly from job to job. Generally, though, these professionals look through all the documented evidence, use it to determine how the drivers approached the collision site, and model different ways that the crash could have occurred.
Analyze Documents
If possible, an accident reconstruction expert helps collect data at the crash site. If he or she is not present at the scene, official documentation of the incident is crucial. For example, if a bystander called the police after the accident, the local law enforcement office should have a file containing pertinent details:
- Time of the accident
- Location of the collision
- Photographic evidence
- Eyewitness testimonies
- Driver testimonies
- Insurance information
- Speeding camera footage
If anyone was injured in the crash, medical records are often helpful for an accident reconstructionist. For example, if the drivers claim that they were driving slowly but a passenger has severe whiplash, the cars were probably moving at high speeds. The presence of medical records also makes accident reconstructionists’ work more urgent; determining fault allows the victims to handle their medical bills.
Determine Speed, Force, and Other Key Values
Calculations are a key part of accident reconstruction experts’ jobs, especially if they don’t have reliable data on the drivers’ speeds. If skid marks are present, the University of Connecticut recommends using this formula to determine the original speed: S=55√(cl). First, determine how much friction occurred between the tires and the road, and multiply that coefficient (c) by the length in feet of the biggest skid mark (l). Take the square root of this value and multiple it by 55 to determine the car’s speed in miles per hour.
If the reconstruction team does not know the friction coefficient (c in the previous formula), they must also calculate that. According to the University of Regina’s Pacific Institute for the Mathematical Sciences, this formula applies: f=F/W. Here, f represents the friction coefficient, F represents how much force gravity was exerting during the crash, and W represents the weight of the tire in pounds. Normal values for the friction coefficient on wet roads are around 0.4, a figure that jumps to 0.7 for wet ones.
Look at the Cars’ Black Boxes
Most American cars manufactured in the 1990s or later have a special feature called a black box or event data recorder. This system collects information about how drivers use their brakes, whether they buckle their seatbelts, how quickly they travel, and whether they use their turn signals. Police officers, other law enforcement personnel, and accident reconstruction experts are authorized to access black box data after a crash, although they must obtain warrants in some cases.
Occasionally, black boxes are too seriously damaged for their data to be accessible. Usually, though, they help an accident reconstruction expert identify exactly how the drivers were behaving when they crashed.
Put Together the Findings
After collecting all this data, accident reconstruction experts begin to put together the results. They may use a 3D printer to help people visualize what happened, or they may simply write up their findings. These include the person who is at fault in the accident, why the accident happened, and whether any factors such as broken brake lights, wet roads, or forgotten turn signals played a role.
What Are Some Different Types of Accident Reconstruction?
Accident reconstruction can take place when any type of car or vessel gets in an accident, but the process is slightly different for trucks, motorcycles, commercial vehicles, semis, and boats.
Truck Accident Reconstruction
If a truck is involved in a crash, its size compared to a standard car complicates all calculations. For example, trucks driving on the highway must travel for up to 525 feet before stopping completely, but a standard car needs only 315 feet. Because the stop time is so much bigger, standard formulas that rely on skid mark length no longer apply.
The same is true of trucks’ increased weight. They are more likely to cause severe damage even at low speeds, especially if the other car is a normal passenger vehicle. Thankfully, most trucks have black boxes, so accident reconstruction experts can get their speed data there.
Motorcycle Reconstruction
Crashes involving motorcycles are especially challenging. Because of their small frames, it’s easier for motorcycles to get so damaged that they are hard to analyze, particularly on the highway. Skid mark formulas still apply, but the friction coefficients are usually much lower because their tires weigh less.
Accident reconstruction experts must also look out for dangerous behaviors that are not possible with standard passenger vehicles. Motorcyclists tend to weave through traffic, especially during heavy traffic, a phenomenon called lane splitting. California has legalized lane splitting, but all other states still forbid it. As a result, if an accident reconstruction expert determines that a motorcyclist was splitting the lane during an accident, that driver is likely to lose his or her case in court.
Commercial Vehicle Accident Reconstruction
Like trucks, commercial vehicles tend to weigh more than standard cars. Their heavy cargo loads may make it even harder for drivers to stop. Additionally, some commercial vehicles have decreased visibility because their back windows are covered by the goods they’re transporting.
In terms of documentation, commercial vehicle collision reconstruction is more complicated than crashes involving individuals. Even if the person operating the vehicle is technically at fault in the crash, the entity liable for the accident may be the vehicle’s owner, the person’s employer, or the company as a whole. The driver is responsible for the crash if he or she broke the law, in which case black box data is helpful. If the commercial vehicle was poorly designed or improperly maintained, the employer, company, or even the manufacturer is liable.
Semi Accident Reconstruction
Semis are Class 7 or Class 8 trucks. Class 7 semis have one frame and at least four axles, while Class 8 semis have two frames and at most four axles. They are much bigger than standard pickup trucks and are likely to be commercial vehicles, so the same concerns about determining liability apply.
Boat Accident Reconstruction
Sometimes, an accident reconstruction expert will also offer maritime services. These reconstructions are much harder than standard crashes because calculating speed or angles from skid marks is impossible. To work in boat accident reconstruction, the expert must understand all the laws for safe navigating.
For example, sailboats and other vessels without motors always have the right of way over powered vessels. Additionally, because there is more room on the water than on the highway, boats that are moving towards each other should each shift to the right so that their left sides slide past each other. Determining whether a vessel obeyed right of way laws often requires reliance on eyewitness testimony rather than on speeding camera footage. Analysis of where the boats collided can help, though.
Forensic Accident Reconstruction
Whenever accident reconstruction takes place because of a criminal or civil court case, it counts as forensic accident reconstruction. The same procedures apply, but law enforcement personnel such as investigators are more heavily involved. Also, the accident reconstruction expert will probably have to present his or her findings in the courtroom.
How Do the Police Reconstruct an Accident?
After collecting their data, police officers work backward to determine how an accident happened. They may come up with several potential ways that the accident began. Then, they can choose from three main ways to represent their reconstruction.
1. 3D Models
3D models are helpful in both the process of reconstructing an accident and the presentation of that reconstruction. The police make several scale models of the highway or intersection where the crash occurred. Then, they use models of the cars and any obstacles involved to demonstrate what happened in several steps. It’s critical that they also include information about factors that are hard to represent in dioramas, such as wet roads or cell phone usage.
2. Written Reports
If the accident is easy to visualize, the police may not bother with a 3D model. Instead, they write up their findings in a report that includes photographic evidence and citations from the case file. Written reports may also accompany 3D models if the case is very complicated.
3. Software Modeling Systems
Several software programs are helpful for testing theories about how a crash occurred, and they can also create animations that serve as models in court. Usually, these programs rely on computer-aided design technology. Popular brands include Virtual CRASH, PC-CRASH, and Pam Crash FEM.
What Is the Purpose of Traffic Accident Reconstruction?
Traffic accident reconstruction helps the people involved in a crash resolve their disagreements, and it can also help prevent future accidents.
Determining Fault for Insurance
Even if neither party will admit to fault in an accident, one insurance company has to assume liability. In cases that are ambiguous, both companies may refuse liability until they have more evidence. When this happens, accident reconstruction allows the insurance companies to see exactly what their clients were doing when the accident happened.
Determining Fault for Court Cases
Court cases do not result from every car accident. If one party fled the scene directly after the collision, the accident may count as a hit-and-run incident, so the other party could press criminal charges. Reckless speeding, negligence, and driving without proper licensing may also be grounds for a court case. Generally, disputes over fault in accidents only lead to court cases if passengers were seriously injured or killed.
An accident reconstruction expert can serve as a key witness in these cases. He or she can present software simulations, 3D models, black box reports, and other analysis results as evidence.
Learning How To Prevent Future Accidents
Accident reconstruction efforts conclude when the team identifies the points at which the drivers could have avoided the accident. This could be the moment when a motorcyclist left his or her lane or when a truck driver pulled out his or her cell phone to check a text.
As accident reconstructionists identify the different ways that crashes happen, they are also collecting useful information on how state and local government officials can prevent similar accidents. For example, perhaps multiple traffic accident reconstructions reveal that a curve in the road severely reduces visibility. The local transportation officials could repaint the lane lines, add reflective markers along the curve, and put up signs warning drivers to reduce their speeds.
What Is Crash and Accident Reconstruction Analysis?
Crash and accident reconstruction analysis takes place after reconstruction experts have collected their data but before they have created their final models or reports. Sometimes, their initial findings do not provide enough information to create a conclusive reconstruction. Perhaps one car’s tires were punctured in the accident, so it is impossible to precisely calculate their weight at the time of the crash. Perhaps the accident reconstruction expert cannot determine exactly how wet the road was during the accident, making it hard to determine the coefficient of friction.
These and similar scenarios require reconstruction teams to conduct extensive analysis using software programs. They run multiple simulations using different possible values until the simulated accident resembles the real one. Once they’ve tested their theories, they must reexamine their evidence to ensure that their simulated model accounts for all the facts.
If you’re wondering, “Where can I find an accident reconstruction expert near me?”, reach out to our team at Mecanica Corporation. Our experts have over 30 years of experience in forensic accident reconstruction and are qualified to work with incidents involving both private and commercial vehicles. Email us at info@mecanicorp.com or use our website to find the phone number of the office closest to you.
Sources:
- https://www.cdc.gov/vitalsigns/motor-vehicle-safety/index.html
- http://mathcentral.uregina.ca/beyond/articles/rcmp/accident.html
- https://www.forbes.com/sites/marinamedvin/2019/01/08/your-vehicle-black-box-a-witness-against-you-in-court-2/?sh=278402c631c5https://www.hg.org/legal-articles/stopping-distances-for-commercial-vehicles-28265#:~:text=A%20normal%20passenger%20vehicle%20such,recognizing%20the%20need%20to%20stop
- https://worldpopulationreview.com/state-rankings/states-where-lane-splitting-is-legal
- https://www.roads.maryland.gov/OPPEN/vehicle_Class.pdf