Although accident reconstruction is primarily used in lawsuits as well as for safety improvements, it also has some uses in other industries.
For example, fire departments can use accident reconstruction to conduct arson investigations and deconstruct the path of a damaging fire, as well as designing evacuation plans to help promote fire safety.
Additionally, insurance companies also make use of accident reconstruction software when drafting a root cause analysis. Many police departments deliver information reports from analysis to insurance companies, but insurance adjusters often require a check on the information they receive. An insurance adjuster can quickly piece together a reconstruction of an accident to help inform their decisions and file accurate claims.
Accident reconstruction teams also research, analyze, and test in order to get an understanding of vehicle safety systems and how each component is designed and engineered to manage collision forces and ensure occupant protection. After such research and analysis, reconstruction engineers frequently publish technical publications suggesting improvements or appropriate modifications for vehicle manufacturers.
Seat belt system evaluations often begin with an inspection of an accident where the seat belt system was stressed. Results of analysis provide an understanding of collision forces and related load signatures to various components. Seat belt system evaluations include the retractor assemblies’ collision performance assessment involving such components as web-grabbers, load limiters and pretensioners. Evaluations of seat belt buckle assemblies include how the buckle component performs during a collision and everyday use by occupants. Seat belt webbing can also provide details regarding occupant use and restraint system performance.
Airbags with complex sensing systems and algorithm designs in a variety of collision modes are also analyzed. System performance evaluations are conducted to determine whether the subject collision forces were sufficient for airbag deployment, whether deployment occurred timely, and the effectiveness of the airbag in protecting the occupant in the given collision.
Investigations of vehicle safety systems such as airbags and seat belt systems can provide conclusions of safety system performance that can then be relayed through reports and publications.
I found an interesting article describing how accident reconstruction was pivotal in a court case in Pennsylvania on March 6, 2012:
Recently, a Michigan man was formally charged with a moving violation that caused the death of an Amish woman and her horse…
Accident reconstruction teams determined the car was traveling at a rate of 63 mph despite the speed limit being posted at 55 mph. This turned out to be the deciding factor in whether or not to charge the man with a misdemeanor or a felony.
This is a clear example of the importance of accident reconstruction in resolving legal disputes. This is just one of many court cases that have been resolved through the help of accident reconstruction engineers. This is because accident reconstruction software can provide people on the stand with an animation to help show speed, position and other key information about the vehicles involved.
After the analysis is completed, reconstruction engineers typically present their findings through a 3D animation, such as the one above. Animations are used to demonstrate, through visual aid, the underlying analysis made by the expert engineer. The animation depicts the accident sequence in a video format so that juries, or any others unfamiliar with the process, can easily understand the engineer’s conclusions. Animations are usually realistic in obeying the laws of physics and accurate in depicting exactly what happened. However, the reliability and source of the demonstration should always be questioned since the technology is so easily manipulated.
Video Source: http://www.youtube.com/watch?v=Dt53sjfCEJw
When sufficient data cannot be gathered from inspection, accident reconstruction firms frequently conduct their own tests and accurate duplicated crashes to gain more information. More commonly, however, these test are performed to supplement and confirm earlier analysis and research.
To run a test, vehicles of similar if not the same system design and structure are used to ensure accurate results. If the test purpose of the test is to evalutate the effectiveness of a particular component, identical components are found so the recreation is as similar to the original accident as possible. Anthropomorphic test devices, called ATDs, are often used for assessing injury potential and effectiveness of safety installations. Testing is furthermore thoroughly captured by high speed, real time and miniature video cameras. It is important to note that these tests may not always be direct recreations, sometimes the engineering team just wants to evaluate how the vehicle and its components react to an impact.
Example tests used by real-life reconstruction firms include: full scale vehicle impact drop testing (aka “dropping the box”), component shock table testing, restraint deployments including out-of-position occupant injury potential evaluation, seat belt deployments, seat belt retractor performance evaluation, and component strength testing. All of the above tests are performed to measure forces, motion, accelrations, strain on dummy occupants, pressure, and heat.
Picture of a vehicle impact drop test (Source: http://www.dreng.com/testing.htm) :
Before the inspection process is started and quantitative analysis can be performed, accident reconstruction engineers (or a team of them) may visit the crash site themselves. Based on their initial qualitative observations, rudementary conjectures can be made. Naturally, the more experienced the engineer, the more capable they are of making accurate conjectures.
For my research, I will investigate some common examples of qualitative data from which conclusions can easily be drawn. For example, scratch patterns on a vehicle typically indicate a rollover and give clues about the vehicle’s path after it rolled over. Furthermore, multiple scratches on the vehicle’s exterior can indicate several rollovers and if the scratches cross in a pattern, the engineer could possibly determine the sequence of the rolls.
Many times accident reconstruction engineers want to know whether or not the driver was braking at the time of the collision. An experienced engineer could examine the filament in the brake lights at the accident site to predict if the driver was braking or not. Filaments in brake lights tend to elongate under quick negative accelerations during an accident.
Source: Terry McNamara (my mentor), employee of Design Research Engineering.
The principles of math, physics, and engineering can be applied in accident reconstruction to predict the causation and nature of the collision.
In a previous post I referred to a method of site examination called inspection. Significant data and mathematical quantities can be gathered from the digital models created after inspection.
For example, the data when compared to an undamaged vehicle can provide data regarding the displacement, or crush, that occurred during the accident. Moreover, using publicly available crash test data, a vehicle’s stiffness during a front, side, or rear impact can be found. By comparing the displacement calculated in inspection with the stiffness data found, you can determine the energy dissipated during the collision. Using physics laws of energy, you can then calculate the vehicles instantaneous velocity the moment before impact. The CAD software used in inspection can usually come with functionality of and perform most of the calculations needed for analysis. The interpretation of the data, however, is the job of the engineer.
Aside from inspection, which only provides data about the vehicle, photographs of the accident can provide information about the accident scene.
For example, how far the vehicle(s) traveled, along with whether they were moving straight, twisting, braking, or rolling over, can be applied to calculations of momentum. Furthermore, visual cues such as tread mark distance can facilitate the extremely important calculations of velocity.
As stated previously, most of the mathematical and physics quantities found and analyzed work to calculate a vehicle’s speed/velocity. Speed, as well as momentum, is a very key quantity to have when identifying causation of the collision (i.e. the driver was exceeding the speed limit for road conditions, etc.).
Source: Terry McNamara (my mentor), employee of Design Research Engineering.
The discipline of accident reconstruciton has a brief history. However, it has gained much evolvement and progression in recent decades. The field gained official recognition in 1985 when the National Highway Traffic Safety Administration (NHTSA) provided a grant to fund field research as well as the first national guidelines for the analysis training in the field of traffic accident reconstruction.
Furthermore, a group of accident reconstruction engineers, police officers, educators and attorneys created the Minimum Training Criteria for Police Traffic Accident Reconstructionists to help standardize the field and outline its goals. This led to the formation of The Accreditation Commission for Traffic Accident Reconstruction (ACTAR) in 1991 to maintain the recognition of industry standards developed by the NHTSA. Even today, ACTAR continues to regulate and set new standards in the discipline of accident reconstruction. Paralleling the field, software used in accident reconstruction also has developed and improved significantly in the last two decades, allowing for more advanced and detailed analysis.
In its short history as a recognized field, accident reconstruction has been applied and contributed to the development of many common safety practices and advances. For example, the use of comprehensive accident reporting has identified patterns in seatbelt use, helmet use for motorcyclists, the need for improved driver training, etc. Furthermore, attorneys have applied accident reconstruction reports to court cases to help identify blame (as stated in previous post about applications).
During the previous summer, I attended a family reunion in Wisconsin. At this family reunion, my uncle, who is my mentor, showed me a slideshow about his work in accident reconstruction. After he showed me this, I became very interested in accident reconstruction and its applications.
Similarly, last year I took a course at Westwood called IED that introduced me to computer-aided design and modeling. This further sparked my interest towards the topic, since reconstruction is analyzed digitally with computer models.
This interest has prompted my research question: What is accident reconstruction and how can it be used to solve real-world problems?