Accident and incident reconstruction has become a significant component of courtroom testimony. Using multiple skills, engineers examine evidence that could affect a defendant in a positive or negative way. Forensic engineer and regional manager Timothy Cheek, P.E., at DELTA |v| Forensic Engineering, Charlotte Regional Office, summed it up: “The basic process of accident reconstruction involves collecting the evidence; studying the evidence like pieces of a puzzle to put back together; and, once we have a solution to the puzzle, presenting our findings in a way that is understandable to others. These are the same aspects that are involved in many fields of engineering: collecting information, studying that information to solve a problem, and presenting the findings to others.”
This is a growing field for engineers who investigate and reconstruct vehicle accidents by getting as much information as possible to make a scientific analysis of the data and formulating it into a report that will be used in court testimony. The work consists of rigorous documentation, testing, modeling, and simulation of accidents and covers all types of vehicles from cars and trucks, to airplanes and motorcycles, to trains, bikes, buses, and even pedestrians.
“One accident we reconstructed involved a drunk guy on a lawn mower who was using a flashlight as a headlight to drive home from a local bar,” recalled Cheek, whose firm uses its expertise for heavy trucks, buses, and commercial motor vehicles. And it’s not just vehicles that use accident reconstruction. The construction industry also has injury-causing accidents that require investigation, as do work zones and roadway maintenance.
Vickie Norton is both a project engineer with MEA Forensic Engineers and Scientists and a full-time airline transport pilot. “I’m first and foremost a mechanical engineer,” she noted, “and after becoming a private pilot, I worked my way up through the pilot ratings to instructing and commercial flying.”
Initially Norton was hired by Douglas Aircraft as an engineer and became interested in aviation accident and incident investigation. “Accidents involve not only small, general aviation aircraft with less-experienced pilots, but also very sophisticated aircraft piloted by professional flight crews with thousands of hours. To ultimately uncover the contributing and causal factors of the accident is vital from a safety perspective,” she said.
It’s also a field that is open to engineers at the beginning of their careers. Renee Brumbaugh recently graduated from the Colorado School of Mines with a degree in mechanical engineering. She began her career as an accident reconstructionist at Kineticorp™. “For the most part, I’ve been working on car crashes, which has a lot of physics such as conservation of momentum and conservation of energy,” she said. She didn’t know about accident reconstruction as a career until her senior year when a job description by Kineticorp caught her interest.
Typical undergraduate engineering degree programs do not offer courses in accident reconstruction. Most engineers learn about it on the job and through continuing education programs offered by organizations such as SAE International. Beverly Longdon has worked with SAE for more than 20 years identifying education courses that are needed to assist engineers in this field of study, recruiting experts to teach courses, and assisting them in creating sound educational programs. The program has grown and is now one of SAE’s most popular certificate programs, offering more than 20 different courses designed to help engineers gain experience in many aspects of accident reconstruction for both individuals new to the field and those who need to obtain continuing education credits for their professional engineering licenses. Participants learn the technical knowledge and skills to understand the fundamentals of crash and vehicle dynamics and how vehicle systems, subsystems, and onboard technology influence that process.
“Accident reconstruction is an exciting field and most don’t know about it when beginning their engineering education,” Longdon noted. “The person who does accident reconstruction has to know so much about the vehicle, not just analyzing the scene.”
When an accident occurs, the facts relating to vehicle speed, avoidance, sight distance, collision severity, and code violations are critical to the legal process. “Even minor impacts and collision events may require the expertise that would otherwise be left up to general nonscientific interpretation,” said Cheek. “We are usually retained by attorneys, insurance companies, fleet/safety managers, and local state and law enforcement departments.”
Human, machine, and environment
To gain needed facts, fundamental science is combined with the newest technologies to reconstruct accidents and arrive at conclusions about circumstances, causes, and preventive measures. According to the SAE Accident Reconstruction Certificate Program, “Crash reconstruction utilizes principles of physics and empirical data to analyze the physical, electronic, video, audio, and testimonial evidence from a crash to determine how and why the crash occurred.” To Norton, the initial investigative approach can be summed up into three realms: human, machine, and environment.
In Norton’s field of aviation accidents and incidents, human issues include: pilot training, qualifications, preflight preparation, recency-of-experience, decision-making, and fatigue/health issues, to name a few. However, pilots aren’t the only humans involved. Often the actions and influences of mechanics, air traffic controllers, dispatchers, passengers, and owner/operators must also be considered. As for the machine: Was it mechanically sound and properly maintained? Was it properly equipped and fueled to fly that particular mission? Was a proper weight-and-balance/loading check performed? Regarding the environment, weather conditions typically get the brunt of the scrutiny; other considerations, however, include mountainous terrain, operations in congested airspace, night flying, visual illusions, communication issues, etc.
“When ultimately narrowed down to the machine,” Norton commented, “isolating a system, or even a single component, that might be responsible can require the skills of a number of engineering disciplines.” These can include mechanical, metallurgical, material, chemical, and occasionally even environmental experts. In addition Norton noted, “Actual technologies include microscopy, metallography, fractography, and stress analysis. We employ any and all relevant expertise to help discern whether a component failure was related to deficiencies in design, manufacturing, maintenance, or use.”
Engineers at MEA Forensic consider all possible contributing and causal factors from the actions of the flight crew to microscopic defects inside a failed component. When tangible data for the aircraft and its flight path are available, experts can animate the event to render a real-time representation of the flight and accident sequence, including pilot inputs, altitude changes, airspeed fluctuations, engine power production, flight control surface movements, and pilot/air traffic control communications.
According to Kineticorp, investigating an accident is multidisciplinary as it requires expertise in areas such as mapping techniques, photography, vehicle data forensics, human factors, and mechanical and component failures. Using cutting-edge analytical techniques, the company’s team of experts gathers, analyzes, and interprets physical and digital evidence to deliver an accurate picture of how an accident happened. Engineers and visualization staff together create trial exhibits that represent and communicate their findings in a clear, concise, and compelling manner.
A thorough investigation requires steps. The first is gathering evidence. For example, SAE’s Accident Reconstruction Certificate Program participants learn to: describe the basic evidence documentation techniques; recognize different types of evidence produced by various collision types; describe the basic mechanics of collision; summarize the principles of planar impact mechanics and crush analysis; describe the forms of analysis applicable to each collision type; and summarize the empirical data available in the literature for each collision type. The end result is a combination of physical evidence and interpretations of what occurred.
Collecting the numerous amounts of evidence can include such factors as the roadway, the vehicle, medical records, and investigating seat belts. “Once we collect evidence, we analyze that evidence through creating a diagram of the vehicles to understand how they came together, how they moved toward the impact, within the impact, and away from the impact,” said Cheek. “Once you understand that, then you can focus on the occupants of the vehicle and how they moved and how the injuries occurred. We collect evidence, study, and analyze this evidence and present our findings.” In addition, Brumbaugh pointed out that the attorneys handling the case provide police reports, photos taken at the scene, legal claims, and documentation.
New technologies aid precision
New technologies are an integral part of accident reconstruction. “Advancements in technology have changed how we work and have given us tools that help us do our jobs better,” said Cheek. “When I started in this field 25 years ago, tape measures and rolling measuring wheels were the tools of the trade. Now we use 3D laser scanners and drones that allow us to work faster and capture more information while doing so in a safer manner.”
Computer simulation is another technology that allows accident reconstructionists to simulate crashes and refine their analyses, as do computer animations that effectively reveal how a crash occurred. “Through an animation, we can put people in the driver’s seat to show what the view was like leading up to a crash,” added Cheek, who also noted that black boxes are another component adding to the growth of accident reconstruction. “When black box technology was introduced into cars, people thought we would no longer need to reconstruct accidents. If anything, they caused a greater need for people trained in the field of accident reconstruction to properly understand and interpret its information in context of the crash,” observed Cheek.
Drones and unmanned aircraft systems (UAS) have become a major game changer for those investigating collisions. Not only do they reduce accidents and injuries that can occur while collecting evidence along a busy highway, but they also can obtain enough information to construct a mock accident scene from various drones, flight levels, and angles. In addition, aerial photogrammetry by UAS and photogrammetry software such as Pix4D® have produced even greater accuracy, which in the form of maps and diagrams can be used as evidence both for the reconstruction experts and in the courtroom. Pixel tracking determines the position and speed of objects that were filmed by one camera. Video footage tracks objects based on the change in pixels that represent an object’s movement, such as the speed of a vehicle.
Photogrammetry is another new technology that extracts 3D information from photographs by overlapping photos to create a point cloud. This allows for perspectives that couldn’t be seen before. Using both a drone and scanner photogrammetry ties data sets together, which allows information on specific locations within an inch.
While acquiring and analyzing electronic information to investigate automotive accidents has grown since the late 1990s, endpoint detection and response (EDR) is an emerging technology that is rapidly becoming an effective tool for accident reconstruction. According to SAE’s Accident Reconstruction Program, EDR is a category of tools and solutions that focus on detecting and investigating. EDR records interval and duration, resolution, accuracy, and time latency. It then articulates the limitations to apply the data to crash analysis. For instance, it calculates minimum and maximum speeds prior to the loss of control or braking and at impact based on the last accurate EDR pre-crash speed data point. Crash data retrieval (CDR) is another technology comprising hardware and software that provides accident reconstructionists data from evidence stored in a vehicle such as vehicle speed, crash severity, seat-belt status, brake status, and ignition cycles.
The FARO® 3D laser scanner allows accident reconstructionists to scan an environment to create an accurate model. “It’s a big part of our job,” stated Brumbaugh. “Without it, we wouldn’t be able to make such a high-resolution model. We can get millions of data points to make 3D models. Our visualization team takes the data and can create a computer diagram of the scene and vehicles.”
Another major improvement in accident reconstruction is interactive animations that provide an in-depth investigation of a crash by using the freedom of motion, timing, and perspective. All these graphical and visual trial exhibits give a jury more understanding about complex information.
“Ultimately, we have to present these findings,” noted Cheek. “In the work that I do, the findings are often presented in the legal environment. It can be intimidating and also rewarding to help a jury understand some of these complex issues so that they can come to a reasonable decision when there’s a dispute between two parties. Every situation is unique, and they all have their own complex issues.” He pointed out that very often the findings are presented to people on a jury with no scientific or engineering background, thus the terminology must be made understandable.
With more vehicles on roadways, there are more possible collisions, thus a tremendous growth in the field of accident investigation and reconstruction over the past decades. “Some people believe that autonomous vehicles will eventually eliminate crashes on our roadways. While we can hope for that, it will take many years before the technology has proliferated into our society to reach that goal,” said Cheek. “In the meantime, there is a great need for engineers in this field to study why crashes happen and how to reduce or eliminate them altogether.”
With her many years in the field, Norton continues to find the work fascinating. Addressing the dual importance of personal satisfaction and making a contribution, she observed that “the ultimate goal is to utilize some type of engineering degree to further your industry, while at the same time affording you an extremely rewarding career.”
Brumbaugh agrees that not many people are familiar with accident reconstruction and there are not many females involved in it. However, she noted the advantages she’s seen. “You are constantly doing something new depending on where you are in the case. It could be reading depositions, traveling to survey a scene, or doing analysis to writing a report. There are lots of different aspects.”