Collision: An Accident Reconstruction Case Study
Written by Investigator Troy Snelgrove & Bob Galvin   

A $250,000 Bentley belonging to polo magnate John Goodman slammed into a Hyundai Sonata in a Wellington, Florida intersection on February 12, 2010. The Bentley pushed the Hyundai sideways and forced it into a water-filled canal where it came to rest in an upside-down position. The trapped driver of the Hyundai, college student Scott Wilson, ultimately drowned with no other significant physical injuries.
Meanwhile, Goodman, the owner of the Bentley, was found an hour later near the collision scene. He smelled strongly of alcohol and displayed slurred speech and glassy eyes, indications that he was impaired. He complained of a head injury—a minor “bump” on his forehead—and was transported to a nearby hospital for medical care and treatment.
Two years later, a Florida judge sentenced Goodman to 16 years in prison on DUI manslaughter with failure to render aid and vehicular homicide charges, marking the end of a nationally publicized case. In spite of Goodman’s obvious impairment when he was found near the scene of the crash, there were several critical questions that needed to be answered in the course of the investigation: First, who was the driver of the Bentley at the time of the collision? Second, who—or what—caused the collision? And third, was either driver under the influence of alcohol or controlled substances?
The solid investigative work that aided in this conviction utilized multiple technologies to create an animated model of the crash scene, allowing investigators to demonstrate how the tragic crash occurred and who ultimately was at fault.
High-Profile Perpetrator
Goodman is the founder of the International Polo Club Palm Beach and well known in his community. Due to his social status and wealth, Goodman was able to obtain private counsel from a renowned south Florida law firm in his defense. Investigators with the Palm Beach County (Fla.) Sheriff’s Office knew the case would be closely scrutinized.
As with any crime scene, thoroughness was key to determining the chain of events and uncovering vital evidence. Troy Snelgrove, an investigator with the Palm Beach County Sheriff’s Office, mapped the crash scene the morning it occurred.
When he arrived at the scene, Snelgrove noted the only airbag that deployed in the Bentley was on the driver’s side. Also, boot prints could be seen in the soil leading away from the Bentley. The prints were documented.
Deputies located Goodman, who complained of the injury to his head. The deputies had Goodman taken to a nearby hospital for care and treatment. When Snelgrove visited Goodman at the hospital, he noticed that the cowboy boots Goodman wore matched the boot prints found at the crash scene; further, the boots had sand on them similar to that found near the crash site. The investigation revealed Goodman was the Bentley’s registered owner. It was also learned that Goodman had called 911 and admitted to the dispatcher that he was driving the Bentley at the time of the crash.
Dynamics of a Crash
The next step was to determine who or what caused the crash. Snelgrove noted that traffic control devices at the intersection of the crash required Goodman to stop. Wilson, the other driver, was not required to yield at the intersection and had no other traffic control devices to obey. Beyond these facts, the investigation needed to focus on determining the speed of the vehicles at points leading up to and at the site of impact.
The Hyundai’s damage was extensive and, at first glance, seemed to indicate a high-speed collision had occurred with the Bentley. After weighing the Bentley—determining a weight of 5,600 lb.—the Hyundai’s extensive damage appeared to have resulted from the weight difference between the two vehicles.
Speed calculations were performed using the linear momentum equation. This equation is based on the weights of the vehicles, the angles of approach and departure, the distance traveled after impact, and the drag factor of the roadway. The drag factor of the roadway was determined using a Vericom VC4000 electronic accelerometer computer placed in a “skid test” vehicle. The test vehicle was brought to a speed between 30-35 mph, in conditions similar to the area of the collision. The vehicle’s brakes were applied and locked, and the vehicle was brought to a stop. The VC4000 determined the initial speed, distance and time until the vehicle was stopped, and friction of the roadway in the area of the collision. These calculations allowed investigators to determine the speeds the vehicles were traveling prior to impact, throughout the collision, and how they decelerated post-collision.
Mapping, Diagramming, Animating
Next, a detailed animation of the crash was created—a step that Snelgrove knew would be essential to demonstrate the dynamics of the collision. To create a two-dimensional diagram of the scene, Snelgrove used a Sokkia 530R3 reflectorless total station with data collector running MapScenes Evidence Recorder Software to capture initial scene data points. As the points were mapped, Snelgrove could see the basic diagram forming on a display in the total station. Once the data was collected, it was downloaded into another software program, MapScenes Forensic CAD, that allowed Snelgrove to create a reconstruction diagram showing the collision dynamics determined from vehicle damage and roadway evidence. Once the diagram was completed and labeled, creation of the animation could begin.
After determining the speed calculations and dynamics of the collision, Snelgrove was able to use the module of MapScenes software to assign speeds, direction, pitch, and roll to discrete vehicle symbols. The dynamics assigned in the software were based on those determined from data and physical evidence collected at the scene, as well as speed calculations. Snelgrove then used the software to create a three-dimensional animation of how the collision occurred. The point cloud module of the software would animate the CAD diagram within the 3D point cloud, plus show dramatic fly-throughs of the point cloud scene of the Bentley and Hyundai crash.
Although the crash scene had been thoroughly mapped and diagrammed, and several months had passed since the incident occurred, an important technological twist was about to have a dramatic impact on the crash scene’s documentation and how the case would be presented in court.
A few months after the crash, the sheriff’s office received a Leica C10 scanner. Investigators opted to scan the scene in order to create a 3D animation for court presentation. The scanner consists of a laser scan head, a tripod, and targets. While the scanner shoots what it can see, it also creates shadows of what it cannot see. Numerous scans must be done to capture all of the scene details. Snelgrove and his team conducted ten scans of the area where the crash occurred.
Data recovered from the scanner was downloaded into the Leica Cyclone software, a companion program to the Leica scanner. The Cyclone software allowed the scans to be assembled using common targets. This enabled creation of a “to scale” 3D diagram of the entire collision scene. The software allows the user to get a look at the scene from any point of view.
Although this information and technology was compelling, Snelgrove still wondered how he could validate the scanner’s representation of evidence. He decided that by overlaying the 2D diagrams on top of the 3D scanned crash scene, this would provide the verification Snelgrove needed.
At this point, Snelgrove and his team agreed that the animation was ready to show to a jury. The animation showed that Goodman spent approximately six seconds in front of his vehicle, standing in the sand on the top of the canal bank, presumably watching the Hyundai sink into the water. This helped illustrate the required element of knowledge and disproved the argument that Goodman was unaware of what he struck. The application of animation technology assists everyone in the judicial system, both in criminal and civil cases, to make determinations regarding liability, guilt, and culpability.
Meanwhile, the animation module of the MapScenes software enabled Snelgrove to place a camera into the animated scene where John Goodman’s vision would be inside his Bentley. In this way, the camera could track the other vehicle as a target. Snelgrove duplicated this step for the Hyundai vehicle to show Scott Wilson’s perspective looking at the Bentley. Using this technique, Snelgrove demonstrated that there were not any visual obstructions for either driver.
Ultimately, the court sentenced Goodman to 16 years in prison. The amount of evidence in the case was substantial, but the animation played an important role by providing the jury with a clear visual representation of how the accident occurred. The saying, “A picture is worth a thousand words,” holds true—but in this case, one might say that an animation is worth a million.
About the Authors
Investigator Troy Snelgrove has been a traffic homicide investigator for the Palm Beach County (Fla.) Sheriff’s Office for ten years and a deputy sheriff for a total of 18 years. He is an instructor for the MapScenes software and is also a unit trainer.

Bob Galvin is a freelance writer who covers topics related to law enforcement and the technology of crime scene and crash scene reconstruction. His office is located in Oregon City, Ore.
< Prev


ONE OF THE CHALLENGES of writing and editing a magazine is telling a story in a relatively small amount of space. Sometimes it seems like there is never enough room to say everything that needs to be said. I find myself making tough decisions about what parts stay and what parts go.