Preserving an accident scene is the first priority following a loss. Until recently, forensic engineers had to follow painstaking procedures to perform a complete inspection. Upon arrival at the scene, the engineer had to take numerous photos and measurements—as precise as possible with rudimentary tools like a measuring tape and the naked eye—and manually sketch out the scene by hand. The process is known as preserving, or memorializing, the scene. This site documentation enables forensic engineers to thoroughly reconstruct the accident to determine causation. Based on a forensic investigation of the scene and a review of documents and testimony, causation can then be categorized into three scenarios: design limitations, human error, or environmental factors.
In the weeks and months following an accident and the period leading up to a trial, the evidence may change due to environmental or other factors, and the memory of what exactly occurred may fade. Preserving the scene can solve this problem and can prove crucial in many cases. In civil cases, an accusation against a defendant must be substantiated and proven within a reasonable degree of (engineering) certainty. Therefore, the preservation or handling of evidence can be a major factor for the trial of cases.
Enter the latest generation of high-tech tools that are now available and well accepted in legal proceedings. High-resolution 3D laser scanners, rapid light detection and ranging (lidar) scanning, advanced photogrammetry, and GPS-enabled photogrammetry using drones and phones are completely changing the landscape, providing near fool-proof data that serves as indisputable evidence. These technologies help experts build accurate demonstrative evidence without the need to have a graphic artist paint a picture. The usefulness of these tools is measured by how efficiently and accurately they can capture an accident scene or evidence.
3D Laser Scanners
Stationary 3D laser scanners, such as those made by FARO or Leica, can map out everything in an entire area with millimeter accuracy. From its perch on a tripod, a 3D laser can scan millions of individual data points, capturing everything in a 360-degree line of sight scan at a resolution of one-to-two millimeters. Using proprietary software, each scan is set up and processed to create a demonstrative 3D model. Multiple scans can be stitched together to create a final rendering of a complete scene or building. The scanner can be utilized in many accident scenes, including roadway collisions, construction mishaps, building fires, and industrial equipment accidents.
The panoramic photographs and precisely measured models produced by stationary 3D laser scanners enable engineers to create incredibly accurate visuals, simulations, and animations that can be tailored to any type of investigation. For this reason, this laser scanner has been dubbed the “ultimate documenting tool” for court proceedings so that juries can easily visualize an accident. They also enable engineers to create 3D physics-based models to demonstrate how an accident could have, or could not have, occurred.
In cases where larger scenes need to be captured, flying drones, or UAVs, that are outfitted with high-resolution cameras are likely to be the ideal technique instead of stationary 3D laser scanners. Drones employ photogrammetry, which is the use of photography in surveying and mapping to measure distances between objects. When a drone flies over a scene, hundreds of photographs are captured with high-quality cameras in a matter of minutes. Each photograph is tagged with GPS coordinates and altitude to orient the photograph in 3D space. These photos are then combined to create an accurate geometrical layout of an area with elevation and 3D object profiles. In comparison, 3D laser scanners are stationary and take time to collect all data within one area, while drones collect data over a much larger area quickly and efficiently.
Drones are commonly used for roof repair estimates and inspections, particularly by civil engineers in Florida and other southeastern states where hurricanes and tropical storms wreak frequent havoc. Property insurance rates have skyrocketed in those regions in recent years due to the massive number of storm damage claims. Inspections via drone are quick, efficient, and provide accurate measurements for large areas.
Another helpful tool for capturing scenes is lidar technology, especially for situations in which drones cannot be flown but rapid measurement is desired. Lidar technology also employs the use of lasers to measure objects, but it can be deployed on a movable device, such as a phone or tablet. These devices also utilize GPS-tagged photographs to accurately determine where the device is in 3D space. The photographs and lidar measurements are combined using photogrammetry to create 3D models of scenes or evidence. The fidelity of recreated views using lidar is less than those taken by the stationary 3D laser scanners, but lidar-enabled devices allow investigators to quickly walk around a scene or a piece of evidence to capture overall dimensions. For accident reconstruction purposes, it is commonly used to make 3D models of vehicles and layouts of buildings that can be easily shared and used later for demonstrative evidence. A camera has the advantage of being handheld and can, therefore, be used in tight spots where the stationary 3D laser scanner, which must be mounted on a tripod, cannot. Thus, a GPS-tagged camera with lidar is arguably the most “user friendly” tool to have on hand.
The usefulness and acceptance of these scene-preservation tools have been well documented. In addition to the 3D scanning tools, scene documentation and accident reconstruction can be performed using other modern technologies such as body-worn cameras used by law enforcement, black-box data recorders on standard and large commercial vehicles, video captured by advanced AI-assisted driving technologies, dash-mounted cameras, and various data sources such GPS trackers, infotainment systems, traffic signal timings, and phone data. In combination, these technologies provide many tools to reconstruct an accident scene and assist with claims analyses more effectively than ever before.