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Digital recreation from the scene of the accident
GKS Global Services Published: 02/04/2010
To accurately record and investigate every detail of an accident scene, laser scanning may be the biggest breakthrough since digital photography. Unlike two-dimensional photographs, however, noncontact laser scanning records the scene in three dimensions, capturing every detail, measurement, and placement without disturbing any evidence. Happily, it is gaining popularity with investigators and was even used to recreate a crime scene on a popular television drama recently.
Usually, the plaintiff, the party who claims damages from a defendant, must prove the claims to be true. Therefore discovering and presenting all the pertinent evidence can be a big boon to any case. Evidence can come in many forms, including dimensional information. To capture the precise 3-D dimensions of items involved in a case, GKS Global Services, a supplier of 3-D laser scanning services for more than 25 years, has been called in many times as a neutral third party. GKS scans the accident scenes for the purposes of documenting the as-is condition, so investigators have as much information as possible to reconstruct the incident and prove which cases have merit.
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GKS was brought in to scan a bridge underpass after a tanker explosion had caused significant structural damage. The tanker truck jackknifed and fell under the bridge. The explosion and resulting fire was so hot that investigators were literally dealing with “fried concrete.” The insurance company involved needed documentation of the damage and to determine if the trucking company was liable. The Department of Transportation engineers needed to determine whether the structure was salvageable and safe or whether it needed to be completely replaced.
The long-range scan was used to check for structural damage externally and find out whether the dimensional information indicated that the internal steel reinforcement bars had melted. This type of damage would manifest in the bridge’s structure sagging.
The 3-D scan by GKS helped to determine that the bridge was indeed damaged beyond repair and would have to be demolished and rebuilt from the ground up. This kind of massive inspection project would have taken weeks or even months to complete manually. The long-range 3-D laser scanned the structure in just a few hours, and the 3-D model was available soon thereafter for the investigators to work from in determining liability.
Automakers and the National Highway Traffic Safety Administration (NHTSA) conduct crash tests on vehicle models to make sure they perform as they were designed to in a collision. GKS was hired to laser scan a vehicle before and after a crash test. The two sets of data were overlaid and compared to see if the crushed areas conformed to design expectations. Ideally, most of the crumple would occur in the engine and trunk areas, not near the passengers. This proved true in the crash test scenario. 
Unfortunately, sometimes anomalies and variations occur in vehicles as was the case in a fatal accident involving the same model. Again, GKS scanned the car in which the fatality occurred. The undamaged car provided baseline geometry, and the crash-tested car a pattern of crush in a head-on collision. These data sets were overlaid on the scan from the accident vehicle to compare the complete geometry and isolate the areas of interest.
The scan data showed that the vehicle involved in the accident displayed a crush pattern different from the expected one, allowing the body to crumple excessively in the passenger areas. This particular vehicle proved not to be crashworthy and a wrongful death suit was filed.
A large aircraft crashed while taking off. Investigators theorized that a piece of metal on the runway burst a tire, leading to a cascade of damage and a fire that eventually brought the craft down. The pieces of the plane were sequestered in a secure warehouse where GKS scanning engineers digitized the burnt and mangled debris. With the accurate 3-D data of the suspected piece of debris, experts were able to piece together the accident’s likely chain of events and determine the ultimate cause. After several years of investigation, charges were brought against several airline officials involved. The case is still pending.
Occasionally an organization from the U.S. military contacts GKS to scan an object for material analysis. In this case, the organization wanted to scan several fragments from an exploded shell casing. The shell had been exploded in a chamber and six fragments were collected for closer inspection. They were to be analyzed to see how the metal material performed against extreme forces to make them safer for troops.
A shell casing starts out as a cylinder, a very simple shape to measure and recreate by traditional measurement methods. However, when the shell explodes, the metal is distorted and deformed into irregular, twisted shards. For this type of geometry, nothing can match the capability and accuracy of non-contact 3-D laser scanning.
GKS scanned all the metal pieces in under four hours. The scan data of the jagged parts were exported into Geomagic for modeling into NURBS surfaces (3-D IGES surfaces). The models were input into an FEA (finite element analysis) computer modeling analysis package to determine material characteristics and predict behaviors.
A company involved in a wrongful death suit makes kits for building hobby aircraft. One customer built the craft, but on the first flight the engine failed. Tragically, the plane crashed and the customer died. Survivors filed a wrongful death suit against the kit-maker.
GKS scanned the airplane engine to determine its measurements and whether it met size and quality standards. The crash had distorted some of the engine parts, so the scan would also reveal those flaws when compared to the original 3-D data. Several parts were scanned and then assembled into the engine unit virtually, establishing whether the fit of the parts was correct. Some irregularities were found, supporting the plaintiff’s case.
Another wrongful death suit was filed against an automotive company because one of its car’s experienced seatbelt failure. During a crash, the seatbelt wrapped around a sharp edge in the car’s seat frame structure, which sliced through the belt. GKS scanned the sharp object’s edge, along with other objects with varying degrees of sharpness, to compare sharpness and see whether the edge that cut through the seatbelt was inappropriate for its application. The scan showed that the edge was indeed too sharp for how it was being used, and the wrongful death suit proceeded.
Laser scanning can be used successfully to settle legal disputes when physical evidence is key. The ultra-accurate data provides definitive answers about how and why an accident happened to determine root cause and which party, if any, can be held liable for part failure.
GKS Global Services is an in-house service bureau division offering complete 3-D scanning, reverse engineering, and dimensional inspection services. The company’s metrologists and engineers are experienced in the automotive, defense, electronics and many other manufacturing industries. GKS also provides terrestrial scanning services for digitizing large-scale objects, for example, bridges, buildings, power plants, mines, and ships.
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