Injury Assessment Using the NASS Data Files
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The National Automotive Sampling System (NASS), a division of
the U.S. National Highway Traffic Safety Administration (NHTSA),
is an invaluable database to those in the insurance and legal
industries.
The Crashworthiness Data System (CDS) of NASS keeps data on
thousands of crashes. Research teams at Primary Sampling Units
across the country study 5,000 crashes annually. Skid marks,
fluid spills, broken glass, and bent guardrails are studied
at crash sites. Vehicles are then located to be photographed,
measured, and to identify the interior locations struck by occupants.
Researchers then interview crash victims and review medical
records to determine the nature and severity of injuries.
There are more than 140,000 crash files in the NASS CDS. Although they are designed for analysis with a specialized statistical analysis package, analysis can also be conducted simply by going to the Web site and selecting a list of cases meeting specified criteria. (Click here to view site.)
Similar statistic-based crash data has been gathered by Transport Canada but in a more focused form, however, it is not available for public analysis.
How data affects civil litigation…
NASS data can be used to examine the effect that seat belt use might have on a plaintiff’s injuries. For example, an unrestrained driver of a Chevrolet Cavalier sustains bi-lateral rib fractures and internal injuries in a frontal impact with another car. The NASS data can be used to select all the frontal impacts involving Cavaliers and compare the injuries of those drivers to that of the plaintiff. The NASS data not only indicates whether a driver was wearing a seat belt but also provides detailed information on the size (height, weight) of the occupant, the severity of the crash in terms of change-in-velocity, the existence of structural intrusion into the occupant’s space, and the source of each injury.
Other uses might be to compare the physical evidence from the subject collision to those in the NASS files to support the reconstruction of a collision. The NASS data contains:
- Information about the point of impact and final rest positions of the vehicles
- The extent of crush and location of the direct contact damage
- Actual crush measurements
- Photographs of damaged vehicles and collision sites
Litigation concern…
Determining the severity of an accident victim is a concern.
Medical practitioners usually make this judgment; however, the
NASS data provides independent evidence about similar injuries
sustained in similar collisions. The NASS data links the injury
data familiar to the medical practitioner to the unfamiliar
accident data. Although medical practitioners may have their
own sources of data to draw conclusions, they do not have sufficient
familiarity with the NASS data to conduct an inquiry and report
on its meaning.
Engineers frequently provide their background in calculation of speed or impact force to justify their injury assessment opinions. Given the small sample of collisions that most engineering experts examine, they do not have access to the larger view of where a specific accident falls in comparison to many other similar events. Only a review of a large body of detailed information, as contained in NASS, can provide such a comparison.
Specialized knowledge required when using NASS…
Efficient assessment of the NASS files requires specialized knowledge of their research methods and coding schemes. For example, NASS uses an injury scaling scheme called the Abbreviated Injury Scale (AIS). The AIS is assigned based on the probability that the injury will cause death and separates injuries from their outcomes.
The Occupant Injury Classification (OIC) is a series of codes
meant to describe the location, body system, severity, and source
of an injury. And unless an expert has had specific training
in this coding scheme it cannot be used efficiently to select
the specific injuries needed to be reviewed.
Another specific coding scheme is the Collision Deformation Classification (CDC), designed to describe vehicle damage according to its location, magnitude, and general collision type. A code example is “12FDEW3.” This defines an impact from a predominantly rearward force to the front surface of a vehicle, distributed broadly across the surface, including the bumper level, with an extent of crush penetrating into the middle of the vehicle’s hood. If the expert is not familiar with this coding scheme, any NASS analysis based on it will most likely be flawed.
At Gorski Consulting we are familiar with these coding schemes as we have used them extensively.