Automotive black boxes or Event Data Recorders (EDRs) were originally developed to assist car manufacturers and air bag systems manufacturers to control airbag deployment. The earlier models introduced in the mid 1970s exchanged limited data with the vehicle's engine and only collected data at or about airbag deployment. Information from these devices may be collected after a crash and analyzed to help determine the status of the vehicle prior to the deployment of the airbag and for a few seconds after deployment of the airbag.
Standardization of Black Box Data
Today, the National Highway Traffic Safety Administration (NHTSA) estimates that 99.6% of motor vehicles are equipped with the EDR devices. As these devices become more sophisticated, the amount of data collected increases. Newer EDRs collect information including Longitudinal (Front to Back) and Lateral (Left to Right) Acceleration and Velocity change as well as Vertical (Up and Down) Acceleration and Roll Rates (Roll Over).
While different manufacturers of EDRs tended to record varying information in their devices, the Federal Motor Carrier Safety Administration (FMCSA) required the standardization of the type of information collected by EDRs in 2012. Black Box data must now include, brakes application, the speed at the time of impact, how far the accelerator was depressed, the engine revolutions per minute, airbag deployment, and whether seat belts were "Buckled" or "Unbuckled" at the time of the crash and more. The regulation also indicates the number of seconds of data that should be collected. This requirement was established so that valuable data could be collected for effective crash investigations and to facilitate the monitoring of safety equipment performance (like seatbelts) in the hopes of promoting safer vehicle designs.
How They Work
EDRs are made up of a tamper-proof device that writes the information it collects to electronic memory. The electronic memory usually stores only a few seconds worth of pre-crash and a few seconds of post-crash information. Some black boxes are capable of storing much more information.
Most EDR systems are constantly collecting information from the various computers in the vehicle. Black Boxes are usually part of the Supplemental Restraint System (SRS). SRSs include the sensors that can detect impact or sudden deceleration and determine what restraint systems to deploy such as Airbags or Seatbelt pre-tensioners.
The most common data elements are: whether or not the brakes were applied, the speed at the time of impact, how far the accelerator was depressed, the engine revolutions per minute, the steering angle, and whether seat belts were "Buckled" or "Unbuckled" at the time of the crash.
External transmission of some information can also occur. For example, General Motors' OnStar system currently transmits airbag deployment information along with the location of the vehicle in GPS coordinates. This transmission happens as long as the vehicle has the appropriate cell phone coverage.
The data downloaded from older EDRs usually contains several pages of information. Newer models may include many more data elements and require more pages to report. The amount of data collected is dependent upon the make/model/year of the vehicle being evaluated.
Occasionally data cannot be recovered from an Event Data Recorder. Catastrophic electrical failure or shorts, fire or destruction of the unit may prevent the data from being read.
Whether vehicles involved in accidents are passenger vehicles or commercial vehicles, the Digital Forensics experts at ESI have the knowledge, experience and technology to extract crash data from EDRs and can analyze and report the information found. Our experts are skilled in presenting this information in a manner easily digestible by both attorneys and a jury. Have a case involving a motor vehicle accident? Contact us today for your free consultation!
