Crash
Data Recorders
When
a traffic crash reconstructionist wanted to know the speed of a car in the
seconds before it crashed into the side of a school bus, he found that
information, and more, in the car's Event Data Recorder (EDR),
a feature quickly becoming standard on all cars. The recorder, a four-inch
square metal box, is currently installed in most recent GM vehicles and select 2000 and later Ford vehicles.
In
some ways similar to data recorders used on airplanes and trains, the car's
recorder springs into action as part of the air bag system.
Originally
designed to improve air bag performance based on the severity of the
collision, the event data recorder can tell traffic accident investigators
about the car's speed, engine RPMs, how far the accelerator pedal was pressed,
if the brakes were applied, whether the driver�s seatbelt was buckled and
what warning lights were on - all from about five seconds before impact.
When
an an air bag deployment collision accident occurs, the data is recorded onto
a computer chip. The data can be retrieved and is presented in a
report.
The
data download from the EDR will usually contain 6 to 8 pages of information. A
second impact can be recorded in the secondary, or non-deployment, file
depending upon the circumstances of the collisions and the time interval
between them.
An
air bag deployment is not required for information to be recorded. There are
circumstances where an air bag deployment command would be issued but the
algorithm used to order the deployment determines a deployment is not
warranted, such as a driver out of position before deployment is ordered. This is
a "deployment level" event. Data may be recorded for
"non-deployment" events. This can include rollover, sideswipe and
side impact accidents.
It is also possible no data can be recovered from a
data recorder. One situation where this might occur would be a catastrophic
loss of electrical power during the collision. In this situation, the entire
power reserve in the air bag control module capacitor is used to deploy the
air bags; there is none left for the recorder and no data is stored even
though the air bags deployed.
Due to the variety of circumstances in any accident, there are no guarantees
of what data may be recorded, or may be recoverable, in any specific case.
Event
Data Recorder downloads are completed by factory trained technicians at Harris
Technical Services. The technician is also a fully qualified traffic accident
reconstructionist. It is important the downloaded information and the physical
evidence be considered as a whole and the data between the recorder and the
physical evidence be compared before coming to any conclusions.
If
you would like more information, or need to arrange the recovery of data from
an event data recorder, please contact
us. The initial file review and consultation is free
and without obligation on any traffic accident case.
List of all vehicles with an EDR on
board.
Protocols
for the Recovery, Maintenance and Presentation of Motor
Vehicle Event Data Recorder Evidence (12/05).
Event Data
Recorder Case Law.
State
Statutes on Motor Vehicle Event Data Recorders.
List of EDR Data Recovery
Service Providers in North America.
Evaluation of Event Data
Recorders in Full System Crash Tests, National Highway Traffic Safety Administration, Paper
No. 05-0271.
Searching and Seizing Computers and Obtaining Electronic Evidence in Criminal
Investigations, Computer Crime and
Intellectual Property Section. U.S. Dept. of Justice, July
2002.
Use of Event Data Recorder (EDR) Technology
for Highway Crash Data Analysis, National Cooperative Highway
Research Program, Transportation Research Board of the National Academies,
Project 17-24, December 2004.
A Review of Jurisprudence
Regarding Event Data Recorders:
Implications for the Access and Use of Data for
Transport Canada Collision Investigation, Reconstruction,
Road Safety Research and Regulation.
