Event data recorder

Event data recorder

An Event Data Recorder or EDR is a device installed in some automobiles and trucks to record information related to vehicle crashes or accidents. Information from these devices can be collected after a crash and analyzed to help determine what the vehicles were doing before, during and after the crash or event. The term generally refers to a simple, tamper-proof, read-write memory device, similar to the "black box" found on airplanes (as opposed to the tape recorders and video cameras common in police vehicles and many commercial trucks).


There are many different patents related to various types of EDR features. Some EDRs continuously record data, overwriting the previous few minutes until a crash stops them, and others are activated by crash-like events (such as sudden changes in velocity) and may continue to record until the accident is over, or until the recording time is expired. EDRs may record a wide range of data elements, potentially including whether or not the brakes were used, the speed at the time of impact, the steering angle, and whether seat belt circuits were shown as "Buckled" or "Unbuckled" at the time of the crash. Current EDRs store the information internally on an EEPROM until recovered from the module. Some vehicles have communications systems (such as GM's OnStar system) which may transmit some data such as an alert that the airbags have been deployed, to a remote location.

Most EDR's in automobiles and light trucks are part of the restraint system control module, which senses impact accelerations and decides what restraints (airbags and/or seatbelt tensioners) to deploy. After the deployment (or non-deployment) decisions are made, and if there is still power available, the data is written to memory. The data download from older EDRs usually contained 6 to 8 pages of information, though many newer systems include many more data elements and require more pages, depending on the make/model/year of the vehicle being evaluated. Depending on the type of EDR, it may contain either a deployment file or a non-deployment file or sometimes both, depending upon the circumstances of the collisions and the time interval between them, among other things. [ [http://www.harristechnical.com/cdr.htm Crash Data Recorders ] ]

It is also possible no data can be recovered from a data recorder. One situation where this might occur might be a catastrophic loss of electrical power early in a collision event. In this situation, the power reserve in the air bag control module capacitors may be completely spent in order to deploy the air bags, leaving insufficient power to write data to the EEPROM. [ [http://www.harristechnical.com/cdr.htm Crash Data Recorders ] ] There are other circumstances where a module may fail to record a data file as well.

Most EDR's in heavy trucks are part of the engine electronic control module, which controls fuel injection timing and other functions in modern heavy-duty diesel engines. The EDR functions are different for different engine manufacturers, but most recognize engine events such as sudden stops, oil pressure, or coolant loss. When an event occurs, data is written to memory. The data can later be downloaded using the applicable computer software and cables. Many engine manufacturers offer sophisticated software tools to allow monitoring of driver hours of service, fuel economy, idle time, average travel speeds, and other information.

This 2001 paper by W.R. "Rusty" Haight of Collision Safety Institute gives some of the history of EDRs and their use: [http://www.collisionsafety.net/documents/doc1.htm Automobile Event Data Recorder (EDR) Technology - Evolution, Data, and Reliability] .


Various groups in the United States have been engaged in lobbying the National Highway Traffic Safety Administration to develop a uniform standard for EDRs or VEDR (Video Event Data Recorder), and many support the introduction of legislation requiring installation of the devices in all new automobiles. Because EDRs are not currently required by law, usage of the device varies widely from manufacturer to manufacturer. General Motors and Ford implement the technology on most of their recent models, while Mercedes-Benz does not use EDRs at all. As of 2003, there were at least 40 million vehicles equipped with the devices. [http://www.usatoday.com/news/nation/2003-05-15-boxes-usat_x.htm USA Today article]

As of August 2006, the NHTSA published a final rule [http://www.nhtsa.dot.gov/staticfiles/DOT/NHTSA/Rulemaking/Rules/Associated%20Files/EDRFinalRule_Aug2006.pdf] standardizing requirements for EDR's voluntarily installed on all vehicles manufactured after September 1, 2010, but stopped short of requiring their installation. [http://www.nhtsa.dot.gov/staticfiles/DOT/NHTSA/Rulemaking/Rules/Associated%20Files/EDR_QAs_11Aug2006.pdf]

Downloading an airbag module in most vehicles is best accomplished by connecting the appropriate scanning tool to the Diagnostic Link Connector (DLC) usually found under the vehicle's dashboard near the driver's knees. The photo to the right shows a DLC download in progress using the Vetronix CDR Tool. Alternately, some modules can be downloaded "on the bench" after removal from the vehicle, as shown to the left.

Use as evidence in courts

Despite alerts and warnings in their vehicles' owners' manuals, many drivers are not aware of their vehicle's recording capability. Civil liberty and privacy groups have raised concerns about the implications of data recorders 'spying' on car users, particularly as the issue of 'who owns the data' has not yet been fully resolved, and there has been some controversy over the use of recorded data as evidence in court cases and for insurance claims against the driver of a crashed vehicle.

There have been a small number of cases in which a defendant was convicted as a result of data obtained from EDRs. Examples include:

*In New South Wales, Australia, a teenaged woman (a probationary driver) was convicted of dangerous driving "causing death/occasioning grievous bodily harm" in 2005. Evidence from the Peugeot's EDR showed that the car was being driven in excess of the posted speed limit. An injunction against the use of EDR evidence, obtained by the owner of the car (the parents of the defendant), was overturned in the NSW Supreme Court.
*In Quebec, Canada, the driver of a car who sped through a red light, crashing into another car at the intersection and killing the other driver, was convicted of "dangerous driving" in 2001 after EDR information revealed that it was he, not the deceased driver of the other car (as the defendant asserted), that was speeding. There were no other witnesses to the crash.

There have also been cases where data recovered from an EDR proved that the driver was obeying the speed limit.

Another discussion of EDRs and their use in court can be found here: [http://www.jlolaw.com/Articles/AutoDiagnosticModules.pdf Event Data Recorders and Their Role in Auto Accident Litigation] , by Jason Koch

Disabling an EDR

An EDR is typically mounted either under a front seat, inside the center console between the seats, or inside the dashboard. It is usually a square-ish box 4-5 inches on a side. It will have a yellow wiring harness plug, as do all airbag system components, and the plug is usually held in place by at least one "lock" to prevent it from coming dislodged inadvertently.

Disconnecting or tampering with the EDR may prevent the airbags from working. An overly simplified explanation of the way the airbags work is that an accelerometer feeds a circuit that activates the crash algorithm if the accelerometer shows a steep deceleration for several cycles in a row. The crash algorithm does various things including activating the airbags.

To disable the memory portion of an EDR there are two options: (Option 1) To disable the interface look for traces or connectors to the open plug on the box. If you cut them the data still exists, but cannot be read without someone finding and repairing the cut. (Option 2) The EEPROM is where the permanent data record is stored. If you disable it no record will be present. This does not affect the operation of the rest of the system which uses RAM as memory. The EEPROM is only used for archiving data for accident analysis--it has no operational function for the car. To disable the EEPROM cut its voltage pin. This is usually the wire on the upper right of the EEPROM. The top of the chip is marked by a half moon indentation. [http://wiki.xtronics.com/index.php/How_EPROMS_Work How EEPROMS Work] . The voltage wire is marked "Vcc" on a chip pinout.

Note that some states such as New York have laws that make it a misdemeanor to tamper with an EDR. In addition, companies modifying vehicle safety systems face steep fines from NHTSA.


On 12 April 2007, N.J. Governor Jon Corzine was seriously injured in an automobile accident. According to the superintendent of state police, an Event Data Recorder in the SUV he was traveling in recorded he was traveling at about 91 MPH five seconds before the crash. The speed limit on the road is 65 MPH. [ [http://www.msnbc.msn.com/id/18158503/ Corzine’s SUV going 91 mph when crashed - Politics - MSNBC.com ] ] The Governor was not the driver of the vehicle.

Video Event Data Recorder

A Video Event Data Recorder (VEDR) is a device which records video in a vehicle both to create a record of accidents and for evaluating driver and vehicle performance.

*An ambulance company in Ireland had installed VEDRs in their fleet and had an accident, involving a third party, successfully recover all costs from the third party insurance companies (RoadScan.co.uk).cite web|last = Lyle|first = Andrew|title=Benefits of Employing VEDR in Your Fleet|url=http://www.roadscan.co.uk/benefits/index.php|access date=22nd May 2008

See also

* Tachograph
* Black box (transportation)
* List of Vehicles with Event Data Recorders

External links

* [http://www.harristechnical.com/downloads/cdrlist.pdf List of US vehicle manufacturers with EDRs by model year]
* [http://www.harristechnical.com/cdr7.htm US State laws on accessing EDR data records]
* [http://www-nrd.nhtsa.dot.gov/edr-site/ NHTSA EDR Site] which discusses EDR technology
* [http://dms.dot.gov/search/document.cfm?documentid=283747&docketid=18029 US Department of Transportation docket 18029-1, regarding rulemaking for the EDR]
* [http://www.cnn.com/video/player/player.html?url=/video/law/2006/11/26/kaye.car.black.boxes.wsvn&checkAgain=false There's a spy in your car] , CNN, 26 Nov 2006
* [http://mfes.com/cdr.html Mechanical Forensics Eng'g Svcs] : A third party site discussing use of Vetronix/Bosch Crash Data Retrieval system to download EDRs
* [http://www.boschdiagnostics.net/products/CDR/ Bosch Diagnostics] : Sells the only tool currently available to the aftermarket (Dec 2007) for downloading airbag modules in Ford, GM, and Chrysler vehicles (formerly Vetronix Corporation).
* [http://www.cell2solutions.com/en/products.php?smenu=cameras&pid=roadcam Cell2 Solutions]


*This article contains text from [http://www.harristechnical.com/cdr.htm Harris Technical Services] and is used with .

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