Event data recorder

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An event data recorder or EDR is a device installed in some automobiles to record information related to vehicle crashes or accidents. In modern diesel trucks, EDRs are triggered by electronically sensed problems in the engine (often called faults), or a sudden change in wheel speed. One or more of these conditions may occur because of an accident. 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.


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 the brakes were applied, 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) that may transmit some data, such as an alert that the airbags have been deployed, to a remote location.

Most EDRs in automobiles and light trucks are part of the restraint system control module, which senses impact accelerations and determines what restraints (airbags and/or seatbelt tensioners) to deploy.[citation needed] After the deployment (or non-deployment) decisions are made, and if there is still power available, the data are written to memory. The data downloaded from older EDRs usually contain 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 on the circumstances of the collisions and the time interval between them, among other things.

It is also possible that no data can be recovered from a data recorder. One situation where this might occur is a catastrophic loss of electrical power early in a collision event. In this situation, the power reserve in the restraint system control module capacitors may be completely spent by the deployment of the air bags, leaving insufficient power to write data to the EEPROM. There are other circumstances where a module may fail to record a data file as well.

Most EDRs in heavy trucks are part of the engine electronic control module (ECM), which controls fuel injection timing and other functions in modern heavy-duty diesel engines.[citation needed] The EDR functions are different for different engine manufacturers, but most recognize engine events such as sudden stops, low oil pressure, or coolant loss.[citation needed] Detroit Diesel, Caterpillar Inc., Mercedes-Benz, Mack Trucks, and Cummins engines are among those that may contain this function. When a fault-related event occurs, the data is written to memory. When an event triggered by a reduction in wheel speed is sensed, the data that is written to memory can include almost two minutes of data about vehicle speed, brake application, clutch application, and cruise control status. The data can be downloaded later using the computer software and cables for the specific engine involved. These software tools often allow monitoring of the driver hours of service, fuel economy, idle time, average travel speeds, and other information related to the maintenance and operation of the vehicle.

Some EDRs only keep track of the car's speed along its length and not the speed going sideways.[citation needed] Analysts generally look at the momentum, energy, and crush damage, and then compare their speed estimates to the number coming out of the EDR to create a complete view of the accident.[1]

Data from the Eaton VORAD Collision Warning System[edit]

The Eaton Vehicle Onboard Radar (VORAD) Collision Warning System is used by many commercial trucking firms to aid drivers and improve safety. The system includes forward and side radar sensors to detect the presence, proximity and movements of vehicles around the truck and then alert the truck driver. When sensors determine that the truck is closing on a vehicle ahead too quickly or that a nearby vehicle is potentially hazardous, the VORAD system gives the driver both a visual and audible warning. The VORAD system also monitors various parameters of the truck including vehicle speed and turn rate plus the status of vehicle systems and controls. The monitored data is captured and recorded by the VORAD system. This monitored data can be extracted and analyzed in the event of an accident. The recorded data can be used by accident investigators and forensic engineers to show the movement and speed of the host vehicle plus the position and speeds of other vehicles prior to the incident. In accident reconstruction, the VORAD system is a step above the EDR systems in that VORAD monitors other vehicles relative to the host vehicle, while EDR’s only record data about the host vehicle.[2]


Conducting a bench download
Downloading a module via the DLC

Event data recorders were introduced to American open-wheel championship CART in the 1993 season,[3] and the Formula One World Championship in 1997.[4] This allowed to study crashes that allow to develop new car rules and track safety measures that reduce damages.

Usage of the device in road vehicles varies widely from manufacturer to manufacturer. General Motors and Ford implement the technology on most of their recent models, while Mercedes-Benz and Audi do not use EDRs at all[citation needed]. As of 2003, there were at least 40 million vehicles equipped with the devices.[5] In the UK many police and emergency service vehicles are fitted with a more accurate and detailed version that is produced by one of several independent companies. Both the Metropolitan police and the City of London police are long-term users of EDRs and have used the data recovered after an incident to convict both police officers and members of the public.

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. Alternately, some modules can be downloaded "on the bench" after removal from the vehicle, as shown to the left.

The only system capable of downloading commercially available crash data in North America is Bosch Diagnostic's Crash Data Retrieval System.

NHTSA's Event Data Recorder Ruling[edit]

From 1998 to 2001, the National Highway Traffic Safety Administration (NHTSA) sponsored a working group specifically tasked with the study of EDRs. After years of evaluation, NHTSA released a formal Notice of Proposed Rulemaking in 2004. This notice declared NHTSA’s intent to standardize EDRs. It was not until August 2006 that NHTSA released its final ruling (49 CFR Part 563). The ruling was lengthy (207 pages), consisting of not only definitions and mandatory EDR standards, but also acted as a formal reply to the dozens of petitions received by NHTSA after the 2004 notice.

Since there was already an overwhelming trend for voluntary EDR installation, the ruling did not require manufacturers to install EDRs in vehicles produced for North America. Based on its analysis, NHTSA estimated that by 2010, over 85% of vehicles would already have EDRs installed in them, but warned that if the trend did not continue, the agency would revisit their decision and possibly make installation a requirement.

The mandate did, however, provide a minimum standard for the type of data that EDRs would be required to record: at least 15 types of crash data. Some of the required crash data include pre-crash speed, engine throttle, brake use, measured changes in forward velocity (Delta-V), driver safety belt use, airbag warning lamp status and airbag deployment times.

In addition to the required data, NHTSA also set standards for 30 other types of data if EDRs were voluntarily configured to record them. For example, if a manufacturer configured an EDR to record engine RPMs or ABS activity, then the EDR would have to record 5 seconds of those pre-crash data in half-second increments.

Besides the requirement that all data be able to survive a 30 MPH barrier crash and be measured with defined precision, NHTSA also required that all manufacturers make their EDR data publicly available. As of October 2009, only General Motors, Ford and Daimler Chrysler had released their EDR data to be publicly read. In the August 2006 ruling, NHTSA set a time table for all vehicle manufacturers to be in compliance with the new EDR standards. The compliance date was originally set for all vehicles manufactured after September 1, 2010. NHTSA has since updated its ruling (49 CFR Part 563 Update) to give vehicle manufacturers until September 1, 2014 to be in compliance with the original ruling.

Privacy concerns[edit]

Despite alerts and warnings in their vehicle owner's manual, 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. But the use of EDR data in civil and criminal court cases is on the rise as they become more accepted as a source reliable empirical evidence in accident reconstruction.[6]

Fourteen states have statutes specific to EDRs. Generally, these state statutes restrict access to the EDR or limit the use of recovered EDR information.

Use as evidence in courts[edit]

There have been a number of trial cases in the US and Canada involving EDRs. Drivers have been convicted and exonerated as a result of EDR evidence.

Other examples include:

  • In New South Wales, Australia, a teen-aged female (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), who was speeding. There were no other witnesses to the crash.
  • The first such use of EDR evidence in the United Kingdom was at Birmingham Crown Court during the trial of Antonio Boparan-Singh who crashed the Range Rover Sport he was driving into a Jeep in 2006. The accident left a baby girl paralyzed and the driver, who was aged 19 at the time of the incident, was sentenced to 21 months in prison. The EDR evidence allowed investigators to determine the driver was speeding at 72 mph in a 30 mph zone.[7]


N.J. Governor Jon Corzine[edit]

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. The Governor was not the driver of the vehicle.[8]

Mass. Lt. Governor Tim Murray[edit]

On November 2, 2011, Mass. Lt. Governor Tim Murray crashed a government-owned vehicle on a stretch of Interstate 190.[9] Initially, police investigating did not issue any citations.

Murray initially claimed he simply lost control on the ice, wasn’t speeding, was wearing a seat belt and braked. But those claims were all later disproven when the Crown Victoria black box data recorder information was released.[10] The data revealed the car was traveling 108 miles per hour, accelerated, and the Lt. Governor was not wearing a seat belt at the time the vehicle collided with a rock ledge and flipped over. Murray was unhurt in the accident.[9]

Video Event Data Recorder[edit]

Main article: Dashcam

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

See also[edit]


  1. ^ "The Ferrari That Split in Half". Slate.com. 2006-04-18. Retrieved 2010-02-24. 
  2. ^ "Operation of the Eaton VORAD Collision Warning System and Analysis of the Recorded Data". David Danaher, P.E., Jeff Ball, Ph.D., P.E., Trevor Buss, P.E., and Mark Kittel, P.E. 2012-06-14. Retrieved 2012-07-05. 
  3. ^ Indy race cars are equipped with CRASH DATA RECORDERS to improve safety - Instrumented Sensor Technology
  4. ^ The Analysis of Accident Data Recorder (ADR) Data in Formula 1 - Peter G. Wright, SAE Technical Paper, 13 November 2000
  5. ^ Sharp, Deborah (2003-05-15). "Autos' black-box data turning up in courtrooms". USA Today. Retrieved 2010-02-22. 
  6. ^ "Is That a 'Black Box' in Your Car?". ABC News. 2010-02-22. Retrieved 2010-02-22. 
  7. ^ "How car's black box trapped speeding Rich List heir who left baby paralysed in Range Rover crash". London Evening Standard. 2008-04-04. Retrieved 2010-02-03. 
  8. ^ "Corzine's SUV traveling 91 mph at time of crash". MSNBC.com. 2007-04-17. Retrieved 2010-02-22. 
  9. ^ a b "Lt. Gov. Tim Murray was driving 100 mph at time of Nov. crash, may have fallen asleep at the wheel". The Boston Globe. 
  10. ^ http://news.bostonherald.com/news/regional/view/20220104data_wreckslt_govs_tale/srvc=home&position=also

External links[edit]