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Event Data Recorders

Basic Description

Car bus accidentEvent data recorders (EDRs), sometimes referred to as automotive "black boxes", are systems that constantly record information related to the vehicle operation. In the event of an accident, the recorder saves the information that was recorded several seconds just before and/or just after the collision. EDRs may be independent electronic control units or they may reside within other control modules such as the engine control (ECM) or airbag control module.

Unlike Accident Recorders, which are after-market systems that usually record video and GPS location data, EDRs are installed by the vehicle manufacturer and integrated with existing systems and sensors. Although automotive EDRs have existed in one form or another since the mid-1970s, they have only recently become standard equipment in most vehicles. The National Highway Traffic Safety Administration (NHTSA) estimates that about 96% of model year 2013 cars and light trucks are equipped with EDRs. Modern EDRs record various vehicle operation parameters such as vehicle speed, pedal positions, steering wheel position and other information that may be relevant to a crash investigation. There is some consumer resistance to vehicle black boxes due to privacy concerns, and the fear that information recorded by a black box could be used against the vehicle owner in a lawsuit resulting from an accident.

In 2006, the National Highway Traffic Safety Administration (NHTSA) published standards for EDR practices, but did not require EDRs as standard equipment [6]. It only specified which data EDRs should collect and how it should be stored. The NHTSA standard would require all cars with EDRs to record the following information:

  • Change in forward crash speed
  • Maximum change in forward crash speed
  • Time from beginning of crash at which the maximum change in forward crash speed occurs
  • Speed vehicle was traveling
  • Percentage of engine throttle, percentage full (how far the accelerator pedal was pressed)
  • Whether or not brake was applied and the anti-lock brakes were activated
  • Ignition cycle (number of power cycles applied to the EDR) at the time of the crash
  • Ignition cycle (number of power cycles applied to the EDR) when the EDR data is downloaded
  • Whether or not driver was using a safety belt
  • Whether or not frontal airbag warning lamp was on
  • Driver frontal airbag deployment: time to deploy for a single stage airbag, or time to first stage deployment for a multistage airbag
  • Right front passenger frontal airbag deployment: time to deploy for a single stage airbag, or time to first stage deployment for a multistage airbag
  • Number of crash events
  • Steering wheel angle
  • Vehicle roll angle, in case of a rollover
  • Front seat positions
  • Time between first two crash events, if applicable
  • Whether or not stability control was engaged
  • Whether or not EDR completed recording

The NHTSA standard would also specify parameters for recording such things as sideways acceleration, forward or backward acceleration, engine speed, driver steering input, right front passenger safety belt status, engagement of electronic stability control system, anti-lock brake activity, side airbag deployment time for driver and right front passenger, seat track positions for both the driver and right front passenger, and occupant size and position for drivers and right front passengers. The NHTSA proposal also requires that automakers provide a commercially available tool for downloading the EDR data.

In December of 2012, NHTSA proposed that EDRs complying with the 2006 standard be required in all light passenger vehicles beginning September 1, 2014 [9]. The EDR data would be treated by NHTSA as the property of the vehicle owner and would not be used or accessed by the agency without owner consent.

vehicle speed, engine rpm, steering wheel angle, angular rate sensor, accelerator pedal position, throttle position, brake pedal switch, seat position, occupant weight and position
Data stored in electronic memory card
Data Communications
Bosch, Continental, Delphi
For More Information
[1] Event Data Recorder, Wikipedia.
[2] Harris Technical Services: Event Data Recorders, Jim Harris.
[3] NHTSA Event Data Recorder Research Website, NHTSA website.
[4] USA: GM Supports Event Data Recorder Mandate,Telematics News, Feb. 27, 2010.
[5] Q&A: Event Data Recorders, Insurance Institute for Highway Safety website, Nov. 2010.
[6] Black Box 101: The Basics of Event Data Recorders, Consumer Reports, Mar. 18, 2010.
[7] Event Data Recorder (EDR) Links, Ruth Consulting website.
[8] Automotive Black Boxes, Minus the Gray Area,, May 23, 2011.
[9] U.S. DOT Proposes Broader Use of Event Data Recorders ..., NHTSA press release, Dec. 7, 2012.
[10] Yes, Your New Car Has A 'Black Box.' Where's The Off Switch?, NPR All Things Considered, Mar. 20, 2013.