Q&A: Event data recorders

February 2013

1 What is an event data recorder (EDR)?

Popularly called a "black box," an event data recorder is a device that records certain information from a vehicle immediately before and/or during most serious crashes. Police, crash investigators and others can download the data from the EDR's memory to help them better understand what happened to the vehicle and how the safety systems performed, and in some cases, help establish culpability. Most EDRs are built into a vehicle's airbag control module and record information about airbag deployment. However, some vehicles also record precrash data, like engine throttle and vehicle speed from the engine control module.

Some airbag and engine control modules store only diagnostic trouble codes and whether there was a signal to deploy airbags and belt tensioners. These modules aren't considered to have EDRs, so they aren't covered under federal rules. Devices that record vehicle speed before a crash or speed change during impact are defined under federal rules as EDRs.

2 Are passenger vehicles required to have EDRs?

Currently, EDRs aren't mandatory, but many automakers choose to include them in their cars. In December of 2012, the National Highway Traffic Safety Administration (NHTSA) proposed a rule requiring the devices in all 2015 and later model vehicles. Office of the Federal Register. 2012. National Highway Traffic Safety Administration – Notice of Proposed Rulemaking. Docket no. NHTSA-2012-0177; 49 CFR Part 571 Federal Motor Vehicle Safety Standard; Event data recorders. Federal Register, vol. 77, no. 240, pp. 74144-74159. Washington, DC: National Archives and Records Administration.

In August 2006, NHTSA issued an EDR rule that standardizes the information EDRs collect and makes retrieving the data easier. This rule, which applies to 2013 and later models, requires devices defined as EDRs to record 15 data elements, including vehicle deceleration, in specific formats. More advanced EDRs may record additional information from the engine control module, antilock brakes and other vehicle systems. Federal rules outline as many as 30 extra data elements that advanced EDRs must log. Vehicle manufacturers must publicly share information about how to download EDR data, and they have to include a statement in the owner's manual telling consumers that their vehicle has an EDR. Office of the Federal Register. 2006. National Highway Traffic Safety Administration – Final rule. Docket no. NHTSA-2006-25666; 49 CFR Part 563 Event data recorders. Federal Register, vol. 71, no. 166, pp. 50998-51048. Washington, DC: National Archives and Records Administration.

3 What data do EDRs record?

As of model year 2013, all EDRs must record: Office of the Federal Register. 2006. National Highway Traffic Safety Administration – Final rule. Docket no. NHTSA-2006-25666; 49 CFR Part 563 Event data recorders. Federal Register, vol. 71, no. 166, pp. 50998-51048. Washington, DC: National Archives and Records Administration.

• 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
• 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 were downloaded
• Whether or not driver was using 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
• Time between first two crash events, if applicable
• Whether or not EDR completed recording

4 What do advanced EDRs record?

For EDRs capable of logging more detailed vehicle information, NHTSA requires the devices to record such things as sideways acceleration, forward or rearward acceleration, engine speed, driver steering input, right front passenger safety belt status, engagement of electronic stability control system, antilock brake activity, side airbag deployment time for driver and right front passenger and seat track positions for both the driver and right front passenger. Occupant size and position for drivers and right front passengers may also be recorded.

5 What vehicles have EDRs?

NHTSA estimated that about 64 percent of 2005 model passenger vehicles had the devices. By 2005, General Motors, Ford, Isuzu, Mazda, Mitsubishi, Subaru and Suzuki were all voluntarily equipping all of their vehicles with EDRs, according to NHTSA. National Highway Traffic Safety Administration. 2006. Final regulatory evaluation – event data recorders. Table III-1: Estimate of the number of EDRs in light vehicles with a GVWR of 3,855 kilograms (8,500 pounds) or less. July 2006. p. 111-12. Washington, DC: U.S. Department of Transportation. Recent information from NHTSA indicates that 91.6 percent of new passenger vehicles have EDRs, although those EDRs may not include all of the data elements specified in the NHTSA rule.

6 What kinds of crashes are recorded?

Some EDRs in recent model vehicles can gather information from frontal, side, rear and rollover impacts. The original EDRs in GM and Ford vehicles, for example, collected information only from frontal and rear impacts. 

7 What are the potential uses of the data?

EDRs can provide information about a crash that can't be obtained through more traditional investigation techniques. Police, crash investigators, automakers, insurance adjusters and highway safety researchers can use this information to analyze what occurred during a crash. The data may help automakers improve occupant restraint systems and vehicle structures. National Highway Traffic Safety Administration Event Data Recorder Working Group. 2001. Event data recorders: summary of findings. Final report. Washington, DC: U.S. Department of Transportation. Gabler, H.C.; Gabauer, D.J.; Newell, H.L; and O'Neill, M.E. 2004. Use of event data recorder (EDR) technology for highway crash data analysis. NCHRP Project no. 17-24; Contractor's final report. Washington, DC: Transportation Research Board.

EDRs may be useful in determining culpability. For example, EDR data from a car involved in an August 2002 crash in Florida showed the vehicle was traveling at 114 mph seconds before it struck another vehicle, killing two passengers. The EDR data were used to convict the driver of manslaughter. Matos v. Florida, 899 So. 2d 403 (2005).

8 Do the data have limitations?

Yes, useful as EDR data may be to researchers and others, there are limitations. Some EDRs restrict data retrieval to the maker of the vehicle.

EDR data may not always survive a crash. The Institute downloaded data from 15 2001-08 GM models and two 2003-05 Ford models after 40 mph frontal offset crash tests. The EDRs in the GM vehicles accurately recorded precrash speeds, airbag deployment times and belt use. They also recorded vehicle decelerations during the crashes, but the EDRs in 7 of the 15 cars stopped recording before the crashes ended. The EDRs in the two Ford models recorded airbag deployment times and belt use, but both stopped recording vehicle deceleration data before the crash was over. Likewise, NHTSA reviewed the results of 37 crash tests in vehicles equipped with EDRs and found that the majority of EDRs didn't record the entire crash event. Niehoff, P.; Gabler, H.C.; Brophy, J.; Chidester, C.; Hinch, J.; and Ragland, C. 2005. Evaluation of event data recorders in full systems crash tests. Paper no. 05-0271. Proceedings of the 19th International Technical Conference on the Enhanced Safety of Vehicles (CD-ROM). Washington, DC: National Highway Traffic Safety Administration. Data retrieved from newer vehicles subjected to IIHS crash tests, including GM and Ford models, indicate the EDRs are now capable of recording the entire crash event.

Retrieving data from EDRs after a crash can be difficult. During 2002 and 2003, NHTSA investigators couldn't retrieve data in about one-third of their attempts. In some cases, the EDR didn't have any data. In other cases, vehicle damage prevented downloading the data, the owner wouldn't provide access to the EDR or technical or training issues got in the way. Hinch, J.; Chidester, A.; Brophy, J.; and Roston, T. 2004. The use of EDR technology to support NHTSA's crash investigation programs. PowerPoint presentation at the SAE Highway Vehicle Event Data Recorder Symposium, June 2004.

9 Who owns the data and who has access?

EDRs and the data they store belong to vehicle owners. Police, insurers, researchers, automakers and others may gain access to the data with owner consent. Without consent, access may be obtained through a court order. For example, in a Florida criminal case involving a vehicular manslaughter charge, the police obtained a warrant to access the EDR data. Matos v. Florida, 899 So. 2d 403 (2005).

For crashes that don't involve litigation, especially when police or insurers are interested in assessing fault, insurers may be able to access the EDRs in their policyholders' vehicles based on provisions in the insurance contract requiring policyholders to cooperate with the insurer. However, some states prohibit insurance contracts from requiring policyholders to consent to access. Ark. Code Ann. § 23-112-107 (e)(4) (2012) N.D. Cent. Code § 51-07-28(6) (2011).

10 Are ships, planes and trains required to have EDRs?

Yes, some planes, ships, and locomotives are required by federal or international regulations to have EDRs. Beginning in 1958, some commercial planes had to have flight data recorders that recorded five parameters including speed and altitude. The number of data elements has increased since then, and flight data recorders now must track a minimum of 88 parameters. Office of the Federal Register. 2012. Federal Aviation Administration – Title 14 Aeronautics and Space, Part 121 Operating requirements: domestic, flag, and supplemental operations, Subpart 344 Digital flight data recorders for transport category airplanes (14 CFR 121.344). Code of Federal Regulations (January 1, 2012 edition), pp.120-24. Washington, DC: National Archives and Records Administration. Since 1967, planes also have been required to have cockpit voice recorders that maintain the last 30 minutes of pilots' conversations prior to a crash. Office of the Federal Register. 2012. Federal Aviation Administration – Title 14 Aeronautics and Space, Part 121 Operating requirements: domestic, flag, and supplemental operations, Subpart 359 Cockpit voice recorders (14 CFR 121.359). Code of Federal Regulations (January 1, 2012 edition), pp.131-33. Washington, DC: National Archives and Records Administration.

Passenger ships and ships with 3,000 or more gross tonnage built after June 31, 2002, must have a voyage data recorder that records a minimum of 12 hours of data, including the ship's position, speed, and heading. International Maritime Organization. 2000. International Convention for the Safety of Life at Sea (SOLAS), 1974; December 2000 amendments. London, United Kingdom.  Available at: http://www.imo.org/blast/contents.asp?topic_id=257&doc_id=647#jun2001. Accessed: March 1, 2013.

The Federal Railroad Administration in July 1993 issued a rule requiring the lead locomotive of any train operated faster than 30 mph to have an in-service event recorder that logs, among other things, the speed, direction, throttle position, and brake application during the past 48 hours. Beginning Oct. 1, 2009, locomotives must have a crash-hardened in-service event recorder meeting crashworthiness requirements set by the agency. Office of the Federal Register. 2011. Federal Railroad Administration – Title 49 Transportation, Part 229 Railroad locomotive safety standards, Event recorders (49 CFR 229.135). Code of Federal Regulations (October 1, 2011 edition), pp. 481-84. Washington, DC: National Archives and Records Administration.

11 Are EDRs used for crash notification?

Automatic crash notification systems are designed to alert emergency responders, including police and medical personnel, when crashes occur. These systems use data from EDRs, airbag sensors and global positioning systems to identify the occurrence of crashes, their severity and the location of involved vehicles. This information is sent automatically by cellphone to emergency dispatchers or to staff at a private call center, who forward it to local 911 operators. Bachman, L.; Preziotti, G.; and Carter, A. 2001. Automotive collision notification field operational test/evaluation report. Contract no. DTFH61-95-C-00098. Washington, DC: National Highway Traffic Safety Administration.