Black Box 101: The basics of Event Data Recorders

Most new passenger vehicles are now equipped with "black box" devices that record data immediately before, during, and after a crash. Like more well-known devices on airliners, these event data recorders, or EDRs, can help police and investigators reconstruct what happened in a crash and why. They typically record information such as vehicle speed, throttle position, air bag deployment, whether brakes were applied, and if the driver was wearing a safety belt.

First introduced by General Motors in basic form on air bag-equipped models in the mid-1970s, by the 2005 model year EDRs were being used by various manufacturers in 64 percent of all new models, according to the National Highway Traffic Safety Administration (NHTSA). The Insurance Institute for Highway Safety (IIHS) says more recent data shows all new cars have some form of EDR. But the specific information gathered varies by auto manufacturer, and some companies make it easier to retrieve data than others.

Back in 2006, NHTSA mandated that all new vehicles equipped with EDRs by the 2013 model year must make the information standardized and readily accessible by authorities.
 
The regulations will require that all EDRs record at least 15 specific data elements, while more advanced devices will be required to log as many as 30 elements. Advanced devices log more information about steering input, sideways acceleration, and whether electronic stability control and ABS systems were functioning at the time of the impact. Manufacturers will be required to make information about how to download the data more readily available, and to include a statement in the owner's manual saying the vehicle is so equipped.

While domestic carmakers and some import manufacturers already make access to data available to investigators using tools made by a third-party supplier, others make it harder to obtain. Toyota in particular has faced criticism about how difficult it is to access data from their black boxes and that the company would release crash data only under court order or at the request of NHTSA.

During congressional testimony in March 2010, Toyota  officials said the company had only one laptop in the U.S. capable of downloading data from its black boxes, but pledged to make more available to officials soon.

A Toyota spokesman told us that their devices are experimental and unreliable for reporting crash data. John Hanson, National Environmental, Safety and Quality Manager said, "Our EDRs are more to help us understand how systems like ABS and air bags work." While he did say that the carmaker's recorders monitor a wide variety of parameters, including steering angle and throttle position for up to five seconds before air bag deployment, the devices are not considered fully functional or accurate.

"All those things are in there, the question is, how accurate is that data," he said. Hanson added that Toyota has shared crash data from its EDRs with NHTSA in the past. A recent Newsweek article said Toyota has supplied data in about 200 cases, but the carmaker says EDR data only changed the outcome of a case once.

General Motors is enthusiastic in its support for EDRs. Michael J. Robinson, Vice President, Environment, Energy and Safety Policy said, "Broad EDR application and collection of data will help save lives and prevent injuries."

While the devices can undoubtedly aid with crash investigation, privacy issues have been raised about the use of EDRs. According to NHTSA, captured data is the property of the vehicle owner. But even on vehicles where it is accessible, special tools are required to get it. The IIHS says police or investigators can access the data with the owner's consent, or can obtain a court order to gain access if the owner refuses.

NHTSA says field studies have shown the devices can increase driver safety by helping modify driver behavior, and the agency cites studies showing commercial fleets have seen crash reductions of as much as 30 percent in vehicles equipped with EDRs.

A study by the agency determined, "The results of the engineering analysis show that EDR data can objectively report real-world crash data and therefore be a powerful investigative and research tool, by providing very useful information to crash reconstructionists and vehicle safety researchers. Due to significant limitations however, EDR data should always be used in conjunction with other data sources."

Consumer's Union, publisher of Consumer Reports, has called on manufacturers to make information from black box recording devices standardized and more immediately accessible to government investigators, with the appropriate privacy controls. We also encourage carmakers to apply these monitoring standards to their vehicles as soon as possible--not waiting until 2012 to do so. NHTSA estimates manufacturer cost to comply with the regulations will be about 17 cents per car. (Read: " Consumers Union calls for changes to strengthen U.S. car-safety net.")

For more on safety features and resources, see our car safety section. Also see our unintended acceleration guide.

—Jim Travers