Working Knowledge: Data Driven; February 2004; Scientific American Magazine; by Mark Fischetti; 2 Page(s)

Cars and trucks have a small, rugged box of electronics that can reveal how the vehicle was operating before a crash. Few drivers were aware that they were sitting on such hardware until last August, when police sought the box from U.S. Representative Bill Janklow's Cadillac after he hit and killed a motorcyclist in South Dakota.

Event data recorders began to be installed in U.S. passenger vehicles in the mid-1970s to deploy air bags when they detect extreme changes in velocity. Automakers gather data from boxes in random accidents to analyze which velocity deltas, stored by the boxes, caused deployment - useful for improving designs. But since 1999 the units, typically installed under the front seat carpet, now record vehicle speed, engine rpm, degree of throttle (accelerator) and brake deployment, and seat-belt engagement. Coupled with crash injury reports, the data are used to enhance performance or to help in recalls of faulty systems.