Study: Automatic Braking Could Cut Injuries 50%

Autonomous braking systems could prevent 8% of rear-end collisions and reduce injuries as much as 50% when such crashes do occur, concludes a study by Virginia Polytechnic University.

The report analyzes 1,400 rear-end crashes documented between 1993 and 2008 by the National Automotive Sampling System/Crashworthiness Data System. The study was sponsored by Toyota Motor Corp.'s Collaborative Safety Research Center.

Rear-end collisions are the most common type of crash in the U.S., accounting for 17% of all accidents. Driver distraction is to blame for half of those collisions, according to the National Motor Vehicle Crash Causation Survey.

A three-phase automatic braking process would be the most effective in reducing rear-end crashes, according to the Virginia Tech researchers. They say such a system would sound a warning for the driver 1.7 seconds before an imminent collision. It would then double the driver's applied braking force at 0.8 seconds before impact or implement autonomous braking at 0.45 seconds if the driver does not respond to the original alert.

In the crashes analyzed, 71% of drivers applied the brakes before impact, and 29% did not. Sounding a warning sooner than 1.7 seconds before impact would prevent more crashes. But the Virginia Tech researchers say earlier warnings also would produce more false alarms that could prompt the driver to ignore or turn off the system.