Distraction, impairment, behavior among top accident risk factors

​Thanks to improvements in vehicle and road design, crash rates have been declining in the United States for several decades. Unfortunately, though, they're not dropping as fast as in other developed countries. In the 1990s, our fatality rates per mile driven were nearly the lowest among 29 countries ranked. But a Virginia Tech Transportation Institute study, published by the National Academy of Sciences, says the United States now pegs closer to the middle of the pack (17^th). 

What may have changed? The study suggests "driver behavior and performance." 

Researchers used a technique called "naturalistic observation" through onboard video and sensors to track 3,500 drivers for three years. During that time, they were able to observe what was happening in the critical seconds leading up to everything from fender-benders to serious crashes.

In 68% of the more severe crashes, researchers captured some sort of observable distraction. They compared those incidences to "model drivers" (attentive, alert and sober) and calculated the increased risk of crashing when different distractors were present. Some examples:

Distractors                                              Increase in crash risk (rounded)

Handheld phone dialing                            12 times

Reading or writing                                     10 times

Reaching for an object                               9 times

Extended glance at external object            7 times

Other distractors such as chatting with a passenger or applying makeup weren't as potent. And one presumed distractor – the presence of a child in the backseat – actually improved driver attentiveness.

Impairment was measured, too, but incidences were much less frequent. Researchers noted that because it was observable, the impairment captured probably represented more severe cases:

Impairment                                               Increase in crash risk (rounded)

Drugs/Alcohol                                           36 times

Emotional agitation
  (crying, anger)                                         10 times

Drowsiness                                                 3 times

Certain observable behaviors dramatically increased crash risk, too, although the study didn't note whether distraction or impairment also contributed:

Behaviors                                                Increase in crash risk (rounded)

Extreme driving errors

  (right-of-way)                                          936 times

  (improper/sudden stopping)                  248 times

Aggressive driving                                    35 times

Overall driving errors                                18 times

Speeding, work zone                                14 times

Speeding, well above limit/conditions     13 times

While the crash-study data is national, PEMCO analysts who reviewed it note that its takeaways probably are accurate for Northwest drivers, too. "The data collection methods help ensure its relative objectivity," said Wayne McAmis, PEMCO Claims Senior Quality Adviser.

"It captures observable distractions well," he added. "It's telling that there are six different categories for cell-phone distraction."

The upshot of the study? Researchers estimate that simply keeping our eyes and minds on the road potentially could prevent 36% (or 4 million) of the 11 million crashes each year in the United States.