Driver behavior, distraction and crash factors
April 2006 

Nearly 80 percent of crashes and 65 percent of near-crashes involved some form of driver inattention within three seconds before the event.

Primary causes of driver inattention are distracting activities, such as cell phone use, and drowsiness.

According to the National Highway Traffic Safety Administration, this important research illustrates the potentially dire consequences that can occur while driving distracted or drowsy and shows that it is crucial for drivers always to be alert when on the road.

The 100-Car Naturalistic Driving Study tracked the behavior of the drivers of 100 vehicles equipped with video and sensor devices for more than one year. During that time, the vehicles were driven nearly 2,000,000 miles, yielding 42,300 hours of data. The 241 drivers of the vehicles were involved in 82 crashes, 761 near crashes, and 8,295 critical incidents.

A huge database developed through this breakthrough study is enormously valuable in helping to understand and prevent motor vehicle crashes.

In addition, a follow-on analysis to the 100-Car Study has also been released.

Focused on the types of driver inattention and their associated risk, key findings include:

• Drowsiness is a significant problem that increases a driver's risk of a crash or near-crash by at least a factor of four. But drowsy driving may be significantly under-reported in police crash investigations
   
• The most common distraction for drivers is the use of cell phones. However, the number of crashes and near-crashes attributable to dialing is nearly identical to the number associated with talking or listening. Dialing is more dangerous but occurs less often than talking or listening
   
• Reaching for a moving object increased the risk of a crash or near-crash by 9 times; looking at an external object by 3.7 times; reading by 3 times; applying makeup by 3 times; dialing a hand-held device (typically a cell phone) by almost 3 times; and talking or listening on a hand-held device by 1.3 times
   
• Drivers who engage frequently in distracting activities are more likely to be involved in an inattention-related crash or near-crash. However, drivers are often unable to predict when it is safe to look away from the road to multi-task because the situation can change abruptly leaving the driver no time to react even when looking away from the forward roadway for only a brief time

The Database contains many extreme driving cases, including severe drowsiness, impairment, judgment error, risk taking, secondary task engagement, aggressive driving and traffic violations

Types of Driving Behavior Recorded:

1. Drowsiness
2. Driver Inattention
3. Traffic violations
4. Aggressive driving and "road rage"
5. Seat belt usage

Driver inattention was involved in nearly 80 percent of all crashes and 65 percent of all near-crashes involved driver inattention (due to distraction, fatigue, or just looking away) just prior to (i.e., within 3 seconds) the onset of the conflict.

For rear-end-striking crashes, visual inattention was a contributing factor for 93 percent of rear-end-striking crashes.
In 86 percent of rear-end-striking crashes, the headway at the onset of the event was greater than 2.0 s.
Most near crashes involving conflict with a lead vehicle occurred while the lead vehicle was moving, while 100 percent of the crashes (14 total) occurred when the lead vehicle was stopped. This indicates that drivers are sufficiently aware and able to perform evasive maneuvers when closing rates are lower and/or expectancies about traffic are not violated.

Age-related included judgment error, including secondary task performance in higher risk situations, driving while impaired, and other instances of aggressive driving, was much more prevalent in the youngest age group (i.e., 18 to 20 years) relative to the older age groups.

The rate of inattention-related crash and near-crash events decreased dramatically with age, with the rate being as much as four times higher for the 18- to 20-year-old age group relative to the older groups (i.e., 35+ years).

Hand-held wireless devices, were primarily cellular telephones, but included a small amount of PDA use, were associated with the highest frequency of distraction-related events for both incidents and near-crashes.

Driver drowsiness was a contributing factor in 20 percent of all crashes and 16 percent of all near-crashes, while most current database estimates place fatigue-related crashes at a much lower percent (i.e., under 10 percent) of total crashes.

Bibliography:

1. National Highway Traffic Safety Administration
2. Virginia Tech Transportation Institute
3. Virginia Department of Transportation Virginia
4. Virginia Transportation Research Council