IIHS Advisories | No. 6, August 1988
Drivers' crash, violation records predict future crash involvement
As a group, drivers who have traffic law violations or crashes on their driving records have much higher subsequent crash involvement rates than drivers with clean driving records. This is the principal finding of the California Department of Motor Vehicles' latest analysis of the driving records of more than 160,000 licensed drivers in that state during 1980-82.
The report's findings "provide some support for the practice of graduating auto insurance premiums based on the driving record," according to the authors. "Traffic conviction frequency is a more valid actuarial risk factor than prior accident frequency, and the sum of the two is better than either alone."
California drivers involved in two crashes during a three-year period have 2.3 times as many crashes in the next three years as drivers with no prior crashes. Drivers with eight or more points on their licenses in a three-year period have 4.1 times as many crashes in the next three years as drivers with no points. Similar patterns have been reported for drivers in North Carolina as well as for Maryland and Washington State drivers involved in fatal crashes.
In California, crashes and violations are represented as points on drivers' licenses. One point is entered on the driving record for each routine moving-violation conviction. One point is entered for each crash for which the driver is deemed responsible. More points are charged for serious offenses such as driving under the influence of alcohol or drugs. A California driver who has accumulated four or more license points in one year, six or more in two years, or eight or more points in three years is termed a "negligent operator." Drivers classified as negligent during a two-year period (i.e., six or more points on their licenses) represent less than one percent of all drivers licensed in California, but they are involved in six percent of all crashes. Drivers with two or more crashes in a three-year period represent two percent of all drivers licensed in California, but they are involved in about seven percent of all crashes.
Most Drivers Have Clean Records…
Most of California's licensed drivers aren't negligent. They have very good records, according to the report. Sixty-three percent of them don't have any points charged against their licenses. Sixty-eight percent of them have no record or driving offenses during a given three-year period. And 87 percent have no record of crash involvement during a three-year period.
Many Californians' driving may not be as error-free as their records indicate. More than 25 percent of those who get tickets for traffic violations choose to complete eight hours of classroom instruction in order to get points removed from their licenses. The problem is, the classes probably don't make people drive more safely. With names like Laff 'n Learn, Lunch 'n Learn, and LA Singles Traffic School, much of the instruction has become secondary to amusement.
Officials at California's Department of Motor Vehicles have "no illusions about the efficacy of sending traffic violators to school. Reviewing traffic laws is not going to change the hard core traffic violator's modus operandi." Yet the schools proliferate — there are more than 300 of them across the state — and 800,000 Californians attend them every year in order to keep traffic violations off their driving records.
No Silver Bullet
Despite the clear overrespresentation of repeat offenders in crashes, the authors of the California report caution that "it would be incorrect to conclude that the majority of accidents are caused by a small number of 'accident-prone' drivers or that individual accident involvement can be predicted with a high degree of precision. The majority of accidents in any time period involve drivers with average or good prior driving records."
A third of all crashes in any given year in California involve drivers with no points at all on their licenses. Two-thirds involve drivers who have no crashes recorded during the preceding three years. Thus, the report concludes, selective targeting of negligent drivers "can never constitute a 'silver bullet' through which the majority of all accidents can be prevented."
For further information, see "Basic California Traffic Conviction and Accident Record Facts" by Michael A. Gebers and Raymond C. Peck, California Department of Motor Vehicles, Research and Development Section (December 1987).
|Relationship Between Driving Records and Subsequent Crash Likelihood|
|Prior 3 years, 1977-79||Subsequent 3 years, 1980-82|
|Number of crashes on driving record||Times as likely to crash|
|Number of points on driving record||Times as likely to crash|
|Number of convictions on driving record||Times as likely to crash|