September 14, 2011
Restrictions Do Little To Prevent Fatal Crashes
Tougher state laws that have placed restrictions on teenage driving, requiring them to “graduate” from an intermediate license to a full license have seemed to prevent fatal crashes involving teens, but only among the youngest drivers, according to a study in the Journal of the American Medical Association (JAMA).
The study showed that restricting nighttime driving and number of passengers in a car were associated with a lower incidence of fatal crashes among 16-year-old drivers, but a higher incidence among 18-year-old drivers.
The new analysis of national crash data found that between 1986 and 2007, the rate of fatal traffic accidents involving 16-year-old drivers was 26 percent lower in the states that adopted the restrictions, compared to states without either restriction.
Among 18-year-olds, the restrictions were associated with a 12 percent increase in the fatal crash rate, which effectively canceled out the benefits among younger drivers. When teens drivers of all ages were grouped together, the link between the graduated driver licensing (GDL) programs and the rate of fatal crashes was statistically unimpressive.
“Right now, we're not getting the net effect across all teens that we're hoping for,” said Scott V. Masten, Ph.D., the lead author of the study and a researcher at the California Department of Motor Vehicles, in Sacramento, according to various media reports. “We're getting this washout where we do save some lives overall, but not nearly what we thought it [would be].”
Many states require young drivers to go through extensive training before getting a full license, but most states only require it of those under 18 years of age.
The new study suggests some teens are putting off getting their license until they turn 18 -- meaning they have less experience behind the wheel and higher odds of a fatal crash.
In a nationwide survey of almost 1,400 teens published last month in the journal Traffic Injury Prevention, one in four 18-year-olds who hadn't obtained a license cited the hassle of licensing requirements was a reason they refrained from getting their license at a younger age.
“There's an incentive right now to skip out and just wait until you're 18,” Masten told the Associated Press (AP). “In most states you don't even need to have driver education or driver training” if you obtain a license at 18, he said.
“I was actually bummed by my own findings -- to find out we're offsetting the benefits” in young drivers so much, he said. “It was quite unexpected.”
Most previous studies have also linked GDL programs with a decline in fatal crash rates among young teens, but evidence on effects in older teens is mixed at best.
Masten and his colleagues cannot explain the increase in traffic deaths among 18-year-olds, but suggest that it may be a form of “payback” for the restrictions on younger drivers. By limiting teen driving GDL laws may deprive younger teens of valuable driving experience.
GDL programs are now in force in all 50 states in one form or another. Every state requires would-be teen drivers to first get a learner´s permit, during which they can drive only with adult supervision, but beyond that the strength of the programs vary.
For the purposes of their study, Masten´s team considered GDL programs that prohibit teens from driving after 1 a.m. and carrying certain passengers to be “stronger,” while they considered programs with just one of these restrictions to be “weaker.”
They analyzed fatal crash data from the National Highway Traffic Safety Administration and information on each state´s licensing programs.
The researchers estimated that since the first GDL program went into place in 1996, they have been associated with 1,348 fewer fatal crashes involving 16-year-old drivers but with 1,086 more fatal crashes involving 18-year-old drivers.
During the 21-year-long study, the researchers found there were nearly 132,000 fatal crashes involving drivers aged 16 to 19. Nearly 20 percent involved 16-year-old drivers and 30 percent involved 18-year-old drivers.
Masten said more research is needed to determine why fatal crash rates among 18-year-olds rose and whether an increase also occurred in nonfatal crashes.
The study does confirm that GDL programs are doing what they are supposed to do, which is “prevent novice drivers from being in high-risk conditions before they're ready for it,” Dr. Flaura Winston, a pediatrician and traffic injury expert at the Children's Hospital of Philadelphia, told the AP. But the results also show there's a need for strategies for the novice independent driver at any age, she said.
“Motor vehicle crashes are the leading cause of death in the United States for teenagers. From 2000-2008, more than 23,000 drivers, and 14,000 passengers aged 16 to 19 years were killed,” according to background information in the study. “Graduated driver licensing is structured to ensure that young novices gain extensive experience driving in low-risk conditions before they ℠graduate´ in steps to driving in riskier conditions.”
In an accompanying editorial from the IHS, Anne T. McCartt, Ph.D., and Eric R. Teoh, M.S., wrote that the results of this and other studies, taken together, strongly support the benefits of GDL in the youngest of drivers.
“In the United States, depending on state law, graduated driver licensing programs have been directed primarily at 16-year-olds and, to a lesser extent, 15- and 17-year-olds, and most evaluations have focused on these ages,” they wrote.
“Moreover, as discussed by Masten et al, there are various ways in which graduated driver licensing may negatively affect 18- and 19-year-olds. There currently is no empirically validated explanation for effects of graduated driver licensing, positive or negative, on older teenagers. To the extent that some of the positive effects at earlier ages may be blunted, this is a serious issue deserving attention by researchers and policy makers. It is likely that further reductions in crashes involving young drivers can be achieved by strengthening individual components of licensing laws,” wrote McCartt and Teoh.
They noted that New Jersey is one of the few states that has adopted GDL restrictions to include all first-time applicants under the age of 21. That has led to lower crash rates among the 17- to 18-year-old age group.
Whether these programs should be extended to include older teens warrants further study, the IHS researchers wrote in the editorial.
On the Net:
- JAMA Abstract
- California Department of Motor Vehicles
- Traffic Injury Prevention
- National Highway Traffic Safety Administration