As teens delay driver licensing, they miss key safety instruction

In a study in the July 2 edition of the Journal of Adolescent Health, researchers at Yale identified some of the factors contributing to delaying driving licensure, or DDL, and pointed to policy changes that could expand safety training regardless of age.

When teens delay getting their driver's licenses, said lead author Dr. Federico E. Vaca, professor of emergency medicine and director of the Yale Developmental Neurocognitive Driving Simulation Research Center (DrivSim Lab), they age out of these safety measures which are not required after a person turns 18. "On the day I turned 16, I was at the DMV getting my license," said Vaca. "Now, that's not happening. We wanted to know, why not?"

The study found that race, socioeconomic status, and parenting are all important factors.

From 2006 to 2016, the proportion of high school seniors with driver's licenses fell from 81% to 72%, and at least 70% of eligible adolescents delay licensing by at least one year, the study noted. These delays affect the extent to which these young drivers participate a program known as Graduated Driver Licensing (GDL), requirements that young drivers must meet before they have a fully independent license. The GDL program, some version of which exists in all 50 states, typically requires 16-year-olds to log a certain number of hours of practice driving with a parent or guardian during a learner's permit stage, and later restricts late-night driving and driving with young passengers. Many states also include restrictions on cell phone use in the car as part of the GDL.

"These are key restrictions," said Vaca. "All the epidemiology shows that the later you drive at night, the more dangerous it is. "Once you get past 9 or 10 p.m., the fatal crash rate goes up. We also know from the literature that, for young drivers, the risk of fatal crashes also goes up with the number of passengers in the car."

GDL addresses these facts, and the programs have been successful in promoting safer driving, Vaca said. After GDL programs were introduced in the U.S. in the mid-nineties, fatal crashes among teens declined by 74% among 16-year-olds, by 61% among 17-year-olds, by 55% among 18-year-olds, and by 45% among 19-year-olds.

The researchers found that certain racial, ethnic, and socioeconomic groups are delaying licensure at higher rates -- in particular Latino and black teens. Using data from the National Institutes of Health's NEXT Generation Health Study, which followed a cohort of 10th grade students into adulthood, the Yale researchers found that Latino teens were 4.5 times as likely as white teens to delay getting their licenses by over two years and black teens were 2.3 times as likely.

Furthermore, they found that teens whose parents' highest educational degree level was high school were 3.7 times more likely to delay by over two years than those whose parents had a college degree. Teens from poor families were 4.4 times as likely to delay for more than two years compared to those from affluent families. Teens who perceived that their mothers were actively involved in their lives and monitoring their behaviors were less likely to delay their driving licensure. A similar effect was not seen with fathers.

When young people don't start driving until their early 20s, said Vaca, they are navigating a much more complicated world, where exposure to alcohol and drugs -- a major contributor to crash risk -- is considerably higher than for teens.

"If you haven't gone through GDL, you're not gradually exposed to nighttime driving and typically not gradually exposed to driving with several passengers where you progressively learn to manage the occupant space while driving," Vaca said.

Vaca said that in addition to missing safety instruction, which results in more crashes and fatalities among vulnerable populations, some teens who delay licensure miss out on employment, education, and other opportunities.

One solution, Vaca said, can be found by looking to GDL policies in other countries, such as Australia and the United Kingdom, where GDL restrictions are applied to novice drivers of all ages before a full license is issued.

"Motor vehicle crashes are the leading cause of death for young people," Vaca said. "It's important that they get sufficient supervised practice driving as well as gradual exposure to a variety of driving conditions and learn how to safely navigate them."