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Matt Nagle
Center for Criminal Justice Research

Liz Joss
School of Public and Environmental Affairs

Last modified: Tuesday, March 15, 2011

IU report: State law limiting teen driving reduces crashes

March 15, 2011

INDIANAPOLIS -- Indiana's increased restrictions on teen drivers have resulted in a steep reduction in car accidents involving young drivers, according to a new analysis of crash data by the Indiana Public Policy Institute. The report, "Effects of Graduated Driver Licensing on Crash Outcomes in Indiana," finds there were hundreds fewer accidents as a result of restrictions that took effect in July 2010.

"This area is a prime example of data-driven policy, in that we knew intuitively that teens were problem drivers, but without analyzing crash and tickets data, we couldn't identify the most effective way of responding," said Matt Nagle, senior policy analyst with the institute and the report's author. "With this study and with others that will follow, we can evaluate the effects of the graduated license law and use the research to inform discussions about future improvements in the law and its enforcement."

Findings include:

  • Crashes involving young drivers dropped sharply after the state raised the minimum age for getting a driving license or permit.
  • Restrictions did not appear to reduce accidents by teens driving late at night or with passengers in the vehicle.
  • Crashes involving young drivers using cell phones declined after a ban took effect.

The report was produced by the Center for Criminal Justice Research, part of the Indiana Public Policy Institute at Indiana University-Purdue University Indianapolis. The center, within the IU School of Public and Environmental Affairs, provides applied research that leads to better solutions to policy issues.

Young Driver

Creative Commons photo by Dave Parker

The Center plays a key policy role in this process by providing analyses on crash rates, examining alternative methods of reducing crashes from other states and research by national organizations, and now by evaluating the effectiveness of the state law.

The law took effect in two phases. Starting in July 2009, newly licensed young drivers faced restrictions on late-night driving and driving with passengers, and cell phone use was banned for drivers under 18. In July 2010, the law raised the age at which teens could get permits or licenses and lengthened the wait between getting a permit and getting a license.

Teens used to qualify for a license at 16 years, one month, if they completed a driver's education course and at 16 years, six months if they hadn't. Now the minimum age is 16 years, six months with driver's education and 16 years, nine months without.

The second phase reduced accidents, the report shows, thanks to a decrease in the number of licensed young drivers. Relying on an analysis of police-reported crash data, the IU report shows that, as a share of all drivers involved in crashes, teenage drivers decreased from just less than 6 percent in the second quarter of 2010 to 4.5 percent in the fourth quarter. In the second half of 2010, there were about 400 fewer crashes involving drivers in the 16- to 16-1/2-year-old age range than would have been expected from historical trends.

But there was little evidence of safety improvements from some of the requirements that took effect in 2009. The incidence of young drivers in crashes with passengers in the vehicle has remained relatively constant even though newly licensed young drivers are generally prohibited from having young passengers. Also, the share of late-night crashes involving 16-year-old drivers has remained at historical levels despite a law barring newly licensed young drivers from driving late at night.

"Unless law enforcement was strong enough to bring about changes in driving behavior, there may not have been enough motivation for teen drivers to alter driving times and to drive without young passengers," the report says.

The ban on cell-phone use by young drivers may have had an effect, however. Drivers under 18 who crashed while using cell phones declined from 0.71 percent to 0.56 percent. The report says the decline is noteworthy because police may be more likely to report cell phone use now that it's illegal.

Finally, more time is needed to evaluate the third way in which the graduated driving license law is intended to reduce crashes -- by reducing the extent to which the youth and inexperience of very young drivers cause them to engage in more risk-taking behaviors. It will take six to 12 months longer to develop enough crash data to evaluate whether older teenager drivers are safer drivers, the report says.

The full report is available online at

The IU Public Policy Institute, established in 2008, is a collaborative, multidisciplinary research institute that delivers research, service and consulting on vital issues facing policy leaders. It serves as an umbrella for research centers affiliated the School of Public and Environmental Affairs, including the Center for Urban Policy and the Environment, and the Center for Criminal Justice Research. For more information see