NICHD research reveals factors that reduce crashes, including fatal crashes, among teen drivers
Car accidents are the leading cause of death and disability for adolescents. As they shift from learning to drive in classrooms and parking lots to real on-road driving situations, they encounter shifts in weather, traffic, and road conditions, as well as potential distractions.
Today's drivers encounter many possible distractions—from radios to cell phones to other passengers. Research shows that driver inattention is the primary cause of motor vehicle crashes, and that distracting tasks (such as texting) frequently cause drivers' focus to stray from the road. Reducing these distractions—especially cell phone use—is the primary message of the government agencies and other organizations that take part in Distracted Driver Awareness Month.
Because many of these situations are new to them, including how to handle distractions while driving, teen drivers are more vulnerable to accidents and injuries than are drivers at any other age. As part of its commitment to adolescent health and safety, the NICHD supports and conducts research into understanding young drivers' behavior and of ways to reduce risky driving behaviors and minimize distractions while driving.
The NICHD studies described below demonstrate a range of approaches to identifying risk factors for crashes, examining behavior and safety, and evaluating driver education and licensing programs that differ from state to state. Select a link to learn more.
Age, Gender, and Driving Risk
Research on Graduated Licensing Programs
Parental Restrictions on Teen Driving
National Distracted Driving Awareness Month and Ongoing NICHD Research on Driving
According to the Insurance Institute for Highway Safety, 16-year-olds have higher crash rates than drivers of any other age, and crash rates among teens are the highest of any age group. Understanding what makes teen drivers more vulnerable could lead to ways to reduce their risk. Researchers in the NICHD Division of Epidemiology, Statistics, & Prevention Research (DESPR) have conducted a number of studies about crash risks and risk behaviors among teen drivers. In the Naturalistic Teenage Driving Study they equipped the vehicles of 42 newly licensed Virginia drivers with recording systems to collect data during an 18-month period. These data were used to examine how conditions affected risky driving patterns as well as the likelihood of crashes.
Researchers examined data from the 42 monitored cars to determine how elevated gravitational- or "g-force" events—such as hard braking or fast acceleration―affect crash and near-crash rates among adolescents and their parents. Investigators found that adolescents were four times as likely to crash or nearly crash their cars as were the adult drivers. Teenagers' risky driving rates were five times as high as those of adults in the study. In addition, the teen crash rate declined throughout the 18-month study period, but rose slightly during the final quarter of the study. For more on this finding, visit http://www.ncbi.nlm.nih.gov/pubmed/22021319.
The researchers found that the presence of an adult passenger reduced teenage driver car crashes and near crashes by 75%. Among teens, risky driving―identified by elevated g-force events―decreased in the presence of an adult or teenage passenger, at night, and late at night. However, the researchers found that when a teen driver had risk-taking friends, risky driving and crash or near crash rates increased by 96%. Visit http://www.ncbi.nlm.nih.gov/pubmed/22098768 or listen to an audio briefing at http://www.nichd.nih.gov/news/releases/Pages/102111-teen-driving-accidents.aspx to learn more about these findings.
In a separate analysis, NICHD researchers evaluated whether elevated g-force events could be used to predict crashes and near crashes. Researchers identified elevated g-force events—such as hard turns—by evaluating video in the 42 monitored cars of newly licensed drivers. As part of their analysis, they eliminated any justified g-force events, such as swerving to avoid a pothole. Their findings showed that a pattern of elevated g-force events increased the likelihood of a car crash or near crash, especially if the g-force event occurred in the prior month. For more on this finding, visit PMID 22271924.
NICHD researchers also analyzed data from the U.S. National Household Travel Survey to determine some of the characteristics and risk factors involved with fatal teen car accidents. By examining driver sex and passenger sex and age, the researchers made some surprising discoveries. They found that young male drivers whose passengers were 16 to 20 years old had the highest risk level for fatal crash involvement. The relative risk when passengers were 21 to 34 years old was also high, particularly when both passenger and driver were male. For more on this finding, visit PMID 20159095 or http://www.nichd.nih.gov/news/releases/Pages/teen_passengers.aspx.
Other NICHD-funded research studies have examined and compared risky driving behaviors of teen girls and teen boys. Historically, teenage girls received lower insurance premiums than boys, reflecting male drivers' higher level of involvement in motor vehicle crashes. But in a 2008 review of data from fatal crashes, researchers found that female involvement in such crashes had increased over time, especially for female drivers age 20 or younger, a figure that partially reflects a large increase in the number of female drivers. Improper maneuvering and speeding were the leading causes of fatal car crashes by both male and female drivers. Alcohol use and failure to use seatbelts also played a role in fatal crashes by female drivers, although less so than did speeding and improper maneuvering. For details on this research, visit PMID 18760108.
In a 2010 NICHD-funded study, the same investigators identified gender differences in alcohol consumption as the most important factor in explaining male-female differences in non-fatal crashes. The researchers applied a hierarchical model—meaning that decisions at higher levels affected the decisions (and skills) at lower levels—to non-fatal crash data from the National Highway Traffic Safety Administration's General Estimates System (GES) for 1997 to 2007. The analysis revealed that females were less involved in non-fatal alcohol-related and speeding-related motor vehicle crashes than were males. There were no gender differences in crash rates relative to fatigue or improper maneuvering. Visit PMID 20728655 for more information on this finding.
More recently, the same group of researchers, this time funded by the National Institute on Alcohol Abuse and Alcoholism, analyzed alcohol consumption and gender as factors in car crashes. The team compared data from the U.S. Fatality Analysis Reporting System with data from U.S. National Roadside Survey and found that, for both males and females, the amount of alcohol consumed increased the likelihood of a fatal car crash. For most segments of men and women, the crash risk associated with alcohol has remained stable over time, but young females are more likely to be in alcohol-related car crashes now than they were in 1996. The analysis also showed that sober male and female young drivers were also more likely to be in fatal car crashes now than they were in 1996, an increase which the researchers believe stems from texting and other distractions. To learn more about this finding, visit PMID 22456239.
Graduated licensing programs—in which privileges are granted to new drivers in phases—are in effect in various forms in all 50 states and the District of Columbia. Researchers funded through the NICHD's Demographic and Behavioral Sciences Branch sought to evaluate the effectiveness of these graduated programs in reducing fatal crashes among teen drivers. Based on analysis of the National Highway Traffic Safety Administration's database, the researchers found that fatal crashes among 16- and 17-year-olds were reduced by 8% to 14% when these licensing limits were in effect. The greatest benefit came from restrictions on nighttime driving and on the number of teenage passengers.
Comparing the elements of graduated licensing laws in different states, the researchers also found that the most effective graduated licensing programs contained at least five of the following elements:
- A minimum age of 16 for a learner's permit
- A mandatory waiting period of at least 6 months before a driver with a learner's permit could apply for a provisional license (allows a new driver to operate a vehicle, but restricts driving conditions, such as the licensee not being allowed to drive between 11 p.m. and 5 a.m.)
- A requirement for 50 to 100 hours of supervised driving before licensure
- A minimum age of 17 for a provisional license
- Restrictions on driving at night
- Limits on the number of teenage passengers allowed in the car
- A minimum age of 18 for a full license
The researchers also found that graduated licensing laws were particularly effective at reducing alcohol-related fatalities among teens. They also found that these programs work even better when combined with other restrictions, such as mandatory seat belt laws. For details on these findings, visit PMID 21972851, PMID 22017831, PMID 22105383, or http://www.nichd.nih.gov/news/releases/Pages/110411-graduated-licensing.aspx.
NICHD research has built a considerable base of evidence supporting provisions of the national Checkpoints program—a driver education program that encourages parents to supervise their newly licensed teens and to model good driving behavior.
One important feature of the Checkpoints program, which was created by DESPR researchers, is a written agreement signed by both parents and teens. In this agreement, parents and teens commit to the conditions under which the new driver will develop good driving judgment. Learning to drive is a process of developing good judgment behind the wheel; the first six months after new drivers receive their licenses are considered the most dangerous. With a driving agreement, the parent-teen pair establishes a "checkpoint" in one month, after which they asses the new driver's comfort driving on local roads in different situations, such as when there is daylight, the roads are dry, and there are no passengers in the car. At each checkpoint, they agree to remove restrictions as long as the teen demonstrates good driving judgment. In addition, the parent commits to providing the teen rides as needed until all of the checkpoints are achieved.
Previous studies of the Checkpoints program examined whether participation influenced parental restrictions on novice teenage drivers. In one examination of the program's effectiveness, researchers compared different approaches of 469 parents and their teenage children, who had learner's permits. One-half of the families received newsletters on risky teenage driving behavior, an educational video, and a parent-teenager-driving agreement as part of the Checkpoints program. The other families received standard driving safety information. Parents who received the Checkpoint materials maintained stricter rules for when and under what conditions their teens could drive. A later study confirmed that this trend continued a full year after teens received their licenses. For details on the program, visit PMID 15727975, http://www.nichd.nih.gov/news/releases/Pages/teens_driving.aspx, or PMID 2747635.
Every April, nonprofit and government organizations unite to raise awareness about the risks of driving while distracted. Because of the alarming statistics on accidents related to cell phone or mobile device use, this year's message focuses on stopping cell phone use while driving. According to a 2006 study by researchers at Monash University, a driver is four times more likely to crash while using a hand-held device such as a cell phone. A study by the Federal Motor Carrier Safety Administration on commercial drivers found drivers up to 23 times more likely to crash while texting.
NICHD has also conducted and supported research on distracted driving—mostly among teens and novice drivers. NICHD research has demonstrated that, compared to adults, teenagers are more willing to engage in distracting secondary tasks, engage in higher rates of distracting secondary tasks, are more likely to engage in secondary tasks, more likely to crash while engaging in secondary tasks, and—even when not distracted—tend not to recognize and respond to road hazards. For example:
- One study conducted by NICHD researchers found that novice teen drivers were much more willing than were experienced adults to engage in secondary tasks such as dialing, answering the phone, changing music, texting, and the like. Both teens and adults had certain "rules" about these tasks, but adults had much more strict rules for themselves than did teens.
- Analyses of teen drivers in the Naturalistic Teenage Driving Study and of adult drivers in a U.S. Department of Transportation Study showed that reaching for objects, texting, and eating were the secondary tasks most highly associated with crashes and near crashes. Rates for each distracting secondary task were much higher for teenagers than for adults. For instance, crashes were 7 times more likely among teens dialing a cell phone, but only 2.5 times more likely among adults doing the same task (Olsen et al, 2004).
- In another NICHD study, novice teens and experienced adults drove vehicles on a test track (an actual road, but protected from traffic). As they approached a signalized intersection, the technician handed the driver a cell phone and asked him or her to dial a number and obtain certain information. When the drivers initiated the task about 200 feet from the intersection, the yellow light came on. Adults dialed a few numbers and looked up, invariably stopping at the red light. Teens tended to complete the task without looking up and many of them ran the red light. Six months later the same participants repeated the same tasks, with the same result (Olsen et al, 2006).
- In a subsequent test track study, researchers found that novice teen drivers were less likely than experienced adult drivers to notice and respond to a road hazard—in this case, a person crossing the road at an intersection, but blocked from view by a parked truck. Visit PMID 19169380 for more information on this research.
- In other NICHD-supported research, investigators from the University of Massachusetts are evaluating a unique simulation-based training program, which is designed to improve hazard detection among novice teen drivers. Visit PMID 16788108 for more on this research.
NICHD research on risk factors for crashes and ways to increase overall driving safety help to complement the awareness efforts of the U.S. Department of Transportation and other organizations. By focusing on adolescents, this research is helping to identify effective practices and interventions that keep young drivers, their passengers, and other drivers safe.
For more information on driving behavior and risk research, select one of the links below:
- Research articles discussed in this Spotlight: (Note: These are scientific documents geared toward an audience of researchers.)
- Chen, L., Baker, S.P., Li, G. (2006). Graduated Driver Licensing Programs and Fatal Crashes of 16-Year-Old Drivers: A National Evaluation. Pediatrics, 118, 56-62. PubMed ID: 16818549.
- Fell, J.C., Jones, K., Romano, E., & Voas, R. (2011). An evaluation of graduated driver licensing effects on fatal crash involvements of young drivers in the United States. Traffic Injury Prevention, 12(5), 423-431. PubMed ID: 21972851.
- Fell J.C., Todd, M., & Voas, R.B. (2011). A national evaluation of the nighttime and passenger restriction components of graduated driver licensing. Journal of Safety Research, 42(4), 283-90. PubMed ID: 22017831.
- Fisher, D.L., Pollatsek, A.P., Pradhan, A. (2006). Can novice drivers be trained to scan for information that will reduce their likelihood of a crash? Injury Prevention, 12, i25-i29. PubMed ID: 16788108.
- Kelley-Baker, T., Romano, E. (2010). Female involvement in U.S. nonfatal crashes under a three-level hierarchical crash model. Accident Analysis & Prevention, 42(6), 2007-2012. PubMed ID: 20728655.
- Klauer, S.G., Olsen, E.C.B., Simons-Morton, B.G., Dingus, T.A., Ramsey, D.J., & Ouimet, M.C. (2008). Detection of Road Hazards by Novice Teen and Experienced Adult Drivers. Transportation Research Record: Journal of the Transportation Research Board, 2078, 26-32. PubMed ID: 19169380.
- Olsen, E.C.B., Lerner, N., Perel, M., & Simons-Morton, B.G. (2004). In-Car Electronic Device Use Among Teen Drivers. Presentation at the 2005 Transportation Research Board Meeting, January 9-13, 2005, Washington, D.C.
- Olsen, E. C. B., Simons-Morton, B. G., & Lee, S. E. (2006). Novice Teen and Experienced Adult Drivers on the Smart Road Intersection: Does Six Months of Experience Matter? Proceedings of the Human Factors & Ergonomics Society 50th Annual Meeting, October 18, 8:30 AM, Hilton San Francisco Hotel, CA.
- Ouimet, M.C., Simons-Morton, B.G., Zador, P. L., Lerner, N. D., Freedman, M., Duncan, G.D., & Wang, J. (2010). Using the U.S. National Household Travel Survey to estimate the impact of passenger characteristics on young drivers' relative risk of fatal crash involvement. Accident Analysis & Prevention, 42(2), 689-694. PubMed ID: 20159095.
- Romano, E., Fell, J., & Voas, R. (2011). The role of race and ethnicity on the effect of graduated driver licensing laws in the United States. Annals of Advances in Automotive Medicine, 55, 51-61. PubMed ID: 22105383.
- Romano, E., Kelley-Baker, T., Voas, R.B. (2008). Female involvement in fatal crashes: increasingly riskier or increasingly exposed? Accident Analysis & Prevention, 40(5), 1781-8. PubMed ID: 18760108.
- Simons-Morton, B.G., Hartos, J.L., Leaf, W.A., & Preusser, D.F. (2005). Persistence of effects of the Checkpoints Program on parental restrictions of teen driving privileges. American Journal of Public Health, 95(3), 447-452. PubMed ID: 15727975.
- Simons-Morton, B.G., Ouimet, M.C., Zhang, Z, Klauer, S.E., Lee, S.E., Wang, J., Albert, P.S., & Dingus, T.A. (2011). Crash and risky driving involvement among novice adolescent drivers and their parents. American Journal of Public Health, 101(12), 2362-2367. PubMed ID: 22021319.
- Simons-Morton, B.G., Ouimet, M.C., Zhang, Z., Klauer, S.E., Lee, S.E., Wang, J., Chen, R., Albert, P., & Dingus, T.A. (2011). The effect of passengers and risk-taking friends on risky driving and crashes/near crashes among novice teenagers. Journal of Adolescent Health, 49, 587-593. PubMed ID: 22098768.
- Simons-Morton, B.G., Zhang, Z., Jackson, J.C., & Albert, P.S. (2012). Do elevated gravitational-force events while driving predict crashes and near crashes? American Journal of Epidemiology Advance Access, [Epub ahead of print], 1-5. PubMed ID: 22271924.
- Voas, R. B., Torres, P., Romano, E., & Lacey, J. (2012). Alcohol-Related Risk of Driver Fatalities: An Update Using 2007 Data. Journal of Studies on Alcohol and Drugs, 73(3), 341-50. PubMed ID: 22456239.
- Zakrajsek, J.S., Shope, J.T., Ouimet, M.C., Wang, J., & Simons-Morton, B.G. (2009). Efficacy of a Brief Group Parent–Teen Intervention in Driver Education to Reduce Teenage Driver Injury Risk A Pilot Study. Family & Community Health, 32(2), 175-188. PubMed ID: 2747635.
- NICHD Resources
- Checkpoints Program Web Site
- U.S. Department of Transportation:
- Centers for Disease Control and Prevention: Teen Drivers
Originally posted: April 23, 2012