August 27, 2010
TEEN DRIVING BEHAVIOR
By: Paul Frisman, Principal Analyst
You asked how the presence of passengers, especially teenage passengers, affects teenage drivers. You also asked about the effect of having a parent and young sibling accompany a teen driver.
Numerous studies show that teenage drivers transporting teenage passengers have a higher risk of fatal crashes than do teenagers driving alone or with older passengers. Researchers attribute this to inexperience, risk-taking behavior, and peer pressure, among other factors. Recent research also cites physiological reasons: studies have shown that adolescent brains are still developing and may not yet be able to adequately control impulsive behavior.
Forty-nine states have adopted some form of three-stage, graduated driver licensing (GDL) programs to reduce teenage driving crashes and deaths. The programs phase in full driving privileges for teenagers over time based on the degree of risk. Typically, these programs limit the hours teenage drivers may drive and the number of passengers (except for family members or driving instructors) they may carry. Studies of these programs have found that they are effective in reducing teen driver crash deaths.
We were unable to find studies on how transporting a parent and sibling affects teen driving behavior. The national Transportation Research Board has said that this is one of several areas requiring more study.
BACKGROUND: TEEN FATAL CRASH RATE
Motor vehicle crashes are the leading cause of death for teenagers aged 15 to 20. According to the National Highway Traffic Safety Administration (NHTSA) 2,739 drivers aged 15 to 20 were killed and 228,000 injured in motor vehicle crashes in 2008 (http://www-nrd.nhtsa.dot.gov/pubs/811169.pdf). The Insurance Institute for Highway Safety states that the crash rate per mile among drivers aged 16 to 19 is four times as high as for older drivers (http://www.iihs.org/externaldata/srdata/docs/sr4507.pdf).
Young teen drivers also put others at risk. A 2006 AAA study found that most of the fatalities in crashes involving 15-to-17-year-old drivers were people other than the driver: 31.8% of those killed were passengers in the teen driver's vehicle; 24.2% were occupants of vehicles operated by drivers age 18 or older, and 7.5% were non-motorists, such as pedestrians and bicyclists (http://www.aaafoundation.org/pdf/ReducingTeenCrashes.pdf).
TEENAGE DRIVING BEHAVIOR
Incidents of Teenagers Dying in Motor Vehicle Crashes When Accompanied by Teenage Passengers
Researchers studying teen driving behavior have analyzed federal and other accident statistics, observed driver behavior, and surveyed teen drivers. The factors they examined include risk-taking behavior of teen drivers and the presence of passengers, especially teenage passengers, in their vehicles.
Numerous analyses of federal accident reporting data and other sources have found that teen drivers are more likely to be involved in crashes when driving teenage passengers. Among other things, these analyses show that:
● in fatal crashes involving 16- and 17-year-old drivers who did not have an adult in the car, more than half (55%) had a passenger younger then age 20;
● 63% of the deaths of 13- to 19-year-old passengers in 2000 occurred when other teenagers were driving;
● teenage drivers who have two or more teenage passengers are at particularly high risk of fatal crashes; and
● carrying young male passengers has a particularly high risk of fatal crashes (Passenger Distractions among Adolescent Drivers, Journal of Safety Research, 39 (2008) 437-443, (attached)).
It appears that teenage drivers' risk-taking behavior depends in part on the vehicle's passengers. A 1997 study noted that teen drivers “can be extremely safe drivers…when learning to drive with their parents or some other adult” but that “young drivers will take risks behind the wheel in some driving contexts that they would not take in other contexts” (The Effect of Teenage Passengers on the Fatal Crash Risk of Teenage Drivers, Analysis and Prevention, Vol. 30, No. 2 (attached)).
One investigation of the effect of teenage passengers on risky driving behavior found that teenage drivers were more likely than adult drivers to drive faster and follow other vehicles more closely, especially when teenage boys were passengers (The Observed Effects of Teenage Passengers on the Risky Driving Behavior of Teenage Drivers, Accident Analysis and Prevention, 2005).
Effects of the Number of Passengers Accompanying a Teen Driver
One study found accident rates for 16-19 year olds “increased considerably when passengers were present…In most cases collision rates were approximately twice as high with passengers as without passengers…The involvement rates were found to be lowest for zero passengers, increased substantially when one passenger was present, and increased even more when two or more passengers were present” (The Situational Risks of Young Drivers: The Influence of Passengers, Time of Day, and Day of Week on Accident Rates, Accident Analysis and Prevention, Vol. 30, No. 1 (1998)).
A 2000 study noted that the presence of passengers affected teen drivers and older drivers differently. That study found that the incidence of motor vehicle crashes in which a 16- or 17-year-old driver was killed increased with the number of passengers. In contrast, death rates for drivers between ages 30 and 59 were lower for drivers with passengers than for those driving alone.
The highest death rate was observed among 16-year-old drivers with three or more passengers. “Crashes are more likely to be fatal to drivers aged 16 and 17 years in the presence of male passengers, teenaged passengers, and passengers aged 20 to 29 years,” the researchers found. The researchers also noted that a survey of 192 high school drivers found that dangerous driving behaviors (driving after drinking alcohol or using drugs, speeding, swerving, crossing the center line, purposely skidding, and running a red light) were strongly associated with the presence of other teens (Carrying Passengers as a Risk Factor for Crashes Fatal to 16- and 17-Year Old Drivers, Journal of the American Medical Association, March 22/29, 2000, Vol. 283, No. 12).
“The excess risk attributable to passengers appears specific to the teenage years,” said researchers in another study. “In one study comparing drivers ages 16-19 to those in their 20s, the teenage drivers, but not the drivers in their 20s, experienced higher crash rates when they carried passengers. In addition and in contrast to the excess risk seen with carrying teenage passengers, carrying older passengers is associated with a reduction in crash risk” (Passenger Distractions among Adolescent Drivers, Journal of Safety Research, 39 (2008) 437-443, (attached)).
Effect of the Age of Passengers on Teen Drivers
Studies show that the age of a teen driver's passengers, as well as their number, increases the likelihood that the drivers will be involved in accidents and fatal crashes.
A 1999 study found that young drivers are least likely to cause single- or two-vehicle accidents when traveling with adults or children, but have “an increased propensity for causing single-vehicle accidents when traveling with peers…The results suggest that risk-taking is a factor… in young driver safety.” (Impact of Passengers on Young Driver Safety, Transportation Research Record, Vol. 1693/1999, (attached)).
Another study found that the death rate for 16- and 17-year-old drivers transporting only passengers younger than 20 was more than three times the rate for 16- and 17-year-old drivers without passengers, and nearly four times the rate for drivers age 18 or older carrying any passengers (Potential Benefits of Restrictions on the Transport of Teenage Passengers by 16 and 17-year-old Drivers, Injury Prevention 2001; 7-129).
“Overall,” another report found, “16-year-old drivers, compared with drivers of other ages, were most likely to have been accompanied by one or more passengers at the time of their fatal crash involvement…The results of this study indicate that the risk of being involved in a fatal crash is much higher for teenage drivers when passengers are present in the vehicle as compared with driving alone, particularly when the passengers are other teenagers and particularly when more than one teenage passenger is present” (The Effect of Teenage Passengers on the Fatal Crash Risk of Teenage Drivers, Accident Analysis and Prevention, Vol. 30, No. 2).
Surveys of teenagers show that they are well aware of the hazards of driving with teenage passengers, or being a passenger in a vehicle driven by a peer. Eighty-five percent of teen drivers, when surveyed about their most dangerous driving situation in the previous six months, cited events involving peers in their vehicles. Fifty-nine percent reported having been a passenger when a friend drove dangerously.
Peers play a vital role during this time, researchers noted, because “driving with peers is a highly desirable activity for 16- and 17-year-olds, affording them status, peer approval, and independence.” Parents also play an important role, but the report said that parents “often do not appreciate the danger involved in driving with peers, and…find it difficult to enforce driving rules and restrictions” (Passenger Distractions among Adolescent Drivers).
The researchers in this study surveyed 2,144 California high school seniors in 2006. They found among other things, that 38.4% of young drivers reported they had been distracted while driving by one or more of their passengers. Of these:
● 45% said their passenger talked, yelled, argued, or were simply loud;
● 22% said their passengers distracted them by “fooling around,” “messing around,” “being stupid,” wrestling, or throwing things from the car windows; and
● 7.5% said their passengers intentionally distracted them by punching or tickling them, throwing things at them, or trying to grab the wheel or other vehicle controls.
The survey did not ask the age of the passengers, but most of the respondents who identified the passenger said it was either a friend or sibling. (However, some students said they were distracted by a parent talking, joking, lecturing, arguing with, or yelling at, them.)
The researchers concluded that teenage passengers “frequently encourage or create dangerous situations for the driver.” They said that while conducting driver education programs focusing on these risks could be beneficial, “high-risk passenger behavior may be a developmental norm that education might have a difficult time combating.”
The researchers state that physiological reasons may play a role in teens' risk-taking behavior. Recent studies have shown that brain development continues through adolescence. “The less developed [brain] pathways of adolescents may explain why they are more likely to exhibit risky behavior…[R]isk taking during adolescence is the product of an interaction between heightened stimulation seeking and an immature self-regulatory system that is not yet able to control impulses.”
The researchers suggested that providing parents with better information about the risks associated with teenage passengers, and encouraging parents to enforce GDL laws, could help reduce the frequency of teenage passengers distracting teen drivers.
EFFECTS OF GRADUATED LICENSING PROGRAMS
Almost all states now require teenage drivers to obtain their full driving privileges in stages – typically a learner's permit stage that includes supervised driving and an intermediate stage with restrictions on passengers and nighttime driving – before obtaining full driving privileges. Research has shown these GDL programs are effective in reducing crashes among the youngest drivers.
“Recent research suggests that we have seen significant progress in the United States toward reducing fatal crashes per population among 16-year-old drivers,” researchers said, citing a 2005 study finding that crashes per population declined more for 16-year-old drivers than for drivers of other ages (Progress in Teenage Crash Risk During the Last Decade, Journal of Safety Research 38 (2007)).
The authors said the beneficial effect of GDL passenger restrictions could be seen in statistics showing that “between 1996 and 2005, fatal crashes involving 16-year-old drivers decreased 37% overall.”
They noted the largest reductions occurred for fatal crashes involving passengers. “Fatal crashes involving teenage passengers decreased 41%, and crashes involving passengers of other ages decreased 49%. Furthermore, the percent of fatal crashes involving 16-year-olds carrying three or more passengers was reduced by half,” they said.
MORE RESEARCH NEEDED ON RELATIVES IN CAR
The national Transportation Research Board's Subcommittee on Young Drivers identified “passenger issues” as one of five critical research needs in a June, 2009 report. “Passenger restrictions are not currently based on a thorough understanding of how passenger presence increases the likelihood of teenager driver crashes,” the board said in Future Directions for Research on Motor Vehicle Crashes and Injuries Involving Teenage Drivers (attached). “Nor is there any understanding of whether, or how, young family members – who are generally exempted from GDL passenger limits – influence crash risks for teenage drivers. Both observational and experimental research on this topic is greatly needed.”