Reducing Collisions Involving Young Drivers
Type of Problem Being Addressed
Young Driver Crashes
General Description of the Problem
Young drivers are more likely to be involved in a motor vehicle crash than any other age group (Williams, 2003). This is the case whether crashes are measured per population, per licensed driver, or per mile traveled. This greater crash involvement also results in additional injury risks because the youngest drivers tend to carry the largest number of passengers, typically other teens. And this group—drivers and passengers alike—is least likely to wear safety belts, thereby foregoing the best protection against injury in the event of a crash (Fell et al., 2005). Young drivers are a hazard to other road users, as well. A recent analysis showed that the majority of fatalities in crashes involving 15- to 17-year-old drivers are to persons other than the teen driver, including occupants of other vehicles and nonmotorists (American Automobile Association, 2006).
As a consequence of these factors, along with the fact that young people are infrequently affected by fatal diseases, motor vehicle crashes are by far the leading cause of death among teens in the United States, as shown in Exhibit III-1.
In 2003, 6,424 teens between the ages of 15 and 20 were killed in motor vehicle crashes (CDC, 2006). Although 15- to 20-year-olds represented 8.4 percent of the U.S. population and 6.3 percent of licensed drivers, they accounted for 13.6 percent of drivers involved in fatal motor vehicle crashes and 18 percent of drivers in police-reported crashes (NHTSA, 2005). The economic cost of crashes involving young drivers amounts to nearly 41 billion dollars a year (NHTSA, 2004).
The greater involvement of younger drivers in crashes results from a variety of factors. Especially during the first few months of driving, inexperience plays a central role in elevated crash rates. As shown in Exhibit III-2, crash rates for newly licensed drivers are highest during the first 6 months of driving, during which time they rapidly decrease. This suggests that individuals improve their driving relatively quickly. Crash rates for newly licensed drivers are substantially higher than for drivers holding a learner permit, who are only allowed to drive with an adult in the vehicle—very few learners crash while driving with a supervisor.
Cause of Death Among Persons Ages 16–20 in the United States
(U.S. Centers for Disease Control, 2006)
Crash Rates by License Status and Months of Permit/Licensure
(Mayhew, Simpson and Pak, 2003)
This lack of experience partly coincides with, and is partly responsible for, young drivers'; tendency to make poor judgments about hazards in the driving environment and hazardous actions on their own part. Although risk taking is often cited as a problem among young drivers, risky driving is the more appropriate term. Evidence suggests that deliberate risky actions account for only a small proportion of crashes (McKnight and McKnight, 2003), although they play a somewhat larger role in fatal crashes. Most crashes among the youngest drivers result from lack of awareness about what is risky, and many of the unquestionably risky actions that young drivers engage in (e.g., speeding and following too closely) result from motivations other than an explicit desire to drive in a risky manner.
Recently, attention has focused on the possible role of brain development in young driver behavior. Research suggests that the part of the brain responsible for decision making and impulse control does not fully mature until the mid 20s (Giedd, 2004). Although it is currently unknown how brain development may affect the driving behavior of young drivers, researchers are using brain imaging techniques such as magnetic resonance imaging (MRI) to study teenagers'; brains while they perform simulated driving tasks. These studies may reveal whether teenagers are cognitively able to perceive risks in the same manner as adult drivers.
Specific Attributes of the Problem
When considering strategies to reduce crashes, perhaps the most important feature of young driver crashes to consider is the substantial variation in the nature and extent of this problem within a small age range. The highest crash risk per trip, or per mile driven, is found among the youngest drivers—16-year-olds (Williams, 2003). Crash risk per mile driven declines sharply among 17-year-old drivers and drops again for 18-year-olds, although crash rates remain substantially higher than among the general driving population. The substantial differences represent a combination of factors that change rapidly among young drivers. The youngest drivers are the least experienced and the most prone to errors resulting from poor judgment; they are also the least likely to drive at all and they drive less, yet they are also more likely to carry passengers. Sixteen- and 17-year-old drivers generally live with parents and other adults and have the protections that come with this living situation. By contrast, drivers 18 and older are more likely to live outside the family home. This results in them driving more and having fewer protective constraints on their time and driving. Their crash rates per mile continue downward due to increasing experience, but their crash numbers increase as a result of greater exposure and an increase in dangerous behaviors, of which driving after drinking is perhaps the most obvious example.
One clear example of how the changing developmental stage, social milieu, and living situation contribute to increased crash risks as a teen ages is the situation with alcohol use. Alcohol-involved crashes increase from relatively low rates among 16-year-old drivers to a peak among drivers ages 20 to 24, as shown in Exhibit III-3. Although alcohol-involved crashes remain high among drivers into their mid-30s, impaired driving declines each year as individuals take on more stable jobs, marry, and begin to have children¡Xall of which entail responsibilities that conflict with a carefree lifestyle that is associated with excessive drinking.
Percentage of Drivers Involved in Fatal Crashes Who Had a Blood Alcohol Content (BAC) of 0.08 Percent or Higher by Age, 2004 (NHTSA, 2005)
Young drivers—especially 16- and 17-year-olds—are responsible for a larger number of passenger injuries and fatalities per crash than more experienced drivers. In crashes involving 16- and 17-year-old drivers, more than one-half of all fatalities occur when passengers younger than 20 are present and there is no adult in the vehicle (Williams, 2003). This results from both their greater propensity to transport several passengers and the increased likelihood of a crash that multiple passengers create. Teen passengers can be distracting to a beginning driver and may encourage the driver to take risks. One observational study of approximately 500 teen drivers found that teens drove faster and allowed shorter headways than adult drivers, especially when male teen passengers were present (Simons-Morton et al., 2005). In addition to the risks created for themselves and their passengers, young drivers also constitute a threat to other road users. One-quarter (24.2 percent) of persons killed in crashes involving 15- to 17-year-old drivers are occupants of a vehicle other than the teen';s, and another 7.5 percent are nonmotorists (e.g., a bicyclist or pedestrian) (American Automobile Association, 2006).
Nighttime driving is also associated with increased risk of serious crashes for young drivers. Among 16-year-old drivers, the risk of a fatal crash is about three times higher after 9 p.m. than during the daytime (Williams, 2003). Not all nighttime trips are high risk. Driving to and from work, for example, probably entails little risk for young drivers. However, recreational driving, which typically involves young passengers, is a substantially different—and more risky—undertaking.
Although nighttime driving can be risky, most teen driver crashes (and fatal crashes) occur during the daytime, especially during high-exposure hours just before and after school (7—8 a.m. and 3—4 p.m.). Each year, approximately 450 teens are killed and 78,000 injured in crashes during normal school travel hours (Transportation Research Board, 2002).
Fatigue can play a role in early morning crashes. Recent research on human sleep needs indicates that because of a biologically based sleep phase shift, teens begin to fall asleep later. Consequently, in order to obtain sufficient rest, they need to be asleep during the early morning (e.g., 6 a.m.) (Jenni et al., 2005; National Sleep Foundation, 2000). Later school start times are associated with fewer young driver crashes and improvements in academic performance and behavior (Danner, 2002; National Sleep Foundation, 2000)
Graduated Driver Licensing
Teenagers need driving experience in order to become proficient, savvy drivers, and therefore reasonably safe drivers. Yet the process of obtaining experience initially exposes them to great risk because of their lack of experience. Graduated driver licensing (GDL) systems address this seeming paradox in two ways. First, GDL systems have an extended learner stage, often 6 months or more, which allows beginning drivers to gain experience while driving under supervision. As shown in Exhibit III-2 above, crash rates are extremely low during the learner stage, when an adult supervisor is present. Second, GDL systems restrict newly licensed drivers from driving unsupervised in high-risk conditions, such as at nighttime or with teenage passengers.
The concept of graduated licensing has been around for several decades (Waller, 2003). Although Maryland implemented an early version of a GDL program in 1979, the modern era of graduated licensing in the United States began in 1997 with the introduction of full three-stage licensing systems in Georgia, Michigan and North Carolina. Since that time, most states have implemented a three-tiered licensing system, although the requirements and restrictions vary greatly from state to state. GDL has been highly effective in reducing crashes and fatalities among young drivers. Fatal crashes among 16-year-old drivers in the United States have decreased from a high of 31 per 100,000 population in 1995 to 23 in 2003 (NHTSA, 2005). Although encouraging, it appears the main reason for this decline is that fewer teenagers are obtaining a license while they are 16 (McKnight et al., 2002). That is, it appears that reductions in crashes and fatalities among young drivers are primarily due to decreased exposure rather than improvements in young driver behavior. There is some evidence, however, that young drivers who have been through a GDL program with a lengthy learner period exhibit lower crash rates once they begin driving without an adult supervisor (Mayhew et al., 2003).
Although young driver crashes and fatalities have decreased in recent years, young driver crash rates continue to exceed those of adult drivers. Thus, there is still a great deal of work to be done in improving young driver safety. It would be unrealistic to expect that GDL can accomplish this alone (Mayhew et al., 2006). In general, the reasons for young driver crashes are more complex than those for experienced drivers, rendering their amelioration more difficult. In addition to the factors that contribute to crashes for all drivers, there are issues of inexperience as well as matters of social, emotional, and biological development that uniquely affect young drivers.