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Progress in teenage crash risk during the last decade
Journal of Safety Research 38 (2007) 137 – 145
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Progress in teenage crash risk during the last decade Susan A. Ferguson a,⁎, Eric R. Teoh b , Anne T. McCartt b a
b
Ferguson International LLC, 1328 Lancia Drive, McLean, VA 22102, USA Insurance Institute for Highway Safety, 1005 North Glebe Road, Arlington, VA 22201, USA Available online 28 March 2007
Abstract Objective: The purpose of the present study was to examine the most recent data on teenagers' fatal and nonfatal crashes in the United States to determine current crash rates as well as changes in crash rates during the past decade Methods: Data for calendar years 1996 and 2005 were extracted for fatal crashes from the Fatality Analysis Reporting System and for police-reported crashes from the National Automotive Sampling System/General Estimates System. To calculate crash rates, population data were obtained from the Census Bureau, and mileage data were obtained from the 2001 National Household Travel Survey Results: During 2001–02, the latest year for which mileage data are available, 16 year-old drivers had higher fatal and nonfatal crash rates per mile traveled than all but the very oldest drivers. However, fewer 16 year-olds typically are licensed to drive and they drive fewer miles per year than all but the oldest drivers. Thus, their fatal and nonfatal crash rates per population in 2005 were lower than among other teenagers and among drivers 20–29. During the past decade the most progress has been made in reducing crashes among the youngest drivers. Between 1996 and 2005 both fatal and police-reported crashes per population declined about 40% for 16 year-old drivers, compared with about 25% for 17 year-old drivers and 15–19% for 18 year-old drivers. The greatest reductions for 16 year-olds occurred in nighttime crashes, alcohol-related fatal crashes, and fatal crashes involving multiple teenage passengers. Conclusions: Substantial progress has been made in reducing fatal and nonfatal crashes per population among 16 year-old drivers. Although this study was not designed to examine the role of graduated licensing, the results are consistent with the increased presence of such laws, many of which restrict nighttime driving and driving with teenage passengers. Impact on Industry: Restrictions on nighttime driving and driving with teenage passengers should be made a part of all states’ graduated licensing systems. Historically, 16 year-olds have had the highest crash risk per licensed driver and per mile traveled. Given the dramatic reductions in per population crash rates among 16 year-olds, it is possible that their per mile and per licensed driver rates also have declined and may no longer be as elevated relative to other ages. However, shortcomings in the licensed driver data and a lack of recent mileage data hamper our ability to examine these issues. If we are to continue to provide a yardstick against which we can measure progress among the youngest drivers, immediate steps need to be taken to restore the availability of reliable exposure data. © 2007 National Safety Council and Elsevier Ltd. All rights reserved.
1. Introduction Teenage drivers, especially 16 year-olds, have long been considered to pose the greatest risk to themselves and other road users, and for good reason. Historically, their fatal crashes per mile traveled and per licensed driver have been higher than for all but the very oldest drivers (Li, Braver, & Chen, 2003; Lyman, Ferguson, Braver, & Williams, 2002). Beginning drivers of all ages have higher crash rates than drivers with more experience, but the youngest drivers are known to take addi-
⁎ Corresponding author. Tel.: +1 703 847 5317. E-mail address: [email protected] (S.A. Ferguson).
tional risks because of youthful exuberance and immaturity (Mayhew, Simpson, & Pak, 2003). Teenage crash risk is particularly elevated when driving at night and when carrying teenage passengers (Chen, Baker, Braver, & Li, 2000; Doherty, Andrey, & MacGregor, 1998; Preusser, Ferguson, & Williams, 1998; Ulmer, Williams, & Preusser, 1997; Williams, 2003; Williams, Ferguson, & Wells, 2005). Legislators in many states have tried to address these concerns through the adoption of graduated driver licensing (GDL) laws. Starting with Florida in 1996, U.S. states have modified their laws requiring beginning drivers to complete a series of stages before obtaining full-privilege licenses. The majority of states now have some form of graduated licensing. Typically after a learner's permit period of at least 6 months,
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teenagers are given restricted licenses that often prohibit driving unsupervised at night or carrying one or more teenage passengers (Insurance Institute for Highway Safety [IIHS], 2006a). Once these stages have been negotiated successfully, teenagers can obtain unrestricted licenses. Research examining the effectiveness of graduated licensing at the state level, as well as comprehensive evaluations of national fatal crash data, have demonstrated consistently that GDL programs are effective in reducing crashes among the youngest drivers (see Shope, 2007). Williams (2003) examined crash data from 2000 and crash rates per mile traveled from 1995 to compare the crash risk of teenage drivers with that of drivers of other ages. He concluded, “On most measures, crash rates during the teenage years are higher than for any other age, for both males and females.” To the extent possible the present paper will answer the question of whether this conclusion still is true. Recent research suggests that we have seen significant progress in the United States toward reducing fatal crashes per population among 16 year-old drivers. Williams et al. (2005) found that crashes per population declined more for 16 year-old drivers than for drivers of other ages. Between 1993 and 2003, fatal crashes per population declined 26% for 16 year-old drivers, 11% for 17 year-old drivers, 6% for 18–19 year olds, and 7% for drivers ages 20–49. There were few differences over time in the percentages of fatal crashes that occurred at night, or involved single vehicles, driver error, or speeding. However, the proportion of fatal crashes in which 16-year-old drivers were transporting only teenage passengers decreased from 53% in 1993 to 44% in 2003. The present paper provides updated information on teenage driver crash rates, including rates for fatal and nonfatal crashes. Ideally, a comprehensive evaluation of crash rates and crash rate trends would include calculations per population, per licensed driver, and per mile traveled. However, examination of annual state-by-state counts of licensed drivers published by the Federal Highway Administration revealed that teenage drivers have been undercounted in some states for the past several years (Insurance Institute for Highway Safety, 2006b). Researchers found large year-to-year differences in licensed driver counts in a number of states, and these differences could not be explained by fluctuations in population or changes in state licensing laws. The IIHS concluded that these current and historical data do not provide reliable measures of the number of licensed drivers, especially the youngest ones. 2. Methods Teenage drivers' crash risk, for both fatal and nonfatal crashes, was examined using the latest available data from a variety of sources. In-depth mileage data were obtained from the National Household Travel Survey (NHTS), formerly the Nationwide Personal Transportation Survey. NHTS collects mileage data from a sample of drivers of all ages, including data on travel at different times of the day. Samples can be weighted to provide national estimates. Surveys typically are
conducted about every 5 years, but the latest survey was conducted during April 2001–May 2002. Data on fatal crashes were obtained from the Fatality Analysis Reporting System (FARS). FARS is a virtual census of fatal motor vehicle crashes that occur on public roads in the United States in which vehicle occupants or other road users die within 30 days of a crash. Data on police-reported crashes were obtained from the National Automotive Sampling System/General Estimates System (NASS/GES). NASS/ GES contains a representative sample of U.S. police-reported crashes that can be weighted to provide national estimates. Crashes were examined as a function of driver gender and age. Fatal crash characteristics examined included driver error, speeding, crash type, and drivers' blood alcohol concentrations (BAC). The definition of driver error was based on driver-related factors coded in FARS and was intended to capture the physical movements of the vehicle that were clearly indicative of driver mistakes (e.g., improper lane change, passing on the wrong side, overcorrecting). Codes for driver physical/mental conditions such as inattention, drowsiness, or alcohol impairment were excluded. Speeding was defined to include cases in which the driver was cited for speeding or in which driver-related factors coded indicated speed as a factor (e.g., driving too fast for conditions, racing). 2.1. Current Crash Rates Fatal crash rates per 100 million miles traveled were calculated using 2001–02 FARS data, and police reported crash rates per 1 million miles traveled were calculated using 2001–02 NASS/GES data. Fatal and police-reported crashes in 2005 per population were calculated using population estimates from the U.S. Census Bureau. All rates were based on passenger vehicle drivers' fatal and police-reported crash involvement. Rates were examined by passenger presence and by time of day — nighttime (9 p.m. to 5:59 a.m.) versus daytime (6 a.m. to 8:59 p.m.). 2.2. Crash Rate Changes Changes in crash rates were examined by comparing rates for 2005 with those for 1996, the period during which the majority of U.S. states adopted graduated licensing laws for the youngest drivers. Because of limitations in the driver licensing data and a lack of recent mileage data, it was not possible to examine all of the measures of interest to determine whether driver crash risk had changed during this period. Thus the analyses examined changes in per population crashes as well as changes in the underlying crash characteristics such as presence of alcohol, time of day, and passenger presence. 3. Results In 2005, a total of 3,889 passenger vehicle occupants ages 16–19 were killed on U.S. roads, and an estimated
S.A. Ferguson et al. / Journal of Safety Research 38 (2007) 137–145 Table 1 Estimated average annual miles traveled by driver age, 2001–02 NHTS Age
Miles
16 17 18 19 20–24 25–29 30–34 35–39 40–44 45–49 50–54 55–59 60–64 65–69 70–74 75–79 80–84 ≥85
7,179 9,843 12,704 15,570 15,860 17,277 16,539 17,462 17,158 16,677 16,514 14,300 14,357 12,641 10,375 8,786 7,186 5,806
1.89 million were involved in police-reported crashes. This is 8% fewer deaths (4212) and 20% fewer police reported crashes (2.37 million) than occurred in 1996 for this age group. 3.1. Crashes per Mile Traveled during 2001–02 Table 1 shows the estimated average number of miles driven per year by driver age during 2001–02. Teenage drivers, especially 16 year-olds, drove fewer miles per year than all but the oldest drivers (85 and older). Sixteen year-olds drove an average of about 7,000 miles per year, compared with almost 10,000 miles for 17 year-olds. Drivers ages 25–54 drove an average of about 16,500 to 17,500 miles per year, more than twice as many miles as 16 year-olds. Crashes per mile traveled represent crash risk for a quantifiable amount of exposure. Fig. 1 shows fatal crashes
139
per 100 million miles traveled by driver age and gender during 2001–02, corresponding with the period during which the mileage data were collected. Fatal crash rates were highest for teenage drivers (ages 16–19) and drivers 80 and older, and lowest for drivers ages 30–74 (rates among the oldest drivers were based on relatively few respondents, so estimates may be less reliable). However, factors contributing to the high fatal crash rates differ between the youngest and oldest drivers. The high fatal crash rates among teenage drivers are due primarily to their youthful age and inexperience. Older drivers' high fatal crash rates result primarily from their physical fragility. That is, older drivers are more likely to be injured in crashes and are more likely subsequently to die from their injuries (Li et al., 2003). Among teenage drivers, 16 year-olds had the highest fatal crash rate, about 6 times higher than the rate for the lowest risk drivers. Among 16 year-olds, males had the higher fatal crash rate (11 fatal crashes per 100 million miles traveled versus 7 per 100 million miles for 16 year-old females, and 2 per 100 million miles for drivers ages 30–59). Male drivers had higher fatal crash rates than females until age 65, although the gender differences were most pronounced during the teenage years. Rates of police-reported crashes per mile traveled during 2001–02 varied similarly with age (Fig. 2). Estimated crash rates for 16-year-old drivers again were higher than for all other age groups–26 crashes per million miles traveled, versus 14 for drivers ages 18–19, and 4 for drivers ages 30–59 (Fig. 2). Unlike the gender differences observed for fatal crashes, male and female drivers in all age groups had similar police-reported crash rates. 3.2. Crashes per Mile Traveled during 2001–02 by Time of Day Fig. 3 shows mileage-based fatal crash rates during 2001– 02 by driver age and time of day. For all age groups, fatal crashes per mile traveled were higher at night (9 p.m. to 5:59 a.m.) than during the day (6 a.m. to 8:59 p.m.), but the largest differences were among teenage drivers. Daytime fatal crash
Fig. 1. Fatal Passenger Vehicle Crashes per 100 Million Miles Traveled by Driver Age and Gender, 2001–02 FARS, NHTS.
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Fig. 2. Police-Reported Passenger Vehicle Crashes per Million Miles Traveled by Driver Age and Gender, 2001–02 NASS/GES, NHTS.
rates were highest for 16 year-olds, but 17 year-olds had the highest nighttime rates, declining thereafter. Nighttime and daytime police-reported crash rates followed the same general pattern by age, with 16-year-old drivers having the highest daytime rates and 17 year-old drivers having the highest nighttime rates (Fig. 4). However, the differences between daytime and nighttime police-reported crash rates were much smaller during the teenage years than the differences for fatal crash rates, and the differences essentially disappeared after age 25. 3.3. Crashes per Population in 2005 A smaller percentage of the teenage population is licensed to drive, and teenagers tend to drive fewer annual miles than all but the oldest drivers. Among teenage drivers, 16 year-olds are less likely to obtain a license than other teenagers and they drive fewer miles. Their crash rates per population reflect these facts and are not as elevated, relative to other ages, as rates per mile traveled (Table 2). In fact, drivers ages 20–24 had slightly
higher per population fatal crash rates than drivers ages 16–19 (34 vs. 32 crashes per 100,000 population). Further, 16 yearolds had the lowest fatal crash rate among 16–19 year-old drivers; the crash rate for 16 year-olds was about half that for 18 and 19 year-olds (19 vs. 40 crashes per 100,000 population). When police-reported crashes were examined, 18 year-old drivers had the highest crash rates, substantially higher than 16 year-olds (92 vs. 56 crashes per 1000 population) (Table 2). Crashes per population also differed by gender. Female drivers had lower fatal crash rates than male drivers throughout the teenage years and into adulthood. For police-reported crashes, female drivers had slightly higher per population crash rates at age 16, but by age 17 crash rates among males eclipsed those of females and remained higher throughout the age span. 3.4. Fatal Crashes Involving Alcohol in 2005 All U.S. states have zero tolerance laws making it illegal for people younger than 21 to drive with any measurable
Fig. 3. Fatal Passenger Vehicle Crashes per 100 Million Miles Traveled by Driver Age and Time of Day, 2001–02 FARS, NHTS.
S.A. Ferguson et al. / Journal of Safety Research 38 (2007) 137–145
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Fig. 4. Police-Reported Passenger Vehicle Crashes per 1 Million Miles Traveled by Driver Age and Time of Day, 2001–02 NASS/GES, NHTS.
amount of alcohol in their bodies (IIHS, 2007). Fig. 5 shows the percentage of fatally-injured passenger vehicle drivers with positive BACs by driver age and gender during 2005. Data on driver BACs in nonfatal crashes are not provided because of their limited availability in police crash reports. The percentage of fatally injured drivers with positive BACs was lower for 16 year-olds than for other teenage drivers; this was the case for both males and females. The percentage increased through the teenage years and ages 20–29 and declined thereafter, with the lowest rates among the oldest drivers. Fatally injured female drivers in all age groups had consistently lower percentages of positive BACs compared with male drivers, and even the highest percentage for females was considerably lower than that for males of that age group. Similar patterns were observed when examining percentages of drivers with BACs at or above 0.08% (data not shown). 3.5. Teenage Passenger Deaths in Passenger Vehicles in 2005 A large proportion of 16–19 year-olds killed in passenger vehicles in 2005 were riding as passengers. Passengers accounted for 40% of all passenger and driver deaths in 2005 (Table 3). The largest proportion of passenger deaths (51%) occurred among 16 year-olds. The death rate per population for 16–19-year-old passengers was higher than for passengers of other age groups combined (9 vs. 3 per 100,000 population) (table not shown). Most of the teenage passenger deaths occurred when other teenagers were driving. This was particularly evident for 16 year-old passengers, 70% of whom died when another teenager was driving (table not shown). Examination of fatal crash characteristics provides insight into the factors involved in high death rates among teenage drivers (Table 4). Teenage drivers in fatal crashes, especially 16 year-olds, were more likely than drivers 20 and older to have committed a driver error, to have been speeding, and to have been transporting three or more occupants in the
vehicle. However, 16 year-old drivers in fatal crashes were less likely to have positive BACs compared with drivers of other ages. Table 5 shows the crash characteristics of 16–17-year-old drivers in fatal crashes as a function of passenger presence in the vehicle. As the number of teenage passengers increased, fatal crashes among 16- and 17-year-old drivers were more likely to have involved a single vehicle, speeding, and driver error. With three or more teenage passengers, 85% of the crashes involved driver error, almost half involved speeding, and almost 70% involved a single vehicle. 3.6. Changes in Crash Rates between 1996 and 2005 3.6.1. Crashes per Population Between 1996 and 2005, the 16 year-old driver fatal crash rate per 100,000 people declined from 33 to 19 per 100,000 population, a 42% decrease (Table 6). By comparison, among 17 year-olds, per population rates decreased 23%. Fatal crash rates declined 15% for 18-year-old drivers and 7% for 19-year-old drivers. Among drivers ages 30–59, rates declined 15%. Thus, 16 year-olds experienced the greatest Table 2 Fatal and police-reported crash involvements per population by driver age and gender, 2005 FARS and 2005 NASS/GES Age
16 17 18 19 16–19 20–24 25–29 30–59 60–69 70+
Fatal crashes per 100,000 population
Police-reported crashes per 1000 population
Males
Females
Total
Males
Females
Total
23 38 55 54 43 49 35 24 22 26
15 21 24 24 21 19 15 11 9 9
19 30 40 40 32 34 25 17 15 16
55 85 106 95 85 77 66 46 32 27
58 76 78 76 72 65 49 35 20 15
56 80 92 86 79 71 58 40 26 20
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Fig. 5. Percentage of Fatally-Injured Passenger Vehicle Drivers with Positive BACs by Driver Age and Gender, 2005 FARS.
reduction in fatal crashes per population, followed by 17 and then 18 year-olds. Reductions for 19 year-olds were somewhat lower than for drivers ages 30–59. During the same time period, police-reported crash involvements per 1000 population also decreased the most (41%) among 16 year-old drivers (Table 6). This compares with reductions of 26% for 17 year-olds, 19% for 18 yearolds, 12% for 19 year olds, and 26% for drivers ages 30–59. Again 16 year-old drivers experienced the largest percentage reduction in police-reported crashes per population compared with drivers of other ages. When changes in fatal crash rates per population were examined by driver age and gender, reductions generally were greater for males than for females. Among 16 year olds, fatal crash rates per population decreased 44% for males versus 39% for females. Similar gender differences were found among 17 and 18-year-old drivers (25 vs. 20% and 17 vs. 12%, respectively). Nineteen year-old male drivers experienced a
Table 3 Occupant deaths in passenger vehicles by driver age, 2005 FARS Age
Driver deaths Passenger deaths Total
16 356 17 519 18 736 19 724 Total 2,335
365 386 415 380 1,546
3.6.2. Fatal Crashes Involving Teenage Passengers Many U.S. GDL laws restrict the number of teenage passengers the youngest drivers may carry when first licensed. The effects of these restrictions can be seen by examining the fatal crash involvements of 16-year-old drivers as a function of passenger presence (see Table 7). Between 1996 and 2005, Table 5 Characteristics of fatal crashes among 16–17 year-olds when driving alone or when carrying teenage passengers (Percent), 2005 FARS
Driver error Speeding Single vehicle Drivers killed with positive BACs
Driver alone
Driver and 1 teenage passenger
Driver and 2 teenage passengers
Driver and 3+ teenage passengers
71 30 41 12
75 34 45 15
78 42 57 12
85 46 69 16
Percent passenger deaths
722 909 1,154 1,104 3,889
Table 6 Fatal crashes per 100,000 population by driver age, 1996 vs. 2005 FARS
51 42 36 34 40
Table 4 Characteristics of fatal crashes by driver age (Percent), 2005 FARS
Age
1996
2005
Percent reduction
16 17 18 19 30–59
33 39 47 43 20
19 30 40 40 17
42 23 15 7 15
Police-Reported Crashes per 1,000 Population by Driver Age, 1996 vs. 2005 NASS/GES
Driver age
Driver error Speeding Single vehicle 3+ occupants Driver killed with positive BACs
10% reduction versus a 1% increase among female drivers. Similar patterns occurred when examining police-reported crashes per population by driver age and gender.
16
17
18
19
20–25
26–49
Age
1996
2005
Percent reduction
74 34 49 29 15
73 32 47 24 23
71 33 44 23 30
68 33 46 24 32
64 30 45 19 53
51 19 38 17 48
16 17 18 19 30–59
95 108 113 98 54
56 80 92 86 40
41 26 19 12 26
S.A. Ferguson et al. / Journal of Safety Research 38 (2007) 137–145 Table 7 Fatal crashes of 16-year-old drivers by passenger presence, 1996 vs. 2005 FARS Crashes
No passengers Teenage passengers only One Two Three or more Total Other passenger combinations Total
Percent
1996
2005
reduction
426
324
24
309 175 144 628 215 1,269
206 93 72 371 110 805
33 47 50 41 49 37
fatal crashes involving 16 year-old drivers decreased 37% overall. 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%. By comparison, crashes involving 16 year-olds driving alone decreased 24%. Furthermore, the percent of fatal crashes involving 16 year-olds carrying 3 or more passengers was reduced by half. Because of inconsistencies in NASS/GES for reporting passenger data, similar analyses were not conducted for police-reported crashes. 3.6.3. Fatal Crashes Involving Alcohol Table 8 illustrates the percentage change between 1996 and 2005 in the percent of fatally injured drivers with positive BACs, by driver age. The largest reductions occurred among the youngest (age 16) and oldest (60 and older) drivers. Reductions ranged from 16% for 16 year-old drivers to 5–9% for 17–19 year-old drivers, and 14% for drivers 60 and older. There was almost no change among drivers ages 20–29; the groups with the highest percentage of positive BACs.
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Table 9 Daytime and nighttime fatal crashes per 100,000 population by driver age, 1996 vs. 2005 FARS Age
1996
2005
Percent reduction
Daytime (6 a.m. to 16 17 18 19 30–59
8:59 p.m.) 22 25 28 24 14
14 19 24 23 12
40 24 14 3 12
6 10 16 17 5
48 24 17 12 11
Nighttime (9 p.m. to 5:59 a.m.) 16 11 17 14 18 19 19 19 30–59 6
30–59 year-old drivers were not different for nighttime and daytime crashes (24% at night and during the day for 17 year-olds; 12 during the day vs. 11% at night for 30–59 year-olds). During the same period, the percentage reductions in police-reported crashes per population for 16- and 17 year-old drivers were larger at night than during the day (47% vs. 39% respectively among 16 year-olds; 29 vs. 24% among 17 yearolds) (see Table 10). Drivers ages 30–59 also experienced greater reductions in their nighttime police-reported crash rates per population (30% at night vs. 24% in the day). Thus, although the pattern of reductions in per population fatal and nonfatal crash rates by time of day varies as a function of driver age, the reductions among 16 year-olds were consistently higher at night than during the day. 4. Conclusions
3.6.4. Daytime and Nighttime Fatal Crashes Between 1996 and 2005, percentage reductions in the number of fatal crashes per population among 16-year-olddrivers were larger for crashes occurring at night than during the day (Table 9). Nighttime and daytime fatal crash rates decreased 48% and 40%, respectively, among this age group. Reductions in per population fatal crash rates among 17- and Table 8 Percent of fatally-injured passenger vehicle drivers with positive BACs by driver age, 1996 vs. 2005 FARS Age
16 17 18 19 20–24 25–29 30–59 60–69 70+
Percent 1996
2005
18 25 31 35 53 56 46 21 9
15 23 30 32 52 55 42 18 8
Percent reduction 16 7 5 9 2 2 8 14 14
The number of teenagers killed in motor vehicle crashes in 2005 in the United States was the lowest since 1992, despite the largest population of teenagers since 1977 (IIHS, 2006a). Similar progress has not been realized among drivers Table 10 Daytime and nighttime police-reported crashes per 1,000 population by driver age, 1996 vs. 2005 NASS/GES Age
1996
2005
Percent reduction
Daytime (6 a.m. to 16 17 18 19 30–59
8:59 p.m.) 80 91 92 80 47
49 69 75 68 36
39 24 18 14 24
7 11 17 17 5
47 29 16 4 30
Nighttime (9 p.m. to 5:59 a.m.) 16 14 17 16 18 20 19 18 30–59 7
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of other ages. During the past decade there have been dramatic reductions in per population rates for both fatal and police-reported crashes among 16 year-olds, and the reductions are of about the same magnitude. Reductions also have been recorded for 17-year-old drivers, but these reductions are not as dramatic. Graduated licensing is designed to reduce high-risk driving situations among the youngest drivers. Most often these are 16 year-olds, but 17 year-olds often are affected by the requirements as well. Although the present study was not intended to evaluate the effects of graduated licensing per se, results suggest that graduated licensing laws have been successful in reducing fatalities among the youngest drivers. This is consistent with the findings of Chen, Baker, and Li (2006). Compared with states that had no GDL provisions, the authors found reductions of 16% to 21% in the per population fatal crash rate among 16 year-old drivers in states with graduated licensing provisions that included a 3 month or longer mandatory leaners' permit period and a nighttime driving restriction, plus either 30 or more hours of supervised driving or a passenger restriction. There is some concern that delaying full-privilege licensure until age 17 or 18 could result in higher crash risks among 18 year-old drivers because of their reduced exposure in the beginning years of driving. However, there is little evidence from the present study that reduced fatal crash rates among younger drivers have been at the cost of higher fatal crash rates among older teenagers (see also Williams, 2007). It would be gratifying to be able to point definitively to the factors responsible for the declines in fatal crashes per population. Is it because teenagers were licensed for less time during the year when they turned 16? That is, were 16 yearolds obtaining licenses later, or were fewer of them licensed at all thus reducing driving exposure? Is it because the nature of driving exposure changed with added restrictions on when and with whom beginning drivers can drive? Or were beginners driving more safely as a result of the longer learner periods and potentially greater experience under a wider range of conditions? Some or all of these factors could have contributed to the decline, but the present study could not identify which of these factors were important and by how much. Williams (2007) examined the evidence on the effectiveness of specific graduated licensing components to try to disentangle some of these factors. A closer examination of fatal crashes, for which comprehensive data are available, indicates where progress has been made. For example, fatal crashes in 2005 involving 16 yearolds were less likely than such crashes in 1996 to involve multiple teenage passengers in the vehicle. Among 16 yearolds, crashes such as these have been reduced by more than half (see also Williams, Ferguson, & McCartt, 2006). Some concern has been raised that progress in this area may be made at the cost of additional crashes that could occur if more teenagers drive alone, but reductions also were found in the numbers of fatal crashes in which the 16 year-old drivers were
alone. Other studies designed to assess graduated licensing effectiveness have found that passenger restrictions have been beneficial in reducing crashes (Chen et al., 2006; Cooper, Gillen, & Atkins, 2004; Highway Safety Research Center Directions, 2006; Masten & Hagge, 2003; Morrisey, Grabowski, Dee, & Campbell, 2006; Rice, Peek-Asa, & Kraus, 2004; Williams et al., 2006; Zwicker, Williams, Chaudhary, & Farmer, 2006). In addition, the percentage of fatal crashes at night as well as those involving alcohol has declined more among 16 year-old drivers than among older teenagers. In summary, we have seen dramatic reductions in the per population crash rates, both fatal and nonfatal, of 16 yearold drivers. These gains do not appear to be at the expense of older teenage drivers whose rates also have declined but by smaller amounts. Fatal crashes among 16 year-olds are at a historic low. Acknowledgments The authors wish to thank Allan Williams and Adrian Lund for their helpful comments. This work was supported by the Insurance Institute for Highway Safety. References Chen, L., Baker, S. P., Braver, E. R., & Li, G. (2000). Carrying passengers as a risk factor for crashes fatal to 16–17-year-old driver. Journal of the American Medical Association, 283, 1578−1617. Chen, L., Baker, S. P., & Li, G. (2006). Graduated driver licensing programs and fatal crashes of 16-year-old drivers. Pediatrics, 118, 56−62. Cooper, D., Gillen, D., & Atkins, F. (2004). Impacts of California's graduated licensing law of 1998. Berkeley, CA: University of California Institute of Transportation Economics. Doherty, S. T., Andrey, J. C., & MacGregor, C. (1998). The situational risks of young drivers: The influence of passengers, time of day, and day of the week on accident rates. Accident Analysis and Prevention, 30, 45−52. Highway Safety Research Center Directions. (2006). Evaluating the effects of NC's teen driver cell phone restriction. Chapel Hill, NC: University of North Carolina. Insurance Institute for Highway Safety [IIHS]. (2006). Fatality Facts 2005: Teenagers.: Insurance Institute for Highway Safety [IIHS] Arlington, VA, Available at http://www.iihs.org (accessed 7 December 2006). Insurance Institute for Highway Safety [IIHS]. (2006). Laws and regulations, regulatory comments.: Insurance Institute for Highway Safety [IIHS] Arlington, VA, Available at http://www.iihs.org (accessed 7 December 2006). Insurance Institute for Highway Safety [IIHS]. (2007). Q and A teenagers: Underage drinking.: Insurance Institute for Highway Safety [IIHS] Available at http://www.iihs.org (accessed 24 January 2007). Li, G., Braver, E. R., & Chen, L. (2003). Fragility versus excessive crash involvement as determinants of high death rates per vehicle-mile of travel among older drivers. Accident Analysis and Prevention, 35, 227−235. Lyman, S., Ferguson, S. A., Braver, E. R., & Williams, A. F. (2002). Older driver involvements in police reported crashes and fatal crashes: trends and projections. Injury Prevention, 8, 116−120. Masten, S. V., & Hagge, R. A. (2003). Evaluation of California's graduated driver licensing program. Report no. 205. Sacramento, CA: California Department of Motor Vehicles. Mayhew, D. R., Simpson, H. M., & Pak, A. (2003). Changes in collision rates among novice drivers during the first months of driving. Accident Analysis and Prevention, 35, 638−691.
S.A. Ferguson et al. / Journal of Safety Research 38 (2007) 137–145 Morrisey, M. A., Grabowski, D. C., Dee, T. S., & Campbell, C. (2006). The strength of graduated drivers license programs and fatalities among teen drivers and passengers. Accident Analysis and Prevention, 38(1), 135−141. Preusser, D. F., Ferguson, S. A., & Williams, A. F. (1998). The effect of teenage passengers on fatal crash risk of teenage drivers. Accident Analysis and Prevention, 30, 217−222. Rice, T. M., Peek-Asa, C., & Kraus, J. F. (2004). Effects of California graduated driver licensing program. Journal of Safety Research, 35, 63−69. Shope, J. T. (2007). Graduated Driver Licensing: Review of Evaluation Results since 2002. Journal of Safety Research, 37(2). Ulmer, R. G., Williams, A. F., & Preusser, D. F. (1997). Crash involvements of 16-year-old drivers. Journal of Safety Research, 28, 97−103. Williams, A. F. (2003). Teenage drivers: patterns of risk. Journal of Safety Research, 34, 5−15. Williams, A. F. (2007). Contribution of the Components of Graduated Licensing to Crash Reductions. Journal of Safety Research, 37(2). Williams, A. F., Ferguson, S. A., & McCartt, A. (2006). Passenger effects on teenage driving and opportunities for reducing the risks of such travel. Arlington, VA: Insurance Institute for Highway Safety. Williams, A. F., Ferguson, S. A., & Wells, J. K. (2005). Sixteen-year-old drivers in fatal crashes, United States, 2003. Traffic Injury Prevention, 6, 202−206. Zwicker, T. J., Williams, A. F., Chaudhary, N. K., & Farmer, C. M. (2006). Evaluation of California's graduated licensing system. Arlington, VA: Insurance Institute for Highway Safety.
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Susan A. Ferguson, Ph.D. is President, Ferguson International, a highway safety research consulting company. Dr. Ferguson received a B.A. in psychology in 1980 and a Ph.D. in experimental psychology from the George Washington University in 1991. Formerly senior vice president for research at the Insurance Institute for Highway Safety Dr. Ferguson directed research activities in a wide range of highway safety areas determining priorities and overseeing their execution. During her 15 years at the Institute (1991–2006). Susan conducted research in many different highway safety areas with emphasis on young and older drivers, vehicle safety issues, alcohol and driving, and child occupant protection, and has published more than 100 scientific papers. She has been invited to present on highway safety research to diverse audiences both in the U.S. and around the world and has frequently been featured on national television, radio, and in print. Dr. Ferguson serves on many committees and advisory boards both within the U.S. and internationally, and chairs the Blue Ribbon Panel on Advanced Airbags and the Blue Ribbon Panel for the Development of Advanced Alcohol Detection Technology. She serves on the Executive Board of the International Council on Alcohol, Drugs and Traffic Safety, and the Transportation Research Board Committee on Alcohol, Other Drugs and Transportation Committee.
www.elsevier.com/locate/jsr
www.nsc.org
Progress in teenage crash risk during the last decade Susan A. Ferguson a,⁎, Eric R. Teoh b , Anne T. McCartt b a
b
Ferguson International LLC, 1328 Lancia Drive, McLean, VA 22102, USA Insurance Institute for Highway Safety, 1005 North Glebe Road, Arlington, VA 22201, USA Available online 28 March 2007
Abstract Objective: The purpose of the present study was to examine the most recent data on teenagers' fatal and nonfatal crashes in the United States to determine current crash rates as well as changes in crash rates during the past decade Methods: Data for calendar years 1996 and 2005 were extracted for fatal crashes from the Fatality Analysis Reporting System and for police-reported crashes from the National Automotive Sampling System/General Estimates System. To calculate crash rates, population data were obtained from the Census Bureau, and mileage data were obtained from the 2001 National Household Travel Survey Results: During 2001–02, the latest year for which mileage data are available, 16 year-old drivers had higher fatal and nonfatal crash rates per mile traveled than all but the very oldest drivers. However, fewer 16 year-olds typically are licensed to drive and they drive fewer miles per year than all but the oldest drivers. Thus, their fatal and nonfatal crash rates per population in 2005 were lower than among other teenagers and among drivers 20–29. During the past decade the most progress has been made in reducing crashes among the youngest drivers. Between 1996 and 2005 both fatal and police-reported crashes per population declined about 40% for 16 year-old drivers, compared with about 25% for 17 year-old drivers and 15–19% for 18 year-old drivers. The greatest reductions for 16 year-olds occurred in nighttime crashes, alcohol-related fatal crashes, and fatal crashes involving multiple teenage passengers. Conclusions: Substantial progress has been made in reducing fatal and nonfatal crashes per population among 16 year-old drivers. Although this study was not designed to examine the role of graduated licensing, the results are consistent with the increased presence of such laws, many of which restrict nighttime driving and driving with teenage passengers. Impact on Industry: Restrictions on nighttime driving and driving with teenage passengers should be made a part of all states’ graduated licensing systems. Historically, 16 year-olds have had the highest crash risk per licensed driver and per mile traveled. Given the dramatic reductions in per population crash rates among 16 year-olds, it is possible that their per mile and per licensed driver rates also have declined and may no longer be as elevated relative to other ages. However, shortcomings in the licensed driver data and a lack of recent mileage data hamper our ability to examine these issues. If we are to continue to provide a yardstick against which we can measure progress among the youngest drivers, immediate steps need to be taken to restore the availability of reliable exposure data. © 2007 National Safety Council and Elsevier Ltd. All rights reserved.
1. Introduction Teenage drivers, especially 16 year-olds, have long been considered to pose the greatest risk to themselves and other road users, and for good reason. Historically, their fatal crashes per mile traveled and per licensed driver have been higher than for all but the very oldest drivers (Li, Braver, & Chen, 2003; Lyman, Ferguson, Braver, & Williams, 2002). Beginning drivers of all ages have higher crash rates than drivers with more experience, but the youngest drivers are known to take addi-
⁎ Corresponding author. Tel.: +1 703 847 5317. E-mail address: [email protected] (S.A. Ferguson).
tional risks because of youthful exuberance and immaturity (Mayhew, Simpson, & Pak, 2003). Teenage crash risk is particularly elevated when driving at night and when carrying teenage passengers (Chen, Baker, Braver, & Li, 2000; Doherty, Andrey, & MacGregor, 1998; Preusser, Ferguson, & Williams, 1998; Ulmer, Williams, & Preusser, 1997; Williams, 2003; Williams, Ferguson, & Wells, 2005). Legislators in many states have tried to address these concerns through the adoption of graduated driver licensing (GDL) laws. Starting with Florida in 1996, U.S. states have modified their laws requiring beginning drivers to complete a series of stages before obtaining full-privilege licenses. The majority of states now have some form of graduated licensing. Typically after a learner's permit period of at least 6 months,
0022-4375/$ - see front matter © 2007 National Safety Council and Elsevier Ltd. All rights reserved. doi:10.1016/j.jsr.2007.02.001
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teenagers are given restricted licenses that often prohibit driving unsupervised at night or carrying one or more teenage passengers (Insurance Institute for Highway Safety [IIHS], 2006a). Once these stages have been negotiated successfully, teenagers can obtain unrestricted licenses. Research examining the effectiveness of graduated licensing at the state level, as well as comprehensive evaluations of national fatal crash data, have demonstrated consistently that GDL programs are effective in reducing crashes among the youngest drivers (see Shope, 2007). Williams (2003) examined crash data from 2000 and crash rates per mile traveled from 1995 to compare the crash risk of teenage drivers with that of drivers of other ages. He concluded, “On most measures, crash rates during the teenage years are higher than for any other age, for both males and females.” To the extent possible the present paper will answer the question of whether this conclusion still is true. Recent research suggests that we have seen significant progress in the United States toward reducing fatal crashes per population among 16 year-old drivers. Williams et al. (2005) found that crashes per population declined more for 16 year-old drivers than for drivers of other ages. Between 1993 and 2003, fatal crashes per population declined 26% for 16 year-old drivers, 11% for 17 year-old drivers, 6% for 18–19 year olds, and 7% for drivers ages 20–49. There were few differences over time in the percentages of fatal crashes that occurred at night, or involved single vehicles, driver error, or speeding. However, the proportion of fatal crashes in which 16-year-old drivers were transporting only teenage passengers decreased from 53% in 1993 to 44% in 2003. The present paper provides updated information on teenage driver crash rates, including rates for fatal and nonfatal crashes. Ideally, a comprehensive evaluation of crash rates and crash rate trends would include calculations per population, per licensed driver, and per mile traveled. However, examination of annual state-by-state counts of licensed drivers published by the Federal Highway Administration revealed that teenage drivers have been undercounted in some states for the past several years (Insurance Institute for Highway Safety, 2006b). Researchers found large year-to-year differences in licensed driver counts in a number of states, and these differences could not be explained by fluctuations in population or changes in state licensing laws. The IIHS concluded that these current and historical data do not provide reliable measures of the number of licensed drivers, especially the youngest ones. 2. Methods Teenage drivers' crash risk, for both fatal and nonfatal crashes, was examined using the latest available data from a variety of sources. In-depth mileage data were obtained from the National Household Travel Survey (NHTS), formerly the Nationwide Personal Transportation Survey. NHTS collects mileage data from a sample of drivers of all ages, including data on travel at different times of the day. Samples can be weighted to provide national estimates. Surveys typically are
conducted about every 5 years, but the latest survey was conducted during April 2001–May 2002. Data on fatal crashes were obtained from the Fatality Analysis Reporting System (FARS). FARS is a virtual census of fatal motor vehicle crashes that occur on public roads in the United States in which vehicle occupants or other road users die within 30 days of a crash. Data on police-reported crashes were obtained from the National Automotive Sampling System/General Estimates System (NASS/GES). NASS/ GES contains a representative sample of U.S. police-reported crashes that can be weighted to provide national estimates. Crashes were examined as a function of driver gender and age. Fatal crash characteristics examined included driver error, speeding, crash type, and drivers' blood alcohol concentrations (BAC). The definition of driver error was based on driver-related factors coded in FARS and was intended to capture the physical movements of the vehicle that were clearly indicative of driver mistakes (e.g., improper lane change, passing on the wrong side, overcorrecting). Codes for driver physical/mental conditions such as inattention, drowsiness, or alcohol impairment were excluded. Speeding was defined to include cases in which the driver was cited for speeding or in which driver-related factors coded indicated speed as a factor (e.g., driving too fast for conditions, racing). 2.1. Current Crash Rates Fatal crash rates per 100 million miles traveled were calculated using 2001–02 FARS data, and police reported crash rates per 1 million miles traveled were calculated using 2001–02 NASS/GES data. Fatal and police-reported crashes in 2005 per population were calculated using population estimates from the U.S. Census Bureau. All rates were based on passenger vehicle drivers' fatal and police-reported crash involvement. Rates were examined by passenger presence and by time of day — nighttime (9 p.m. to 5:59 a.m.) versus daytime (6 a.m. to 8:59 p.m.). 2.2. Crash Rate Changes Changes in crash rates were examined by comparing rates for 2005 with those for 1996, the period during which the majority of U.S. states adopted graduated licensing laws for the youngest drivers. Because of limitations in the driver licensing data and a lack of recent mileage data, it was not possible to examine all of the measures of interest to determine whether driver crash risk had changed during this period. Thus the analyses examined changes in per population crashes as well as changes in the underlying crash characteristics such as presence of alcohol, time of day, and passenger presence. 3. Results In 2005, a total of 3,889 passenger vehicle occupants ages 16–19 were killed on U.S. roads, and an estimated
S.A. Ferguson et al. / Journal of Safety Research 38 (2007) 137–145 Table 1 Estimated average annual miles traveled by driver age, 2001–02 NHTS Age
Miles
16 17 18 19 20–24 25–29 30–34 35–39 40–44 45–49 50–54 55–59 60–64 65–69 70–74 75–79 80–84 ≥85
7,179 9,843 12,704 15,570 15,860 17,277 16,539 17,462 17,158 16,677 16,514 14,300 14,357 12,641 10,375 8,786 7,186 5,806
1.89 million were involved in police-reported crashes. This is 8% fewer deaths (4212) and 20% fewer police reported crashes (2.37 million) than occurred in 1996 for this age group. 3.1. Crashes per Mile Traveled during 2001–02 Table 1 shows the estimated average number of miles driven per year by driver age during 2001–02. Teenage drivers, especially 16 year-olds, drove fewer miles per year than all but the oldest drivers (85 and older). Sixteen year-olds drove an average of about 7,000 miles per year, compared with almost 10,000 miles for 17 year-olds. Drivers ages 25–54 drove an average of about 16,500 to 17,500 miles per year, more than twice as many miles as 16 year-olds. Crashes per mile traveled represent crash risk for a quantifiable amount of exposure. Fig. 1 shows fatal crashes
139
per 100 million miles traveled by driver age and gender during 2001–02, corresponding with the period during which the mileage data were collected. Fatal crash rates were highest for teenage drivers (ages 16–19) and drivers 80 and older, and lowest for drivers ages 30–74 (rates among the oldest drivers were based on relatively few respondents, so estimates may be less reliable). However, factors contributing to the high fatal crash rates differ between the youngest and oldest drivers. The high fatal crash rates among teenage drivers are due primarily to their youthful age and inexperience. Older drivers' high fatal crash rates result primarily from their physical fragility. That is, older drivers are more likely to be injured in crashes and are more likely subsequently to die from their injuries (Li et al., 2003). Among teenage drivers, 16 year-olds had the highest fatal crash rate, about 6 times higher than the rate for the lowest risk drivers. Among 16 year-olds, males had the higher fatal crash rate (11 fatal crashes per 100 million miles traveled versus 7 per 100 million miles for 16 year-old females, and 2 per 100 million miles for drivers ages 30–59). Male drivers had higher fatal crash rates than females until age 65, although the gender differences were most pronounced during the teenage years. Rates of police-reported crashes per mile traveled during 2001–02 varied similarly with age (Fig. 2). Estimated crash rates for 16-year-old drivers again were higher than for all other age groups–26 crashes per million miles traveled, versus 14 for drivers ages 18–19, and 4 for drivers ages 30–59 (Fig. 2). Unlike the gender differences observed for fatal crashes, male and female drivers in all age groups had similar police-reported crash rates. 3.2. Crashes per Mile Traveled during 2001–02 by Time of Day Fig. 3 shows mileage-based fatal crash rates during 2001– 02 by driver age and time of day. For all age groups, fatal crashes per mile traveled were higher at night (9 p.m. to 5:59 a.m.) than during the day (6 a.m. to 8:59 p.m.), but the largest differences were among teenage drivers. Daytime fatal crash
Fig. 1. Fatal Passenger Vehicle Crashes per 100 Million Miles Traveled by Driver Age and Gender, 2001–02 FARS, NHTS.
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Fig. 2. Police-Reported Passenger Vehicle Crashes per Million Miles Traveled by Driver Age and Gender, 2001–02 NASS/GES, NHTS.
rates were highest for 16 year-olds, but 17 year-olds had the highest nighttime rates, declining thereafter. Nighttime and daytime police-reported crash rates followed the same general pattern by age, with 16-year-old drivers having the highest daytime rates and 17 year-old drivers having the highest nighttime rates (Fig. 4). However, the differences between daytime and nighttime police-reported crash rates were much smaller during the teenage years than the differences for fatal crash rates, and the differences essentially disappeared after age 25. 3.3. Crashes per Population in 2005 A smaller percentage of the teenage population is licensed to drive, and teenagers tend to drive fewer annual miles than all but the oldest drivers. Among teenage drivers, 16 year-olds are less likely to obtain a license than other teenagers and they drive fewer miles. Their crash rates per population reflect these facts and are not as elevated, relative to other ages, as rates per mile traveled (Table 2). In fact, drivers ages 20–24 had slightly
higher per population fatal crash rates than drivers ages 16–19 (34 vs. 32 crashes per 100,000 population). Further, 16 yearolds had the lowest fatal crash rate among 16–19 year-old drivers; the crash rate for 16 year-olds was about half that for 18 and 19 year-olds (19 vs. 40 crashes per 100,000 population). When police-reported crashes were examined, 18 year-old drivers had the highest crash rates, substantially higher than 16 year-olds (92 vs. 56 crashes per 1000 population) (Table 2). Crashes per population also differed by gender. Female drivers had lower fatal crash rates than male drivers throughout the teenage years and into adulthood. For police-reported crashes, female drivers had slightly higher per population crash rates at age 16, but by age 17 crash rates among males eclipsed those of females and remained higher throughout the age span. 3.4. Fatal Crashes Involving Alcohol in 2005 All U.S. states have zero tolerance laws making it illegal for people younger than 21 to drive with any measurable
Fig. 3. Fatal Passenger Vehicle Crashes per 100 Million Miles Traveled by Driver Age and Time of Day, 2001–02 FARS, NHTS.
S.A. Ferguson et al. / Journal of Safety Research 38 (2007) 137–145
141
Fig. 4. Police-Reported Passenger Vehicle Crashes per 1 Million Miles Traveled by Driver Age and Time of Day, 2001–02 NASS/GES, NHTS.
amount of alcohol in their bodies (IIHS, 2007). Fig. 5 shows the percentage of fatally-injured passenger vehicle drivers with positive BACs by driver age and gender during 2005. Data on driver BACs in nonfatal crashes are not provided because of their limited availability in police crash reports. The percentage of fatally injured drivers with positive BACs was lower for 16 year-olds than for other teenage drivers; this was the case for both males and females. The percentage increased through the teenage years and ages 20–29 and declined thereafter, with the lowest rates among the oldest drivers. Fatally injured female drivers in all age groups had consistently lower percentages of positive BACs compared with male drivers, and even the highest percentage for females was considerably lower than that for males of that age group. Similar patterns were observed when examining percentages of drivers with BACs at or above 0.08% (data not shown). 3.5. Teenage Passenger Deaths in Passenger Vehicles in 2005 A large proportion of 16–19 year-olds killed in passenger vehicles in 2005 were riding as passengers. Passengers accounted for 40% of all passenger and driver deaths in 2005 (Table 3). The largest proportion of passenger deaths (51%) occurred among 16 year-olds. The death rate per population for 16–19-year-old passengers was higher than for passengers of other age groups combined (9 vs. 3 per 100,000 population) (table not shown). Most of the teenage passenger deaths occurred when other teenagers were driving. This was particularly evident for 16 year-old passengers, 70% of whom died when another teenager was driving (table not shown). Examination of fatal crash characteristics provides insight into the factors involved in high death rates among teenage drivers (Table 4). Teenage drivers in fatal crashes, especially 16 year-olds, were more likely than drivers 20 and older to have committed a driver error, to have been speeding, and to have been transporting three or more occupants in the
vehicle. However, 16 year-old drivers in fatal crashes were less likely to have positive BACs compared with drivers of other ages. Table 5 shows the crash characteristics of 16–17-year-old drivers in fatal crashes as a function of passenger presence in the vehicle. As the number of teenage passengers increased, fatal crashes among 16- and 17-year-old drivers were more likely to have involved a single vehicle, speeding, and driver error. With three or more teenage passengers, 85% of the crashes involved driver error, almost half involved speeding, and almost 70% involved a single vehicle. 3.6. Changes in Crash Rates between 1996 and 2005 3.6.1. Crashes per Population Between 1996 and 2005, the 16 year-old driver fatal crash rate per 100,000 people declined from 33 to 19 per 100,000 population, a 42% decrease (Table 6). By comparison, among 17 year-olds, per population rates decreased 23%. Fatal crash rates declined 15% for 18-year-old drivers and 7% for 19-year-old drivers. Among drivers ages 30–59, rates declined 15%. Thus, 16 year-olds experienced the greatest Table 2 Fatal and police-reported crash involvements per population by driver age and gender, 2005 FARS and 2005 NASS/GES Age
16 17 18 19 16–19 20–24 25–29 30–59 60–69 70+
Fatal crashes per 100,000 population
Police-reported crashes per 1000 population
Males
Females
Total
Males
Females
Total
23 38 55 54 43 49 35 24 22 26
15 21 24 24 21 19 15 11 9 9
19 30 40 40 32 34 25 17 15 16
55 85 106 95 85 77 66 46 32 27
58 76 78 76 72 65 49 35 20 15
56 80 92 86 79 71 58 40 26 20
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Fig. 5. Percentage of Fatally-Injured Passenger Vehicle Drivers with Positive BACs by Driver Age and Gender, 2005 FARS.
reduction in fatal crashes per population, followed by 17 and then 18 year-olds. Reductions for 19 year-olds were somewhat lower than for drivers ages 30–59. During the same time period, police-reported crash involvements per 1000 population also decreased the most (41%) among 16 year-old drivers (Table 6). This compares with reductions of 26% for 17 year-olds, 19% for 18 yearolds, 12% for 19 year olds, and 26% for drivers ages 30–59. Again 16 year-old drivers experienced the largest percentage reduction in police-reported crashes per population compared with drivers of other ages. When changes in fatal crash rates per population were examined by driver age and gender, reductions generally were greater for males than for females. Among 16 year olds, fatal crash rates per population decreased 44% for males versus 39% for females. Similar gender differences were found among 17 and 18-year-old drivers (25 vs. 20% and 17 vs. 12%, respectively). Nineteen year-old male drivers experienced a
Table 3 Occupant deaths in passenger vehicles by driver age, 2005 FARS Age
Driver deaths Passenger deaths Total
16 356 17 519 18 736 19 724 Total 2,335
365 386 415 380 1,546
3.6.2. Fatal Crashes Involving Teenage Passengers Many U.S. GDL laws restrict the number of teenage passengers the youngest drivers may carry when first licensed. The effects of these restrictions can be seen by examining the fatal crash involvements of 16-year-old drivers as a function of passenger presence (see Table 7). Between 1996 and 2005, Table 5 Characteristics of fatal crashes among 16–17 year-olds when driving alone or when carrying teenage passengers (Percent), 2005 FARS
Driver error Speeding Single vehicle Drivers killed with positive BACs
Driver alone
Driver and 1 teenage passenger
Driver and 2 teenage passengers
Driver and 3+ teenage passengers
71 30 41 12
75 34 45 15
78 42 57 12
85 46 69 16
Percent passenger deaths
722 909 1,154 1,104 3,889
Table 6 Fatal crashes per 100,000 population by driver age, 1996 vs. 2005 FARS
51 42 36 34 40
Table 4 Characteristics of fatal crashes by driver age (Percent), 2005 FARS
Age
1996
2005
Percent reduction
16 17 18 19 30–59
33 39 47 43 20
19 30 40 40 17
42 23 15 7 15
Police-Reported Crashes per 1,000 Population by Driver Age, 1996 vs. 2005 NASS/GES
Driver age
Driver error Speeding Single vehicle 3+ occupants Driver killed with positive BACs
10% reduction versus a 1% increase among female drivers. Similar patterns occurred when examining police-reported crashes per population by driver age and gender.
16
17
18
19
20–25
26–49
Age
1996
2005
Percent reduction
74 34 49 29 15
73 32 47 24 23
71 33 44 23 30
68 33 46 24 32
64 30 45 19 53
51 19 38 17 48
16 17 18 19 30–59
95 108 113 98 54
56 80 92 86 40
41 26 19 12 26
S.A. Ferguson et al. / Journal of Safety Research 38 (2007) 137–145 Table 7 Fatal crashes of 16-year-old drivers by passenger presence, 1996 vs. 2005 FARS Crashes
No passengers Teenage passengers only One Two Three or more Total Other passenger combinations Total
Percent
1996
2005
reduction
426
324
24
309 175 144 628 215 1,269
206 93 72 371 110 805
33 47 50 41 49 37
fatal crashes involving 16 year-old drivers decreased 37% overall. 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%. By comparison, crashes involving 16 year-olds driving alone decreased 24%. Furthermore, the percent of fatal crashes involving 16 year-olds carrying 3 or more passengers was reduced by half. Because of inconsistencies in NASS/GES for reporting passenger data, similar analyses were not conducted for police-reported crashes. 3.6.3. Fatal Crashes Involving Alcohol Table 8 illustrates the percentage change between 1996 and 2005 in the percent of fatally injured drivers with positive BACs, by driver age. The largest reductions occurred among the youngest (age 16) and oldest (60 and older) drivers. Reductions ranged from 16% for 16 year-old drivers to 5–9% for 17–19 year-old drivers, and 14% for drivers 60 and older. There was almost no change among drivers ages 20–29; the groups with the highest percentage of positive BACs.
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Table 9 Daytime and nighttime fatal crashes per 100,000 population by driver age, 1996 vs. 2005 FARS Age
1996
2005
Percent reduction
Daytime (6 a.m. to 16 17 18 19 30–59
8:59 p.m.) 22 25 28 24 14
14 19 24 23 12
40 24 14 3 12
6 10 16 17 5
48 24 17 12 11
Nighttime (9 p.m. to 5:59 a.m.) 16 11 17 14 18 19 19 19 30–59 6
30–59 year-old drivers were not different for nighttime and daytime crashes (24% at night and during the day for 17 year-olds; 12 during the day vs. 11% at night for 30–59 year-olds). During the same period, the percentage reductions in police-reported crashes per population for 16- and 17 year-old drivers were larger at night than during the day (47% vs. 39% respectively among 16 year-olds; 29 vs. 24% among 17 yearolds) (see Table 10). Drivers ages 30–59 also experienced greater reductions in their nighttime police-reported crash rates per population (30% at night vs. 24% in the day). Thus, although the pattern of reductions in per population fatal and nonfatal crash rates by time of day varies as a function of driver age, the reductions among 16 year-olds were consistently higher at night than during the day. 4. Conclusions
3.6.4. Daytime and Nighttime Fatal Crashes Between 1996 and 2005, percentage reductions in the number of fatal crashes per population among 16-year-olddrivers were larger for crashes occurring at night than during the day (Table 9). Nighttime and daytime fatal crash rates decreased 48% and 40%, respectively, among this age group. Reductions in per population fatal crash rates among 17- and Table 8 Percent of fatally-injured passenger vehicle drivers with positive BACs by driver age, 1996 vs. 2005 FARS Age
16 17 18 19 20–24 25–29 30–59 60–69 70+
Percent 1996
2005
18 25 31 35 53 56 46 21 9
15 23 30 32 52 55 42 18 8
Percent reduction 16 7 5 9 2 2 8 14 14
The number of teenagers killed in motor vehicle crashes in 2005 in the United States was the lowest since 1992, despite the largest population of teenagers since 1977 (IIHS, 2006a). Similar progress has not been realized among drivers Table 10 Daytime and nighttime police-reported crashes per 1,000 population by driver age, 1996 vs. 2005 NASS/GES Age
1996
2005
Percent reduction
Daytime (6 a.m. to 16 17 18 19 30–59
8:59 p.m.) 80 91 92 80 47
49 69 75 68 36
39 24 18 14 24
7 11 17 17 5
47 29 16 4 30
Nighttime (9 p.m. to 5:59 a.m.) 16 14 17 16 18 20 19 18 30–59 7
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of other ages. During the past decade there have been dramatic reductions in per population rates for both fatal and police-reported crashes among 16 year-olds, and the reductions are of about the same magnitude. Reductions also have been recorded for 17-year-old drivers, but these reductions are not as dramatic. Graduated licensing is designed to reduce high-risk driving situations among the youngest drivers. Most often these are 16 year-olds, but 17 year-olds often are affected by the requirements as well. Although the present study was not intended to evaluate the effects of graduated licensing per se, results suggest that graduated licensing laws have been successful in reducing fatalities among the youngest drivers. This is consistent with the findings of Chen, Baker, and Li (2006). Compared with states that had no GDL provisions, the authors found reductions of 16% to 21% in the per population fatal crash rate among 16 year-old drivers in states with graduated licensing provisions that included a 3 month or longer mandatory leaners' permit period and a nighttime driving restriction, plus either 30 or more hours of supervised driving or a passenger restriction. There is some concern that delaying full-privilege licensure until age 17 or 18 could result in higher crash risks among 18 year-old drivers because of their reduced exposure in the beginning years of driving. However, there is little evidence from the present study that reduced fatal crash rates among younger drivers have been at the cost of higher fatal crash rates among older teenagers (see also Williams, 2007). It would be gratifying to be able to point definitively to the factors responsible for the declines in fatal crashes per population. Is it because teenagers were licensed for less time during the year when they turned 16? That is, were 16 yearolds obtaining licenses later, or were fewer of them licensed at all thus reducing driving exposure? Is it because the nature of driving exposure changed with added restrictions on when and with whom beginning drivers can drive? Or were beginners driving more safely as a result of the longer learner periods and potentially greater experience under a wider range of conditions? Some or all of these factors could have contributed to the decline, but the present study could not identify which of these factors were important and by how much. Williams (2007) examined the evidence on the effectiveness of specific graduated licensing components to try to disentangle some of these factors. A closer examination of fatal crashes, for which comprehensive data are available, indicates where progress has been made. For example, fatal crashes in 2005 involving 16 yearolds were less likely than such crashes in 1996 to involve multiple teenage passengers in the vehicle. Among 16 yearolds, crashes such as these have been reduced by more than half (see also Williams, Ferguson, & McCartt, 2006). Some concern has been raised that progress in this area may be made at the cost of additional crashes that could occur if more teenagers drive alone, but reductions also were found in the numbers of fatal crashes in which the 16 year-old drivers were
alone. Other studies designed to assess graduated licensing effectiveness have found that passenger restrictions have been beneficial in reducing crashes (Chen et al., 2006; Cooper, Gillen, & Atkins, 2004; Highway Safety Research Center Directions, 2006; Masten & Hagge, 2003; Morrisey, Grabowski, Dee, & Campbell, 2006; Rice, Peek-Asa, & Kraus, 2004; Williams et al., 2006; Zwicker, Williams, Chaudhary, & Farmer, 2006). In addition, the percentage of fatal crashes at night as well as those involving alcohol has declined more among 16 year-old drivers than among older teenagers. In summary, we have seen dramatic reductions in the per population crash rates, both fatal and nonfatal, of 16 yearold drivers. These gains do not appear to be at the expense of older teenage drivers whose rates also have declined but by smaller amounts. Fatal crashes among 16 year-olds are at a historic low. Acknowledgments The authors wish to thank Allan Williams and Adrian Lund for their helpful comments. This work was supported by the Insurance Institute for Highway Safety. References Chen, L., Baker, S. P., Braver, E. R., & Li, G. (2000). Carrying passengers as a risk factor for crashes fatal to 16–17-year-old driver. Journal of the American Medical Association, 283, 1578−1617. Chen, L., Baker, S. P., & Li, G. (2006). Graduated driver licensing programs and fatal crashes of 16-year-old drivers. Pediatrics, 118, 56−62. Cooper, D., Gillen, D., & Atkins, F. (2004). Impacts of California's graduated licensing law of 1998. Berkeley, CA: University of California Institute of Transportation Economics. Doherty, S. T., Andrey, J. C., & MacGregor, C. (1998). The situational risks of young drivers: The influence of passengers, time of day, and day of the week on accident rates. Accident Analysis and Prevention, 30, 45−52. Highway Safety Research Center Directions. (2006). Evaluating the effects of NC's teen driver cell phone restriction. Chapel Hill, NC: University of North Carolina. Insurance Institute for Highway Safety [IIHS]. (2006). Fatality Facts 2005: Teenagers.: Insurance Institute for Highway Safety [IIHS] Arlington, VA, Available at http://www.iihs.org (accessed 7 December 2006). Insurance Institute for Highway Safety [IIHS]. (2006). Laws and regulations, regulatory comments.: Insurance Institute for Highway Safety [IIHS] Arlington, VA, Available at http://www.iihs.org (accessed 7 December 2006). Insurance Institute for Highway Safety [IIHS]. (2007). Q and A teenagers: Underage drinking.: Insurance Institute for Highway Safety [IIHS] Available at http://www.iihs.org (accessed 24 January 2007). Li, G., Braver, E. R., & Chen, L. (2003). Fragility versus excessive crash involvement as determinants of high death rates per vehicle-mile of travel among older drivers. Accident Analysis and Prevention, 35, 227−235. Lyman, S., Ferguson, S. A., Braver, E. R., & Williams, A. F. (2002). Older driver involvements in police reported crashes and fatal crashes: trends and projections. Injury Prevention, 8, 116−120. Masten, S. V., & Hagge, R. A. (2003). Evaluation of California's graduated driver licensing program. Report no. 205. Sacramento, CA: California Department of Motor Vehicles. Mayhew, D. R., Simpson, H. M., & Pak, A. (2003). Changes in collision rates among novice drivers during the first months of driving. Accident Analysis and Prevention, 35, 638−691.
S.A. Ferguson et al. / Journal of Safety Research 38 (2007) 137–145 Morrisey, M. A., Grabowski, D. C., Dee, T. S., & Campbell, C. (2006). The strength of graduated drivers license programs and fatalities among teen drivers and passengers. Accident Analysis and Prevention, 38(1), 135−141. Preusser, D. F., Ferguson, S. A., & Williams, A. F. (1998). The effect of teenage passengers on fatal crash risk of teenage drivers. Accident Analysis and Prevention, 30, 217−222. Rice, T. M., Peek-Asa, C., & Kraus, J. F. (2004). Effects of California graduated driver licensing program. Journal of Safety Research, 35, 63−69. Shope, J. T. (2007). Graduated Driver Licensing: Review of Evaluation Results since 2002. Journal of Safety Research, 37(2). Ulmer, R. G., Williams, A. F., & Preusser, D. F. (1997). Crash involvements of 16-year-old drivers. Journal of Safety Research, 28, 97−103. Williams, A. F. (2003). Teenage drivers: patterns of risk. Journal of Safety Research, 34, 5−15. Williams, A. F. (2007). Contribution of the Components of Graduated Licensing to Crash Reductions. Journal of Safety Research, 37(2). Williams, A. F., Ferguson, S. A., & McCartt, A. (2006). Passenger effects on teenage driving and opportunities for reducing the risks of such travel. Arlington, VA: Insurance Institute for Highway Safety. Williams, A. F., Ferguson, S. A., & Wells, J. K. (2005). Sixteen-year-old drivers in fatal crashes, United States, 2003. Traffic Injury Prevention, 6, 202−206. Zwicker, T. J., Williams, A. F., Chaudhary, N. K., & Farmer, C. M. (2006). Evaluation of California's graduated licensing system. Arlington, VA: Insurance Institute for Highway Safety.
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Susan A. Ferguson, Ph.D. is President, Ferguson International, a highway safety research consulting company. Dr. Ferguson received a B.A. in psychology in 1980 and a Ph.D. in experimental psychology from the George Washington University in 1991. Formerly senior vice president for research at the Insurance Institute for Highway Safety Dr. Ferguson directed research activities in a wide range of highway safety areas determining priorities and overseeing their execution. During her 15 years at the Institute (1991–2006). Susan conducted research in many different highway safety areas with emphasis on young and older drivers, vehicle safety issues, alcohol and driving, and child occupant protection, and has published more than 100 scientific papers. She has been invited to present on highway safety research to diverse audiences both in the U.S. and around the world and has frequently been featured on national television, radio, and in print. Dr. Ferguson serves on many committees and advisory boards both within the U.S. and internationally, and chairs the Blue Ribbon Panel on Advanced Airbags and the Blue Ribbon Panel for the Development of Advanced Alcohol Detection Technology. She serves on the Executive Board of the International Council on Alcohol, Drugs and Traffic Safety, and the Transportation Research Board Committee on Alcohol, Other Drugs and Transportation Committee.