Potential of Driver Education to Re Crashes Involving Young23216/FULLTEXT01.pdf · Therefore, it is...

Linköping University Medical Dissertation No. 985

The Potential of Driver Education to Re‐duce Traffic Crashes Involving Young

Drivers

Anders Nyberg

Division of Social Medicine and Public Health Science, Department of Health

and Society, Linköping University, SE‐581 83 Linköping, Sweden

Linköping 2007

The Potential of Driver Education to Reduce Traffic Crashes Involving Young Drivers © Anders Nyberg, 2007 Cover picture by Jonna Nyberg Published papers were reprinted with the permission of the copyright holder. Printed by LiU‐Tryck, Linköping 2007 ISBN: 978‐91‐85715‐69‐5 ISSN: 0345‐0082

CONTENTS ABSTRACT .......................................................................................................................................................... 1

LIST OF PAPERS ................................................................................................................................................ 3

LIST OF FIGURES AND TABLES................................................................................................................... 4

DEFINITIONS ..................................................................................................................................................... 5

1 BACKGROUND ........................................................................................................................................ 7 1.1 TRAFFIC FATALITIES AND INJURIES—A SERIOUS PUBLIC HEALTH PROBLEM...................................... 7 1.2 INVOLVEMENT OF YOUNG DRIVERS IN CRASHES ................................................................................ 8 1.2.1 Fatalities and severe injuries ........................................................................................................... 8 1.2.2 Crash types and circumstances related to injury crashes involving young novice drivers........... 13

1.3 FACTORS ESSENTIAL FOR UNDERSTANDING THE PROBLEMS OF YOUNG DRIVERS............................ 17 1.3.1 Age and experience........................................................................................................................ 17 1.3.2 Gender differences ......................................................................................................................... 19 1.3.3 The impact of experience on development of skills ........................................................................ 19 1.3.4 Individuals’ own estimations of their competence as drivers ........................................................ 22 1.3.5 Individual and social preconditions .............................................................................................. 23

1.4 MEASURES AVAILABLE TO REDUCE THE PROBLEMS OF YOUNG DRIVERS ......................................... 26 1.5 THE POTENTIAL OF DRIVER TRAINING TO REDUCE THE PROBLEMS OF YOUNG DRIVERS ................. 27 1.5.1 The three cornerstones of driver education.................................................................................... 27 1.5.2 Goals of driver education .............................................................................................................. 28 1.5.3 Licensing systems.......................................................................................................................... 31 1.5.4 The Swedish system for obtaining a class B driving license ......................................................... 36

2 AIMS .......................................................................................................................................................... 39

3 MATERIALS AND METHODS ........................................................................................................... 41 3.1 DESCRIPTION OF THE MATERIALS AND METHODS ............................................................................ 41 3.2 GENERAL COMMENTS ABOUT THE MATERIALS AND METHODS ....................................................... 41 3.3 PRACTICING IN RELATION TO THE OUTCOME OF THE DRIVING LICENSE TEST (PAPER I) ................. 44 3.4 PRACTICING FOR AND PERFORMANCE ON DRIVER’S LICENSE TESTS IN RELATION TO GENDER

DIFFERENCES IN CRASH INVOLVEMENT AMONG NOVICE DRIVERS (PAPER II)................................................ 45 3.5 SIXTEEN YEARS AGE LIMIT FOR LEARNER DRIVERS IN SWEDEN—AN EVALUATION OF SAFETY

EFFECTS (PAPER III).......................................................................................................................................... 47 3.6 ACCIDENT INVOLVEMENT AMONG LEARNER DRIVERS—AN ANALYSIS OF THE CONSEQUENCES OF

SUPERVISED PRACTICE (PAPER IV)................................................................................................................... 49 3.7 SAFETY HALLS—AN EVALUATION (PAPER V)................................................................................... 51

4 RESULTS................................................................................................................................................... 55 4.1 PRACTICING IN RELATION TO THE OUTCOME OF THE DRIVING LICENSE TEST (PAPER I) ................. 55 4.2 PRACTICING FOR AND PERFORMANCE ON DRIVER’S LICENSE TESTS IN RELATION TO GENDER

DIFFERENCES IN CRASH INVOLVEMENT AMONG NOVICE DRIVERS (PAPER II)................................................ 58 4.3 SIXTEEN YEARS AGE LIMIT FOR LEARNER DRIVERS IN SWEDEN—AN EVALUATION OF SAFETY

EFFECTS (PAPER III).......................................................................................................................................... 61 4.4 ACCIDENT INVOLVEMENT AMONG LEARNER DRIVERS—AN ANALYSIS OF THE CONSEQUENCES OF

SUPERVISED PRACTICE (PAPER IV)................................................................................................................... 63 4.5 SAFETY HALLS—AN EVALUATION (PAPER V)................................................................................... 64

5 GENERAL DISCUSSION ...................................................................................................................... 67 5.1 VISION ZERO AND THE SWEDISH DRIVER LICENSING SYSTEM.......................................................... 67 5.2 UTILIZATION OF THE REFORM ALLOWING PRACTICING AT THE AGE OF 16 ..................................... 69 5.3 AMOUNT OF DRIVING PRACTICE ....................................................................................................... 70 5.4 STRUCTURE OF THE LEARNING PERIOD ............................................................................................. 72 5.5 THE DRIVING LICENSE TESTS ............................................................................................................. 76 5.6 MANDATORY DRIVER EDUCATION.................................................................................................... 78 5.7 RESTRICTIONS ON NOVICE DRIVERS .................................................................................................. 82 5.8 APPLICATION OF THE PRESENT RESULTS TO LICENSING SYSTEMS IN COUNTRIES OTHER THAN

SWEDEN ........................................................................................................................................................... 84 5.9 FUTURE RESEARCH ............................................................................................................................ 85

6 CONCLUSIONS AND SUGGESTIONS ............................................................................................ 89

ACKNOWLEDGEMENTS .............................................................................................................................. 91

REFERENCES .................................................................................................................................................... 93

ABSTRACT Traffic fatalities and injuries among young drivers as a result of road crashes constitute a serious public health problem. The ultimate goal of traffic safety work in Sweden has been formulated in Vision Zero, which includes an image of a future in which no one will be killed or seriously injured in traffic crashes. Therefore, it is unacceptable that young learner and novice drivers are in‐volved in road crashes that result in fatalities or severe injuries. Driver educa‐tion is an important tool to increase the probability that young drivers actually take their share of the responsibility for Vision Zero by obeying traffic rules and driving as safely as possible. The general aim of the work underlying this thesis was to determine the po‐tential of driver education to reduce road traffic crashes involving young driv‐ers, particularly in Sweden. Paper I examined the relationship between the way in which the education is carried out and the outcome of the driving test. Paper II explored whether there are any gender‐related differences regarding driving practicing, the outcome of the license tests, and involvement in crashes during the first year of licensure. Paper III evaluated the reform that made it possible for learner drivers to start practicing from 16 years of age in terms of its effects on crashes involving young novice drivers. In paper IV, the focus was on investigating crashes during practice and comparing the results with the corresponding situation for novice drivers during their first two years of licensure. Paper V assessed an insight‐based educational approach aimed at inducing young drivers to make better use of vehicle‐related safety equip‐ment. The findings of two of the studies (papers III and IV) showed that, in Sweden, taking advantage of the possibility to start practicing behind the wheel from the age of 16 years had a beneficial effect seen as reduced crash involvement among those young drivers. In paper V, it was revealed that using an insight‐based educational approach can have a positive influence on learner drivers’ knowledge of and attitudes towards the use of car safety equipment (e.g., safety belts). In paper I, it was found that it is difficult to explain why 18–24‐year‐olds pass or fail the driving test on the basis of background variables and information concerning how they had practiced driving. Paper II showed that, for females, training pursued in a more structured manner did not seem to be beneficial for the outcome of the license tests, and that males aged 18–24 were involved in 1.9 more injury crashes per 1,000 drivers than females during their

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first year of licensed driving. Suggestions are given that can be used to de‐velop the Swedish licensing system in a way that will increase the potential of driver education to reduce traffic crashes among young drivers. These ideas comprise aspects such as the following: persuading the youngest learner driver population to start practicing as early and as much as possible; the learning period should be better organized, which includes improved agree‐ment between the goals of the national curriculum, the content/process of driver education, and the design of the license tests; professional instruction of learners in both the theory and the practice of driving should be a more prominent component of driver education; and parts of the Swedish licensing system should be made mandatory to help solve the problems of young driv‐ers and to fulfill the goals of the national curriculum. Keywords: driver education; driver training; learner drivers; novice drivers; young drivers; evaluation; public health; traffic safety; supervised practice; 16 year age limit; safety halls; Sweden; questionnaires; attitudes; knowledge; experience; gender; driv‐ing tests; crashes; crash involvement; crash types; road traffic.

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LIST OF PAPERS The thesis is based on the following papers, which will be referred to in the text by their Roman numerals: I Nyberg, A., Gregersen, N.P., Wiklund, M., 2007. Practicing in rela‐

tion to the outcome of the driving test. Accident Analysis and Preven‐tion, 39(1), 159‐168.

II Nyberg, A., Gregersen, N.P., 2007. Practicing for and performance

on driver’s license tests in relation to gender differences in crash involvement among novice drivers. Journal of Safety Research (in press), doi:10.1016/j.jsr.2007.01.001

III Gregersen, N.P., Berg, H.Y., Engström, I., Nolén, S., Nyberg, A.,

Rimmö, P.A., 2000. Sixteen years age limit for learner drivers in Sweden – an evaluation of safety effects. Accident Analysis and Pre‐vention, 32(1), 25‐35.

IV Gregersen, N.P., Nyberg, A., Berg, H.Y., 2003. Accident involve‐

ment among learner drivers – an analysis of the consequences of supervised practice. Accident Analysis and Prevention, 35(6), 725‐730.

V Nyberg, A., Gregersen, N.P., Nolén, S., Engström, I., 2005. Safety

halls – an evaluation. Journal of Safety Research, 36(4), 429‐439.

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LIST OF FIGURES AND TABLES Figures Figure 1. Driver fatalities per 100,000 license holders (private vehicles) in different age groups in Sweden 1994–

2005......................................................................................................................................................... 9 Figure 2. Severely injured drivers per 100,000 license holders (private vehicles) in different age groups in

Sweden 1994–2005................................................................................................................................. 9 Figure 3. Driver fatalities per 100,000 license holders (private vehicles) in different age groups and according to

gender in Sweden 1994–2005................................................................................................................ 11 Figure 4. Severely injured drivers per 100,000 license holders (private vehicles) in different age groups and

according to gender in Sweden 1994–2005. ......................................................................................... 11

Tables Table 1. Goals for Driver Education (GDE) matrix. ............................................................................................ 29 Table 2. Summary of materials and methods used in the five studies. .................................................................. 41 Table 3. Full model explaning the outcome of the driving test. ............................................................................ 57 Table 4. Differences in crashes per 1,000 drivers and crashes per 10 million km driven between the 16-year-old

group and the two controlgroups with and without controlling for confounding factors....................... 62

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DEFINITIONS Accident/Crash: In this thesis, the terms accident and crash mean the same thing,

namely, a road traffic crash leading to fatalities or personal injury. Evans (1991) recommends the word crash, because in his opinion the term accident may cause people to think that such events occur due to fate and therefore are unpredictable and unpreventable. However, both terms are still used in literature, as well as in everyday language.

Accident/Crash risk: Number of accidents/crashes per kilometre driven (unless oth‐erwise defined).

Driver education/Driver training: In this thesis these terms are used synonymously and involves formal and informal education/training as well as both theoretical studies and behind‐the‐wheel practice.

Health risk: Number of accidents/crashes per license holder (unless otherwise de‐fined).

Lay instructor: A non‐professional person with permission to supervise a learner driver during practice, usually the father and/or mother of the learner.

Learner driver: A driver without a full license but with permission to practice under supervision.

Novice driver: A person that recently qualified for a driving license, regardless of biological age.

Professional instructor: A person specially educated to teach driving and usually employed at a driving school or at a skid track.

Safety hall: A specially designed facility at some skid tracks designed to give learn‐ers knowledge about the various types of safety equipment in motor vehicles, why they should be used, and how to use them in a correct manner.

Skid track: An enclosed, specially designed area where learners perform the part of the mandatory risk awareness education that involves low‐friction driving.

Young driver: A driver 18–24 years old (unless otherwise defined). OLY/VITS: The Swedish National Road Administration Information System for Traf‐

fic Safety, which is a national crash database. NTF: The Swedish National Society for Road Safety. STAPRO: Database comprising, among other things, results of the license tests. STRADA: Swedish Traffic Accident Data Acquisition, which is also a national crash

database. S(N)RA: Swedish (National) Road Administration VINNOVA: The Swedish Agency for Innovation Systems VTI: Swedish National Road and Transport Research Institute

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Background

1 BACKGROUND This thesis concerns the potential of driver training to reduce road traffic crashes and severe injuries among young drivers, with special focus on Swe‐den. The present research was conducted in order to draw attention to the fact that traffic fatalities and injuries among young drivers constitute a serious public health problem (OECD, 2006). It also examins the principle manifested in the Swedish Vision Zero, which anticipates a future in which no one will be killed or seriously injured in road traffic crashes. Vision Zero further states that the responsibility for traffic safety is shared by those who design and those who use the road transport system. Nonetheless, the burden is primarily on the former group in this context, because if the road users do not abide by the laws and regulations, it is the task of the system designers to solve that problem (SRA, 2006; Tingvall, 2005). It can be allotted to the system designers to draw up plans for the road environment and the laws and rules to be ap‐plied both in the traffic system and by those who provide driver education. Therefore, driver training is an important tool to increase the probability that young drivers actually take their share of the responsibility for Vision Zero by obeying traffic rules and driving as safely as possible. The background of the problems connected with young drivers is introduced in this chapter, along with ideas about how these issues might be solved through driver training. Also, the Swedish system for obtaining a class B driv‐ing license is described, because, in one way or another, all the papers in‐cluded in this thesis give information about how that system works or how it might be improved.

1.1 Traffic fatalities and injuries—a serious public health problem

About 127,000 people are killed and more than two million are injured in road traffic crashes each year in the European Region of the World Health Organi‐zation, WHO. This problem is especially pronounced in the age group 15–29 years, in which traffic crashes are the leading cause of death. Traffic crashes and related fatalities and injuries represent a major public health problem and lead to substantial costs to society, not only in Europe, but in all parts of the world (Racioppi et al., 2004). Notably, in the OECD countries, such crashes are

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Background

the primary cause of death among 18–24‐year‐olds, and they account for 35% of all deaths among 15–24‐year‐olds (OECD, 2006). Expressing the public health problem as disability‐adjusted life years (DALYs) has shown that road traffic injuries ranked ninth among all public health prob‐lems in the world in 1990, and it has been predicted that they will be in third place by 2020 (Murray & Lopez, 1996, Krug, 1999; WHO, 2004).

1.2 Involvement of young drivers in crashes

1.2.1 Fatalities and severe injuries In Sweden, during the period 1994–2005 an average of 518 people were killed annually in road traffic crashes (crash deaths due to disease excluded). Among people aged 18–24, the corresponding average number of deaths was 82, in‐cluding 42 killed while driving a car and 20 as passengers. Also during the same time period, an average of 4,102 people were severely injured in road traffic crashes; 756 of those individuals were 18–24 year olds, and of them 336 had been driving the vehicle during the crash and 191 had been passengers. This means that, on average, a little more than 75% of all deaths and almost 70% of all severe injuries due to road traffic crashes among 18–24‐year‐olds occurred while the individuals were traveling in a private motor vehicle (Brüde, 2005; Forslund, 2006). Figure 1 shows that traffic fatalities are a major problem among 18–24‐year‐old drivers. Comparing that group (the youngest) with drivers aged 25–64 indi‐cated that the probability of being killed as a driver was on average 2.95 times higher (min. 1.98, max. 3.68) in the former group. In addition, compared to the oldest age group, individuals in the youngest group were 1.96 times more likely to be killed as a driver (min. 1.01, max. 2.97). As can be seen in Figure 2, severe injuries due to traffic crashes are also a ma‐jor problem among 18–24‐year‐old drivers. Comparing that age group with those aged 25–64 shows that the probability of being severely injured as a driver was on average 2.92 times higher (min 2.25, max 3.50) in the former group. Also, the probability was 4.11 times higher (min. 2.53, max. 5.98) for the youngest drivers when comparing them with the oldest age group.

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Background

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Figure 1. Driver fatalities per 100,000 license holders (private vehicles) in different age groups in Sweden 1994–2005. No data regarding license holders were available for the year 1999. All crash fatalities due to disease were excluded. Sources: Forslund (2006) and Lekander (2006).

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Figure 2. Severely injured drivers per 100,000 license holders (private vehicles) in different age groups in Sweden 1994–2005. No data regarding license holders were available for the year 1999. Sources: Forslund (2006) and Lekander (2006).

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Background

Figure 3 shows that the traffic fatality problem is especially pronounced for the youngest male drivers, who were on average at 2.98 times higher risk (min. 1.84, max. 3.70) of being killed as a driver compared to male drivers aged 25–64. Compared to the oldest males, the risk was 2.01 times higher (min 1.06, max 3.15) in the younger group. Also, the probability of being killed as a driver was on average 4.09 times higher (min 2.65, max 6.21) for young male drivers than for their female counterparts. However, even though young fe‐male drivers were much less crash prone compared to males, the probability of being killed as a driver was still on average 2.59 and 2.14 times higher for females aged 18–24 than for females in the age groups 25–64 and 65+ years. Data from a number of different OECD countries show that male drivers aged 18–24 are involved in fatal road crashes three times more often (per million population) than female drivers in the same age group (OECD, 2006). Even when exposure is accounted for, the gender differences related to young nov‐ice drivers persist, as has been shown by, among others, Kweon and Kockel‐man (2003) in the United States and other investigators analyzing data col‐lected in the Netherlands, Sweden, and the United Kingdom (Lynam et al., 2006). Kweon and Kockelman (2003) found that the crash risk per million miles was 1.2 times higher for male than for female drivers less than 20 years of age. Lynam et al. (2006) found that 18–24‐year‐old male drivers had over three times more fatal crashes per million kilometers driven. With regard to severely injured drivers, the problem is again especially pro‐nounced for young males. Considering the data in Figure 4, the probability of drivers being severely injured was on average 3.27 times higher (min. 2.52, max. 3.88) for the youngest males than for males aged 25–64. In addition, compared to the oldest males (65+ years), the likelihood of severe injury was 4.10 times higher (min. 2.51, max. 6.17) for the youngest male drivers. Also, the probability of being severely injured as a driver was on average 2.11 times higher (min 1.70, max 2.71) among young male drivers than among their fe‐male counterparts. Notwithstanding, the probability of being severely injured was on average 2.26 and 4.51 times higher for the youngest female drivers compared to female drivers aged 25–64 and 65+ years, respectively.

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Background

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1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

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Males 18–24 Females 18–24 Males 25–64Females 25–64 Males 65+ Females 65+

Figure 3. Driver fatalities per 100,000 license holders (private vehicles) in different age groups and according to gender in Sweden 1994–2005. No data regarding license holders were available for the year 1999. All crash fatalities due to disease were excluded. Sources: Forslund (2006) and Lekander (2006).

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Figure 4. Severely injured drivers per 100,000 license holders (private vehicles) in different age groups and according to gender in Sweden 1994–2005. No data regarding license holders were available for the year 1999. Sources: Forslund (2006) and Lekander (2006).

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Background

To further illustrate the extent of the problem, it can be mentioned that during the years 1994–2005, 19% of all those who were killed and 21% of those who were severely injured in road traffic crashes involving private vehicles were young novice drivers. These rates are very high, since on average only 8% of all licensed drivers during the mentioned period were young novice drivers (Forslund, 2006; Lekander, 2006). The description so far has focused on the outcome for the young drivers them‐selves. However, the problem associated with these vehicle operators is even more preponderant when considering that they are involved as drivers in many more fatal crashes in which they are not the ones who are killed. On av‐erage, 94 young drivers aged 18–24 were involved in 85 fatal crashes in Swe‐den over the years 1996–2005. In those crashes, an average of 100 people were killed, and 42 of them were the young drivers themselves (Björketun, 2006; crash fatalities due to disease excluded). This means that for every young per‐son who was killed in a crash as a driver, on average 1.38 other road users died. During the same time period, on average 618 drivers aged 18–24 were involved in 544 crashes that led to severe injuries in 950 people, and 345 of those individuals were the young drivers themselves (Björketun, 2006). This indicates that for every young person who was severely injured when in‐volved in a road crash as a driver, on average 1.75 other road users were se‐verely injured. These figures are similar to data collected in the Netherlands showing that for every young driver (18–24 years of age) that was killed in a crash, about 1.33 other road users died; and for every young driver who was severely injured, about 1.8 other road users sustained severe injuries (OECD, 2006). Crashes that occur during driving practice have not been investigated to any significant extent, and the study reported in paper IV was one of the first at‐tempts to distinguish between crashes involving learners and newly licensed drivers. However, in a Swedish study by Berg et al. (2004) which investigated the circumstances of occurrence of crashes during driving practice, it was found that efforts should be taken to reduce the youngest learners’ crashes in rural areas on high speed roads. Also, the EU project designated BASIC (Hatakka et al., 2003) has reported that surveys covering all crashes during practicing (even those involving minor vehicle damage) that have been con‐ducted in Finland, Norway, Sweden, and the United Kingdom have shown that learner drivers are involved in very few crashes. This agrees with esti‐mates published by Forsyth et al. (1995) indicating that the crash rate is at least

12

Background

20 times higher during the first year of licensed driving than during the learn‐ing period. To summarize, the over‐involvement of young drivers (especially young males) in traffic crashes is a considerable problem, both from the perspective of public health and in terms of road safety (OECD, 2006).

1.2.2 Crash types and circumstances related to injury crashes involving young novice drivers

Young novice drivers are overrepresented in most types of road crashes. However, involvement of this group is more extensive in certain kinds of crashes, and, in many countries, the highest overrepresentation is found in single‐vehicle crashes and loss‐of‐control crashes. For example, in the US state of Maryland, single‐vehicle crashes have been found to constitute 25.6% of all vehicle crashes involving 16‐year‐old drivers (Ballesteros & Dischinger, 2000). In Sweden, Gregersen and Nyberg (2002) found that during the years 1994–2000, 27% of the traffic crashes involving 18–19‐year‐old drivers were single‐vehicle crashes, whereas the corresponding rate for all other ages groups was 14%. Considering single‐vehicle crashes involving fatalities, the rate was 32% in the youngest age group compared to 24% among drivers of all other ages. Also, Clarke et al. (2001) have observed that in the United Kingdom 22% of road crashes involving 17–19‐year‐old drivers have been single‐vehicle crashes. The overrepresentation of young novice drivers is also evident when consider‐ing loss‐of‐control crashes. For example, Harrison et al. (1999) found that 18% of causal injury crashes involving young drivers entailed loss of control of the vehicle. Similar findings have been reported by Laapotti and Keskinen (1998) and Clarke et al. (2002). It is also well known that young novice drivers are overrepresented in crashes that occur at night on weekends, as observed by, for instance, Gregersen and Nyberg (2002) in Sweden, Laapotti and Keskinen (1998) in Finland, Williams (1985) in the United States, and the OECD (2006) in Australia. As an example, 32% of crashes involving 18–19‐year‐old drivers in Sweden in 1994–2000 hap‐pened in darkness (Gregersen & Nyberg, 2002), whereas the corresponding rate for drivers in all other age groups was 22%. Clarke et al. (2006) found that young drivers 17–25 years old were particularly prone to crashes caused by

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Background

loss of control of the vehicle on curves and in darkness. Those investigators also noted that young male drivers were more often responsible for rear‐end crashes, whereas young females were more frequently the drivers of the cars that were hit. Clark and colleagues also noted that the identified problems were greatest for 17–19‐year‐old males. Furthermore, they observed that, with regard to the likelihood of crashes, there was generally an improvement over time, that is, the older the driver the less the chance of being involved in a road crash. It is well established that speeding is a major factor related to car crashes in‐volving young novice drivers—the higher the speed the greater the risk of los‐ing control of the vehicle. Moreover, since younger drivers also tend to have more passengers in the car, if an crash does occur, more people will be injured and the outcome of the crash will be more severe (e.g., Evans, 1991; Twisk, 1994). In the United Kingdom, speeding has been found to be by far the most common offense among young drivers, as reported by Forsythe et al. (1995). Also, observational studies performed by Waylen and McKenna (2002), showed that younger license holders drove significantly faster than those who were older. McKnight and McKnight (2000) have estimated that speeding ac‐counts for 20% of all crashes in the US states of California and Maryland. In Australia, Harrison et al. (1999) observed that speeding was more frequently done by young drivers (especially males) than by those who were older. Simi‐larly, in a large‐scale study conducted in Europe by Goldenbeld (1999), young male drivers in particular reported that, compared to older drivers, they drove faster and also more often over the legal speed limit. In an investigation by Neyens and Boyle (2007), it was found that young drivers who were speeding or had been drinking alcohol were more likely to be involved in crashes with fixed objects than with other vehicles. Data covering 1983–2002 obtained in the United States have revealed that individuals younger than 25 represent the largest proportion of drivers known to be speeding when fatal crashes oc‐curred (OECD, 2006). In that study, it also became apparent that the problem of speeding is clearly most pronounced among young male drivers, although speeding does seem to be a male problem at any age. Alcohol has also been found to play an important role in crashes involving young drivers. This is very interesting when considering that it has not been established that young drivers are more inclined than older drivers to operate a vehicle while under the influence of alcohol (Forsman & Gustafsson, 2004). Nonetheless, young drivers (typically young men) are overrepresented in al‐

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Background

cohol‐related crashes, usually in combination with high speed, night‐time driving, and the presence of passengers (e.g., Brorsson et al., 1993; Schulze, 1996; OECD, 2006). Data compiled in Sweden in 2002 have shown that the drivers in 63 car crashes that led to fatalities had been drinking alcohol, and 35% of those drivers were 18–24 years old, even though this age group ac‐counted for only 7% of the licensed drivers in the country at that time (SRA, 2004a). A plausible explanation for that observation is that, with each drink consumed, the risk of fatal injuries increases more rapidly in young people than in those who are older (Glad, 1985; Keall et al., 2004). Beirness and Simp‐son (1991) and Shope (1997) have reported that, compared to drivers who have not had any crashes, those who have been involved in crashes are overrepre‐sented with regard to factors such as the use of alcohol and other intoxicating substances. Corfitsen (1994), Pack et al. (1995), and Horne et al. (2002) have all concluded that tiredness is an important cause of many crashes involving young male drivers. Furthermore, findings reported by Åkerstedt and Kecklund (2001) in‐dicate that the crash risk for drivers aged 18–24 is 5–10 times higher at night compared to before noon. A logical explanation for these observations is that young drivers have little experience and knowledge of how to cope with fa‐tigue compared to older, more experienced drivers (Summala & Mikkola, 1994). Based on reviews of research on factors such as sleep loss and sleeping habits, Groeger (2006) hypothesized that drowsiness may have a major impact both on crash involvement among young drivers during darkness and the early hours of the morning and on problems associated with learning to drive. This hypothese was based on the findings that the youngest age group exhib‐its the largest difference between the actual amount of sleep they get and the amount that they really require and/or desire. It is often emphasized that the presence of passengers, particularly passengers of a similar age, increases the risk of crash involvement in young novice driv‐ers. It has been suggested that this problem is sometimes due to the driver be‐ing affected by group pressure from the passengers and that at other times it is the result of the driver being distracted by the passengers. In an instrumented vehicle study conducted by Engström (2003), it was found that young male passengers tried to influence a young male driver (by egging on or mocking) to act dangerously in different ways (e.g., to drive faster, to overtake another vehicle, or to test the performance of the car). The results showed that in most cases the driver resisted the pressure from the passengers and that the mean

15

Background

speed was higher when the driver was alone than when there were passengers in the vehicle. In another study, Engström et al. (2006) observed that passen‐gers had a protective effect, regardless of the age or the gender of the driver, and that influence was lowest on drivers (particularly males) who were 18–24 years of age, although even in this age group the crash risk was higher for those driving without passengers. These findings are contradicted by other research results, especially analyses of data collected in the United States showing that the crash risk is higher in the presence of same‐age passengers or increasing numbers of passengers (e.g., Preusser et al., 1998; Williams, 2000; Chen et al., 2000). This discrepancy might be explained by the cultural differ‐ences between the United States and Sweden, or that the drivers in the young‐est age group in Sweden were a little older than those included in the US stud‐ies (who were 16–19 years old). Obviously, there are also many other factors that might divert the attention of young drivers. For instance, Gregersen and Falkmer (2003) have pointed out that in‐vehicle support systems may have a distracting and negative impact on traffic safety, particularly for young novice drivers, since it is reasonable to expect that that group will be affected by problems such as a higher mental workload, a tendency to overestimate the in‐vehicle support systems, or other motives associated with their way of operating a motor vehicle. These authors concluded that the support systems may very well be beneficial for the safety of young licensees, although little research has been done to address that is‐sue. Therefore, to be able to exploit in‐vehicle aids in the best way possible as a means of enhancing traffic safety for young drivers, further studies will have to be carried out to determine how drivers in this age group make use of such systems (e.g., regarding level of acceptance, utilization, and overconfidence). This reasoning is in line with explanations put forward by Sarkar and Andreas (2004) stating that young drivers tend to overestimate their ability to handle new technological devices while driving. Also, Neyens and Boyle (2007) found evidence that the rate of crashes with fixed objects will increase among young drivers confronted with in‐vehicle distractions (e.g., adjusting controls and eating). Furthermore, those researchers noted that rear‐end collisions are more likely to happen if the driver is cognitively distracted or if there are distur‐bances related to passengers or a cell phone. The above‐mentioned overrepresentation of young novice drivers in crash sta‐tistics is magnified by the fact that a disproportionately large number of those individuals are included in the group of drivers who do not use a seat belt.

16

Background

Again, this is seen primarily in young male drivers, and in Sweden the lower rate of seat belt wearing has been found both in observational studies (Ceder‐sund, 2006) and in two in‐depth investigations of fatality crashes (SNRA, 2003; SRA, 2004b). In the SRA study from 2004, it was found that 40% of 18–24‐year‐olds killed in car crashes had not worn a seat belt. Among 18–25 year olds in Sweden the average general rate of usage between the years 2000–2005 was 81% for males and 93% for females (Cedersund, 2006). Similar findings have also been made in other countries (e.g., Goldenbeld, 1999; NHTSA, 2001; Cvijanovich et al., 2001; Williams & Shabanova, 2002; Williams et al., 2003; McCartt & Shabanova Northrup, 2004). The seat belt is the piece of safety equipment known to most effectively minimize the severity of injuries caused by a crash. Hence the lower rate of seat belt wearing among young drivers is no doubt one reason why these individuals are overrepresented in crash‐related injury statistics.

1.3 Factors essential for understanding the prob‐lems of young drivers

This section gives a brief overview of aspects connected with decision making, driving behavior, and the involvement of young novice drivers in road crashes, especially with respect to factors behind many of the problems ex‐perienced by this group of licensees. It is also important to point out that the problems affect all novice drivers regardless of gender, although they have a greater impact on males. It is generally assumed that the three main factors in this context are age, experience, and gender. However, it is also worth men‐tioning that there is interaction and overlap between these three factors and between the underlying causes and processes (e.g., individual and social cir‐cumstances) (OECD, 2006).

1.3.1 Age and experience The effects of age and experience are very important for the outcome of both the learning period and the time as a novice driver. Studies have shown that the older driver is when she/he obtains a license, the lower the risk of initial crash involvement as a novice driver (e.g., Cooper et al., 1995; OECD, 2006). It has also been established that the process of acquiring experience has a sub‐stantial impact on the outcome during the first period as a licensed driver. For example, Sagberg (2000) and Mayhew et al. (2002) have shown that there is a sharp reduction of crashes (by 40–50%) among novice drivers during their first

17

Background

seven to eight months of licensed driving. In addition, Maycock, et al. (1991) found that both age and experience have an effect; more precisely, these re‐searchers studied recent licensees and noted that the rate of crash involvement decreased with age and with increasing experience of the driver. Nevertheless, results vary in this context. It seems that factors related to age account for 30–50% of the crash reduction during the first period of independent driving, and the corresponding rates for the factors associated with experience are in the range 50–70% (Gregersen, 2003). Notably, it is also clear that age‐related fac‐tors have a more pronounced effect the lower the age limit is for obtaining a driver’s license (e.g., a person can obtain a license at the age of 16 years in mo‐st US states). Even so, many reviews have revealed that the lack of experience is one of the primary factors contributing to crash involvement among novice drivers (e.g., Lynam & Twisk, 1995; Mayhew & Simpson, 1996; Engström et al., 2003; OECD, 2006). In the report published by the OECD (2006), it was con‐cluded that the findings of many studies indicate that experience is more im‐portant than age when trying to explain why young drivers have high crash rates during early licensure. Therefore, it is important that aspiring drivers are given the opportunity to gain as much experience as possible during the learning period, before they get a license. This conclusion is supported by two studies in which it was found that driving skills improved as a power function of the amount of be‐hind‐the‐wheel practicing done by a learner (Groeger & Clegg, 1994; Groeger & Brady, 2004), and also by an investigation showing that simply gaining driv‐ing experience is an important part of learning to operate a motor vehicle (Maycock & Forsyth, 1997). The latter study showed that males that had actu‐ally driven more during the learning period had lower rates of crash involve‐ment compared to males that had been awarded a license within a relatively short period of time without much behind‐the‐wheel training. The importance and potential safety benefits of gaining experience constituted one of the main arguments behind the decision to lower the age limit for practicing in Sweden from 17½ to 16 years. Inasmuch as the age for licensing is still 18, this legisla‐tive change resulted in the possibility of acquiring supervised experience be‐hind the wheel for a period of two years before driving alone as a license holder. This reform was evaluated in the study reported in paper III.

18

Background

1.3.2 Gender differences Clearly, even though the crash risk is generally higher for young drivers than for those who are older and more experienced, the problem is most alarming for young males. It has been suggested that the gender difference in crash in‐volvement among young novice drivers is associated with several factors, such as the following tendencies exhibited by many young males: being more prone to sensation seeking and therefore more reckless when driving (Jonah, 1996; Clarke et al., 2005; Groeger & Brown, 1989); overestimating their driving ability (Gregersen, 2003); having a higher degree of risk acceptance while driv‐ing (Deery, 1999); driving in “difficult” situations, such as bad weather and late at night (Forsyth et al., 1995); driving faster (Waylen & McKenna, 2002); driving while intoxicated (Begg et al., 1999); having more passengers in the car, which increases exposure to peer pressure (Rolls & Ingham, 1992; Lapotti et al., 1998); being less safety‐oriented (Meadows & Stradling, 1999; Laapotti, 2003); being more prone in violating formal and informal traffic rules (Rimmö, 1999); having a lifestyle associated with risky driving behavior (Schulze 1990; Gregersen & Berg, 1994); having different goals for their driving and generally driving more frequently and consequently being affected by more situations (Gregersen, 1998; Laapotti, 2003).

1.3.3 The impact of experience on development of skills

Research has shown that to be able to drive safely, it is necessary to become experienced in the tasks involved in operating a motor vehicle. A driver’s mental workload, visual search skills, and capacity for hazard perception are to a large extent connected with driving experience. Therefore, these factors have been shown to be problematic for learners and novice drivers (e.g., Gre‐gersen, 2003), and it is also believed that they can partly explain why it is es‐sential to have driving experience. As a driver gains experience, more tasks—both motorized and visual—will become wholly or partly automatized, and his/her ability to perform an in‐creasing number of exercises simultaneously will gradually improve. These processes can be described on the basis of a theory formulated by Rasmussen (1986), which considers human behavior in terms of the way that individuals control their own actions on three different levels in relation to the develop‐ment of skills. The level that a person makes use of is decided by the experi‐

19

Background

ence that she/he has of the task to be solved. In the context of driving a motor vehicle, an inexperienced driver or one who encounters unfamiliar situations acts on a knowledge‐based level, implying that actions are preceded by conscious decisions that resemble problem solving. On this level, the driver has no ready solutions at hand, and the decisions emanate from, for instance, the person’s own know‐how and previous experiences of other situations (e.g., riding a bi‐cycle). The more experienced a driver becomes, the greater the number of driving tasks and traffic situations that will be familiar and recognized. In other words, the driver gradually accumulates a repertoire of behavioral patterns that can be used to solve and handle traffic tasks and situations that resemble each other. That is, a certain driving situation will be associated with a particu‐lar pattern of behavior. Decisions on this rule‐based level will be more or less unconscious and automatized. After extensive driving experience, a driver can process a large amount of in‐formation on an unconscious level. This means that many tasks are done automatically without the driver being aware of what information he/she has used to make decisions or take actions. This skill‐based level requires very little conscious attention on the part of the driver. It should be emphasized that the majority of drivers switch between all three levels while operating a motor ve‐hicle, and it is the experience of the driver and the traffic system as a whole that determine the level on which most of the driving is performed. Another important issue that is closely related to the discussion above is the extent to which tasks involved in driving make demands on the driver’s men‐tal capacity. It has been suggested that one explanation why experienced driv‐ers are better than inexperienced drivers at managing traffic situations is a de‐creased mental workload (Gregersen, 2003), which can be achieved by more extensive practice behind the wheel. If decisions and actions are largely auto‐matized because a driver is very experienced, then a limited amount of mental resources is needed to operate the vehicle. However, it is not only these me‐chanical aspects that are of importance. The more experienced a driver is the easier it is for him/her to recognize and interpret different traffic situations and on the basis of that develop “mental models” that can facilitate processing of the information and use of the available mental resources. Thus, the size of the mental workload is influenced by the degree to which driving has become automatized and the particular mental models that have become established.

20

Background

For instance, mental resources are required to solve each subtask correctly, and the driver’s capacity in that respect determines how many subtasks can be fulfilled simultaneously. Therefore, to drive safely, it is necessary to be able to make use of the controls in the vehicle (e.g., the steering wheel, clutch, gear lever, and brake and accelerator pedals) and at the same time interact with other motor vehicles and road users, adapt to changes in the road environ‐ment, and take into account both formal and informal traffic rules. This means that a driver must be able to very rapidly process and interpret all pertinent information outside the vehicle and react in accordance with the specific situa‐tion at hand (e.g., by applying the brakes or changing direction) to continue to be in control of what is happening. An inexperienced driver needs extensive mental resources to solve fairly “simple” tasks (e.g., shifting gears), which means that insufficient resources are left to solve all other tasks satisfactorily. This complexity of information processing in humans has been described by, for example, Wickens (1992). Various approaches have been used to investigate the ways that drivers deal with the mental workload as they become more experienced. Patten et al. (2006) applied a secondary task method in a field study, and they were able to verify the above‐mentioned theory proposed by Rasmussen (1986) indicating that driving experience reduces the mental workload on the driver. Patten et al. (2006) suggests that this finding can be particularly important for learners, since the abilities needed to be able to drive safely must be acquired cogni‐tively (e.g., in different traffic situations) and as motor skills (e.g., being able to handle the vehicle). Also, in a study performed in real traffic situations to evaluate the Swedish reform lowering the age limit for driving practice to 16 years (Gregersen et al., 2000; Nyberg & Nolén, 2001), it was observed that young novice licensees who had gained more driving experience as learners reported a lower mental workload compared to those who were less experi‐enced. Similarly, Shinar et al. (1998) found that inexperienced drivers did not detect road signs as well as experienced drivers did when driving a car with a manual transmission compared to an automatic transmission. This finding was interpreted as showing that gear shifting is a task that becomes automa‐tized over time, or, in other words, that a novice driver will have to use most of his/her mental resources to shift gears so that there will not be enough left to detect road signs. Falkmer and Gregersen (2005) have found that, compared to experienced driv‐ers (i.e., those with more than 100,000 km of licensed driving), inexperienced (learner) drivers more often fixated on objects inside the vehicle, on things of

21

Background

relevance in the traffic, and on entities constituting potential hazards in the traffic environment, and they spread their fixations less on the horizontal me‐ridian. Furthermore, although some results are contradictory, research has shown that there are differences between novice and experienced drivers, at least with regard to visual search skills (e.g., Mourant & Rockwell, 1972; Miltenburg & Kuiken, 1990; Falkmer & Gregersen, 2001; Åberg, 1981; Chap‐man & Underwood, 1998; Williams, 1985), and this is generally believed to be related to the mental workload. Hazard perception entails the ability to discover, recognize, and react to po‐tentially dangerous situations, and investigations on that subject have also in‐dicated that mental workload is one of the most important aspects to consider when trying to understand the difficulties that novice drivers encounter in traffic. For instance, several studies have provided evidence supporting the notion that automation and mental workload can explain differences between novice and experienced drivers with regard to how fast they detect hazards in the traffic environment (McKenna & Crick, 1991; Drummond, 1995; Renge, 1998). However, McKenna and Farrand (1999) concluded that the opposite was true, because they found that experienced drivers performed less satisfac‐torily than novice drivers did when required to carry out a secondary task at the same time as trying to detect hazards. Also, Sagberg and Bjornskau (2006) administered a video‐based hazard perception/reaction test to groups of driv‐ers who had had licenses for different periods of time, and their results did not show that reaction times decreased significantly with increased driving ex‐perience. Accordingly, those authors concluded that research findings indicat‐ing a rapid reduction in crash risk during the first months of licensed driving can probably be explained to only a small extent by improvement in hazard perception skills.

1.3.4 Individuals’ own estimations of their compe‐tence as drivers

Many investigations have shown that overconfidence is a real problem among novice drivers (e.g., Spolander, 1983; Matthews & Moran, 1986; Gregersen, 1996; McKenna et al., 1991; McKenna, 1993; Deery, 1999; Nolén & Nyberg, 2001). The findings of those studies imply that new licensees have an incorrect perception of the level of their own ability to operate a motor vehicle, so that they believe they are much better drivers than they actually are. This false conception is especially widespread among young male drivers, which in turn

22

Background

suggests that those individuals find it difficult to assess dangers and risks in traffic. Therefore, overconfidence may explain why novice drivers are more apt than long‐term licensees to commit violations such as speeding, not wear‐ing a seat belt, and driving too close to the vehicle in front. One explanation for this difference is that the new license holders think they can get away with the transgressions, because in their own opinions they are such excellent driv‐ers. For the same reason, they feel that even if something unexpected happens, they can manage to avoid a crash. However, Groeger (2006), among others, has argued that young drivers have a sounder apprehension of their driving ability than more experienced drivers do. This researcher means that the prob‐lems in many questionnaire studies are associated with methodology issues, because subjects are usually asked to compare themselves with an “average” driver instead of a driver that is more similar to themselves. Not surprisingly, opinions vary as to how responses are affected by different ways of posing questions, although experimental investigations have shown that young li‐cense holders do overestimate their ability to drive (e.g., Gregersen 1996; Nolén & Nyberg, 2001).

1.3.5 Individual and social preconditions Factors such as social norms, lifestyle, personality, socio‐economic factors, and reasons for driving have been found to be associated with the problems ex‐perienced by young drivers. Most of these aspects are related to life in general, but despite that they influence the attitudes, decisions, and behavior of indi‐vidual drivers when driving a car (e.g., Hatakka et al., 2002; Engström et al., 2003; OECD, 2006). When young people are first learners and later novice drivers, they are going through a period in life that involves a wide variety of changes. For instance, many of them are in the process of becoming independent, which includes testing limits and breaking free from influences and expectations from people whose values and norms have previously been very important in their lives (e.g., parents). Of course, these elements do still have a substantial impact (see below regarding the influence of parents), but in most cases other influences are of growing importance, including things like peer group norms and im‐ages of the way young people ought to be that are portrayed by the media, popular culture, and society. These social standards have been found to have a pronounced impact on decision‐making process and thus they also influence

23

Background

young people’s ways of behaving as drivers of motor vehicles (e.g., Engström et al., 2003). What is known as “the theory of planned behavior” stresses the importance of social norms for the actual actions of an individual (Ajzen, 1991). The social norms are not considered to be some kind of standards that are valid for and accepted by all persons in a society, but instead as subjective norms that a per‐son believes to exist in relation to significant others. This means that a person can feel pressured into exhibiting a particular behavior that is common to a group of people who are important to that individual. For instance, a driver who is closely associated with a group that likes speeding is also likely to speed, regardless of whether she/he knows that speeding is dangerous or really feels inclined to speed. The subjective norms have been found to have a substantial impact on young drivers, in other words their driving behavior is highly influenced by social pressures from friends or peer groups (Berg, 2001, Evans, 1987; Jessor, 1987, Møller, 2004). Even if many young people are in the process of breaking free from their par‐ents at the time they start driving, there is also evidence that they are affected by their parents’ driving behavior. Wilson et al. (2006) found an increased risk of at‐fault collisions during the first three years of licensed driving by young people whose parents had been involved in such collisions or had committed speeding offences or other moving violations during the four years prior to their children’s licensure. Therefore, those investigators concluded that it is important to inform parents about their role in influencing their children’s driving behavior and risks. Similar findings indicating that the driving behav‐ior of parents is passed on to their children have been reported by other re‐searchers, such as Taubman‐Ben–Ari et al. (2005), Bianchi and Summala (2004) and Ferguson et al. (2001). Also, one study has shown that young drivers that have poor relationships with their parents and other adults (e.g., teachers) are overrepresented in crashes (Beirness & Simpson, 1991), whereas Shope (1997), among others, found evidence that living with both parents is a protective fac‐tor. In Sweden, investigations conducted by Murray (1998), Berg et al. (1999), and Hasselberg and Laflamme (2003) have shown that knowledge of socio‐economic factors is needed to understand the problems of young drivers. Murray (1998) observed that the level of crash involvement among young drivers was higher for those who had low grades in school, particularly in

24

Background

theoretical subjects, and also for those who were members of farming and blue‐collar families, as compared to white‐collar families. Berg and coworkers (1999) found that a learner’s permit was obtained by more youngsters in white‐collar families than in blue‐collar families. Those authors concluded that teenagers in blue‐collar families are unfairly affected by the cost of driving practice, since most of the participants in their study had given responses indi‐cating that they could not afford to obtain a learner’s permit. Hasselberg and Laflamme (2003) reported that young drivers whose parents were lower‐income white‐collar workers, blue collar workers, farmers, or entrepreneurs suffered more injuries than did young drivers whose parents were middle‐ and high‐income white‐collar workers. Another important aspect is that there are different motives and goals for driv‐ing a motor vehicle, which influences the risk of being involved in crashes. Gregersen and Berg (1994) found that high‐risk drivers were characterized by a lifestyle that included driving behaviors such as showing off and sensation‐seeking. In another study, Møller (2004) noted that risk‐taking behavior repre‐sents one way of achieving status and position in the group that is of impor‐tance to the driver. It has also been shown that motivation for driving is influ‐enced by the situation in which the driving takes place, for example, a person can drive aggressively in the company of peers but more sensibly in the pres‐ence of parents or children (e.g., Rolls & Ingham, 1992). In 1988, Klemenjak and Hutter (cited in Gregersen, 2003) found that “disco fans” drove less safely when they went to dances on the spur of the moment late in the evening than when they spent the whole evening at such nightspots. The reason for this dif‐ference was assumed to be that the spur of the moment decisions were more often made after imbibing alcohol and also frequently entailed driving long distances to reach the disco. In agreement with that, are results reported by Schulze (1990). Clarke et al. (2006) suggest that crashes that occur during darkness and involve drivers 17–25 years of age are not related to poor visibil‐ity but rather to the driving behavior of the young licensees under these cir‐cumstances, meaning that many of the crashes are due to voluntary risk be‐haviors displayed during ‘recreational’ driving. Personality is an aspect that has also been found to influence driving behavior and consequently the crash risk (e.g., Ulleberg, 2002; Gregersen, 2003; OECD, 2006). Extensive research has been conducted to discern consistent associations in this context. Factors such as social deviance, aggression, impulsiveness, hos‐tility, emotional liability, and low altruism have been found to be related to

25

Background

crash involvement and dangerous driving. However, although some connec‐tions between personality and crash involvement have been detected, most of them have been weak. Nevertheless, sensation‐seeking has been observed to be strongly correlated with the occurrence of crashes. For instance, Jonah (1997) reviewed 31 studies on this subject and found that sensation‐seeking and driving style showed a fairly substantial correlation (0.30 to 0.40) with crash involvement. The aspect of sensation‐seeking has also been noted to be of importance when trying to explain why people violate traffic regulations. For instance, Rimmö and Åberg (1999) showed that violations were associated with high sensation seeking. The OECD (2006) has concluded that there is a weak but consistent association between personality traits and crash involve‐ment, although there is a stronger relationship between personality traits and the propensity to commit driving violations.

1.4 Measures available to reduce the problems of young drivers

Health can be described as the well‐being of individual human beings. By comparison, public health concerns the well‐being of a population (Svanström, 2002), in this thesis specifically the population of young drivers, and it implies that society has to take responsibility for and develop systems to increase the welfare of the population of interest. According to the concept of Vision Zero, if the road users (here young drivers) do not fulfill their responsibility to obey the rules and regulations of the existing traffic system, the responsibility is re‐turned to the designers of the system in that they must make changes and cre‐ate a safer system (Tingvall, 2005). Since society is responsible for the licensing system, which is supposed to produce safe drivers (i.e., drivers that are not killed or severely injured in traffic crashes), a vital aspect of work in the area of public health is to modify the process of licensing in order to improve any situation that is unsatisfactory for young drivers in terms of fatalities and se‐vere injuries. However, as pointed out in sections 1.2 and 1.3, the difficulties surrounding young drivers are multifaceted, which means that a single measure cannot solve the problems. Instead, it will be necessary to employ a combination of different strategies that includes education and training, which are in focus in this thesis, as well as aspects related to policies, laws and regulations and their enforcement, improvements in the road environment, public information, campaigns, safer vehicles, and development of in‐vehicle devices that support

26

Background

drivers. It is also important that the different strategies and measures be used in a mutual effort to solve the problems of young drivers (e.g., Hernetkoski & Keskinen, 2003; OECD, 2006), although driver training is also an important component in this context.

1.5 The potential of driver training to reduce the problems of young drivers

One way of dealing with the problems of young drivers is to achieve primary prevention through driver training. The ultimate goal of such a strategy is to enable novice drivers to make correct decisions and thereby be safe in traffic (i.e., not involved in crashes). In recent years, various licensing systems and new methods of driver education have been adopted that have produced promising results (e.g., Nyberg, 2003; Hatakka et al., 2003; Journal of Safety Research, 2003; OECD, 2006). An example of this is driver training that em‐phasizes the importance of aspects such as individual and social precondi‐tions, and insights regarding the benefits of a driving style that includes large safety margins. Another important issue for driver training is how to compel new drivers to use the safety equipment provided in modern vehicles, and to do so correctly. This aspect is very important, because crashes continue to oc‐cur even though society offers, among other things, good driver training, bet‐ter road design and vehicles, and new technologies, as well as carefully planned and enforced traffic legislation.

1.5.1 The three cornerstones of driver education We can describe education as being based on three cornerstones—its goals, its content/process, and the tests—which should form one harmonized entity (Gregersen & Nyberg, 2002; Henriksson et al., 2004). Applying this to driver training, the goals can be defined as the preconditions of the training; the con‐tent/process entails conditions intended to ensure that the goals can be reached; and the tests are adapted to the goals and the design of the educa‐tional content/process. In a coordinated system, the three cornerstones have to be developed to support each other (Gregersen & Nyberg, 2002). However, such harmonization requires, among other things, the involvement of well‐educated professional driving instructors, lay instructors, and driving examin‐ers that together have the necessary knowledge, competence, and teaching skills to fulfill and cover all aspects of the driver training (Gregersen & Ny‐berg, 2002; OECD, 2006).

27

Background

1.5.2 Goals of driver education The fundaments of driver education comprise clearly formulated objectives in the curriculum and in the contents of the training (Hatakka et al., 2003). It is therefore essential to understand what competences learner drivers need and consequently what they should learn to become safe drivers. The Goals for Driver Education (GDE) matrix (Hatakka et al., 2002) has been used as a framework to define what competences should be considered in the licensing process to ensure that novice drivers are as safe as possible when entering the road traffic system alone. It is important to bear in mind that the GDE matrix describes driving in gen‐eral and thus is not completely suitable when considering the behavior of in‐dividual drivers (Hernetkoski & Keskinen, 2003). As can be seen in Table 1, the matrix comprises a four‐level hierarchy of driver behavior (initially described by Keskinen, 1996) and three main training dimensions that should be in‐cluded in driver education. The following description of the GDE matrix is based on reports by Hatakka et al. (2002), Hernetkoski and Keskinen (2003), Gregersen (2004), and Berg (2006).

28

Background

Table 1. Goals for Driver Education (GDE) matrix (Hatakka et al., 2002)

Essential contents (examples)

Hierarchical level

of behavior

Knowledge and skills

Risk increasing factors

Self-evaluation

Goals for life and skills for living

(general)

Knowledge about / control over how life goals and personal tendencies affect driving behavior

• lifestyle/life situation

• group norms

• motives

• self-control, other characteristics

• personal values

• etc

Risky tendencies

• acceptance of risks

• self-enhancement through driving

• high level of sensation seeking

• complying to social pressure

• use of alcohol/drugs

• values, attitudes towards society

• etc

Self-evaluation/awareness of

• personal skills for impulse control

• risky tendencies

• safety-negative motives

• personal risky habits

• etc

Goals and context of driving

(trip related)

Knowledge and skills concerning

• effects of trip goals on driving

• planning and choosing routes

• evaluation of requested driving time

• effects of social pressure in car

• evaluation of necessity of trip

• etc

Risks connected with:

• driver’s condition (mood, BAC etc)

• purpose of driving

• driving environment (rural/urban)

• social context and company

• extra motives (competing etc)

• etc

Self-evaluation/awareness of

• personal planning skills

• typical goals of driving

• typical risky driving motives

• etc

Mastery of traffic situations


• traffic rules

• observation/selection of signals

• anticipation of course of situations

• speed adjustment

• communication

• driving path

• driving order

• distance to others/safety margins

• etc

Risks caused by

• wrong expectations

• risk-increasing driving style (eg aggressive)

• unsuitable speed adjustment

• vulnerable road-users

• not obeying rules / unpredictable behavior

• information overload

• difficult conditions (darkness etc)

• insufficient automatism/skills

• etc

Self-evaluation / awareness of

• strong and weak points of basic traffic skills

• personal driving style

• personal safety margins

• strong and weak points for hazard situations

• realistic self-evaluation

• etc

Vehicle

maneuvering


• control of direction and position

• tire grip and friction

• vehicle properties

• physical phenomena

• etc

Risks connected with

• insufficient automatism/skills

• unsuitable speed adjustment

• difficult conditions (low friction etc)

• etc

Awareness of

• strong and weak points of basic maneuvering skills

• strong and weak points of skills for hazard situations

• realistic self-evaluation

• etc

The first and lowest hierarchical level, vehicle maneuvering, focuses on the im‐portance of automatizing basic maneuvering skills (e.g., how to start the car,

29

Background

shift gears, steer, accelerate, and brake) in order to become a safe driver. If these types of fundamental skills do not become automatized, it will limit the capacity of the driver to observe and predict the behaviors of other road users. This level also emphasizes that a driver must have knowledge of aspects re‐garding the vehicle itself (including maintenance, tires, and seat belts) and the laws of physical forces and road friction. The second level, mastery of traffic situations, concerns the significance of a driver having the ability to adapt her/his driving behavior in accordance with the changes that constantly occur during driving (i.e., being able to master many different traffic situations). This means that the driver must be able to identify potential hazards and simulta‐neously interact with other road users, which includes predicting the behavior of others in traffic and making one’s own behavior predictable for them, as well as knowing and obeying traffic rules. The third level, goals and context of driving, deals primarily with issues related to decisions about the purpose of a particular episode of driving, as well as why, with whom, where, when, and at what time the driving should be done. This level includes matters such as the following: planning the journey and choosing what route to take; considering whether to use other modes of transport than a car; deciding whether to drive during rush hour or when tired or under the influence of alcohol. The highest and fourth level, goals for life and skills for living, comprises personal objectives, motives, and ambitions in general. This deals with personal skills in handling ordinary situations in life and includes social and individual preconditions such as lifestyle, group norms, gender, social background, and age, all of which have been shown to influence attitudes, motives, and behavior and crash involvement as a driver. The idea behind this hierarchical approach is that both success and failure on the higher levels can affect the demands on the lower levels, even though the process can also occur in reverse, that is, changes at the lower levels may also have an impact on the higher levels. The three training dimensions are described in the columns of the matrix. The first column refers to basic knowledge and skills that a driver needs in order to drive safely under normal traffic conditions. On the lower hierarchical levels, this means that a driver has to know the traffic rules and must have the ability to maneuver the car correctly. On the highest levels, the driver needs knowl‐edge and skills regarding how to plan trips beforehand as well as an under‐standing that social and individual preconditions may very well affect driving behavior. The second column includes risk‐increasing factors and thus concerns

30

Background

aspects that are closely related to those in the first column, although the em‐phasis is on making drivers aware of things that are known to increase or de‐crease the risks they can encounter while driving. On the lower hierarchical levels, this includes risks related to driving with worn‐out tires and speeding. On the higher levels, it considers awareness of the risks of driving connected with aspects such as alcohol, fatigue, and moods, as well as risk‐increasing fea‐tures linked to certain lifestyles. The third column is about self‐evaluation and pays attention to how important it is that drivers are aware of and can realisti‐cally assess their own driving ability, and how it is influenced by their per‐sonal situation. On the lowest hierarchical levels this includes achieving good concordance between what people believe they can master as drivers and their actual driving ability in various situations. On the highest levels, it is neces‐sary to make drivers conscious of things like personal tendencies, so that they can adjust and adapt their driving behavior to avoid possible negative effects of those aspects.

1.5.3 Licensing systems It is apparent that driver training and education have traditionally focused on the issues described in the four cells at the bottom left in the GDE framework shown in Table 1 (e.g., Hatakka et al., 2003; OECD, 2006). However, since it has been shown that the road safety problems of young novice drivers are not mainly related to these competences, but rather to the upper and rightmost corner of the matrix, it is of interest to briefly summarize how society has tried to come to terms with the problems concerning young drivers by applying measures and methods related to the driver licensing process. Many different types of driver licensing systems are in use around the world. Despite dissimilarities, all of the systems have in common that they are based on a certain, albeit widely varying, framework (comprising among other things laws, regulations, administrative processes, a curricula, and test proce‐dures) that states the requirements for obtaining a license to operate a motor vehicle in road traffic. Indeed, even a general discussion and classification of the various licensing systems can be difficult to achieve due to the differences between and unique features of the individual systems. However, one way of accomplishing a broad classification into two categories is to distinguish be‐tween what is usually referred to as traditional and graduated licensing sys‐tems. This is described below based on information published by Nyberg (2003) and the OECD (2006).

31

Background

Traditional licensing systems include only one period of theoretical and prac‐tical training that ends with a written and a driving test. However, in some established (single‐phase) systems, drivers receive full license privileges as soon as they pass the tests, which mean that newly licensed drivers are imme‐diately treated in exactly the same way as more experienced drivers. In other systems, drivers are given a probationary license after passing the tests, and to receive full license privileges they must first drive for a period under some sort of restrictions (e.g., a lower limit for blood alcohol content or being subject to selective or corrective measures such as driver improvement courses if they commit traffic violations). The last general variant of traditional driver licens‐ing is the two‐phase system, which has much in common with the other sys‐tems described here but differs in that even after passing the written and driv‐ing tests and receiving a provisional or probationary license, the license holder is also required to undergo some further training (both theoretical and practi‐cal) before being awarded full license privileges. This second phase does not require that any new tests be passed to attain full licensure. These traditional licensing systems are generally used in European countries, and they vary greatly with regard to the stipulated components of the learning process. For instance, in some cases only professional driving instruction is allowed, whereas in other systems a combination of professional and lay‐instructed practice can be elected. In addition, some include a large number of manda‐tory theoretical and driving lessons, whereas others require very few. Graduated licensing systems typically include three stages that are aimed primarily at ensuring that the driver will gain experience under conditions that are as safe as possible. Therefore, different types of restrictions constitute the most important component of the schemes. First is the learner stage, which ends when the applicant passes a driving test. Only supervised practice is al‐lowed during this period. A minimum number of hours of such practice is of‐ten required, and the learner’s permit must be held for a certain length of time, and in some cases there are certain restrictions (e.g., no passengers allowed in the vehicle or the learner is not permitted to use a cell phone while driving). Next is the intermediate stage, and it entails a period with a provisional license that is valid for a specified length of time during which unsupervised driving is permitted. However, there are various restrictions on the driver, such as no driving at night, a low or zero BAC limit, and restraints regarding the pres‐ence of passengers in the vehicle. If the driver complies with the restrictions, he/she receives full license privileges as soon as the stipulated time period is over, and thus this is the last stage of the graduated licensing system, and no

32

Background

further tests are required for complete licensure. There are many varieties of graduated systems, which are used in the United States, Canada, New Zea‐land, and Australia. Examples of differences are the age at what an applicant is allowed to start practicing, the length of the learner stage, restrictions (regard‐ing both quantity and content), and minimum requirements (e.g., concerning the amount of lay‐instructed driving and age at which a full license can be ob‐tained). All licensing systems include one or several of the following main compo‐nents: professional driving instruction, lay instruction, restrictions, a written and a driving test, and advanced training. Possible effects of professional driv‐ing instruction on the crash risks of novice drivers have been discussed exten‐sively over the years. Notwithstanding, it has been difficult to show any bene‐ficial impact of such tuition, for example, there is little evidence that learners who attend formal courses are involved in fewer crashes when they are later novice drivers (e.g., Christie, 2001; Mayhew & Simpson, 2002; Williams & Fer‐guson, 2004; Elvik & Vaa, 2004). Ker et al. (2005) conducted a systematic re‐view and came to the same conclusion with regard to the value of post‐licensing driver education courses. Moreover, it has been argued that the safety effects provided by professional driving instruction are no greater than those achieved by lay instruction (e.g., Mayhew & Simpson, 1996; Spurkeland, 1997; Ferguson, 2003). However, it is also important to consider the types of professional education that have been evaluated. For instance, investigations of graduated licensing performed in Ontario (Boase & Tasca, 1998) and Nova Scotia (Mayhew et al., 2002) examined the impact of driver education offered to license aspirants as a means of reducing the length of the learner period, and both of those studies showed higher crash rates for those who took advan‐tage of such a time discount. In fact, based on the results of those investiga‐tions, it can be concluded that a single day of professionally provided driver education did not make up for the loss of three (Nova Scotia) or four (Ontario) months of experience gained through lay‐instructed driving. Therefore, it seems that giving learner drivers a time discount for taking a driver education course, and thereby allowing them to obtain a license at an earlier age, is not an advantageous strategy with respect to the safety of new licensees (Simons‐Morton & Ouimet, 2006). Nevertheless, some studies have indicated that driver education does have a positive impact on driver safety. For example, Pannacci and Margue (2000) observed that fatal crashes among novice drivers dropped by an average of

33

Background

34% three years after introduction of the two‐phase system in Luxembourg, as compared to the level seen three years before that system was launched. For all other drivers, the corresponding average decline in fatal crashes was 24%. Also, Carstensen (2002) found that changes implemented in the Danish licens‐ing system (e.g., more focus on defensive driving and hazard perception) led to an estimated decrease in crash involvement of 7–21% among young novice drivers compared to older drivers. These results from Denmark demonstrate that the situation for novice drivers can be improved by altering the content of driver education, but they do not reveal whether professional tuition is better than lay instruction, since the latter is not allowed in Denmark. Lay instruction is often a component of driver licensing systems, and it is in‐cluded as either a mandatory or an optional ingredient to serve as a comple‐ment to or substitute for professional driving instruction. There are two rea‐sons for using this component. First, by allowing lay‐instructed practice it is assumed that learners can get more and necessary experience behind the wheel before being allowed to drive on their own. Secondly, it is believed that this experience is gained under conditions that are safer than the traffic cir‐cumstances to which a novice driver is exposed. Several studies have demon‐strated that lay‐instructed driving has many advantages. For instance, it has been shown that very few crashes occur during such instruction (e.g., Williams et al., 1997; Gregersen & Nyberg, 2002; Mayhew et al., 2003), especially com‐pared to the rate of crash involvement seen during the first period of licensure (e.g., Gregersen & Nyberg, 2002; McKnight & Peck, 2002; Williams, 2003). It has also been reported that drivers who have acquired extensive experience before getting a license have fewer crashes during the first period of licensure than drivers who do not have as much experience (e.g., Maycock & Forsyth, 1997). However, it is obvious from crash statistics that merely gaining experi‐ence is not sufficient to solve the crash problem for newly licensed drivers. Therefore, it seems that lay‐instructed driving is a very good strategy, al‐though its potential has not yet been fully explored. All licensing systems include some kinds of restrictions, for example concern‐ing the minimum age of the learner or lay instructor, the length of time the applicant must hold a learner’s permit, minimum requirements for practicing or number of theory lessons, curfews, and mandatory training or educational elements. Restrictions constitute one (and perhaps the most) important feature of graduated licensing programs, and they have been very successful in lower‐ing crash involvement and severe crashes involving young novice drivers. It

34

Background

seems that night‐time restrictions are most effective in reducing crashes among novice drivers (e.g., Ferguson et al., 1996; Agent et al., 2001; Ulmer et al., 2000; Shope et al., 2001; Begg et al., 2001; Foss et al, 2001; Mayhew et al., 2002; Williams & Preusser, 1997; Begg et al., 2000; Boase & Tasca, 1998; Bou‐chard et al., 2000). A positive influence has also been reported in connection with limits on both BAC (e.g. McCartt et al., 2000; McCartt et al., 2001; Begg et al., 2001; Foss et al., 2001; Boase & Tasca, 1998) and the presence or number of passengers in the vehicle (e.g., Begg et al., 2000; Begg et al., 2001; McKnight & Peck, 2002). The main purpose of written and driving tests is to provide a means of ascer‐taining whether license applicants have acquired the competences that the driving curriculum specifies as necessary for safe driving. In other words, it should be that those who pass the tests have gained the required abilities through practicing and theoretical studies, whereas those who fail have not. There are many things that must be taken into consideration when designing and constructing high‐quality tests, but discussion of those aspects is beyond the scope of this thesis (for an overview of important issues related to test de‐velopment, see Henriksson et al., 2004). Nonetheless, since young novice driv‐ers are clearly overrepresented in crash statistics, it is questionable how well existing tests do discriminate between safe and unsafe drivers (OECD, 2006). Advanced training courses represent the final primary component of many licensing systems. Such instruction involves an educational effort that is in some cases included as a mandatory part of the licensing process, although it is more often given in the form of improvement courses for drivers who have committed traffic offences or as voluntary elements for fully licensed drivers. Traditionally, the aim has been to improve maneuvering skills in critical traffic situations, since this has been considered beneficial for driver safety. However, many studies have shown that courses focused on advanced driving skills that are very seldom used do not lead to improved safety, particularly when con‐sidering young drivers. Indeed, it has, for example, been reported that such instruction results in overestimation of driving ability (e.g., Gregersen, 1996; Nolén & Nyberg, 2001; Nyberg & Nolén, 2002) and a higher rate of crash in‐volvement (e.g., Glad, 1988). Therefore, it is now widely assumed that these types of courses should not focus on improving maneuvering skills in critical or difficult situations, but should instead give drivers the experience and knowledge needed to raise risk awareness and develop anticipatory skills and insights related to aspects such as driving with large safety margins and using

35

Background

the vehicle safety equipment (e.g., Nolén et al., 2002; Katila et al., 2004). These conceptions have also been stressed in the EU projects ADVANCED (2002) and NovEv (Sanders & Keskinen, 2004).

1.5.4 The Swedish system for obtaining a class B driv‐ing license

The papers included in this thesis cover roughly a period starting in 1993 with implementation of the reform allowing 16‐year‐olds to practice driving on public roads in Sweden and continuing up to 2005. The following description is a brief overview of the system for obtaining a class B driving license that was in use (and still is in use today) during the indicated period. However, two changes in the Swedish system were made in 2006. In January 2006, it be‐came mandatory for presumptive lay instructors to take an introductory course together with their learner driver in order to be allowed to teach learn‐ers to drive (VVFS 2005:76). Furthermore, in March 2006, a new national cur‐riculum for a class B driving license was presented, which is based on the GDE matrix (VVFS 2006:21). Since September 1993, individuals in Sweden aspiring to obtain a class B li‐cense to drive a private car (smaller vehicle) have the right to begin behind‐the‐wheel training from the age of 16, and the minimum licensing age is 18. The learners can freely choose whether they want to practice with a lay in‐structor (e.g., a parent) or at a commercial driving school, or they can use a combination of both. The curriculum for a class B license during the study period covered nine dif‐ferent areas, each with many sub‐goals. Five of the areas (vehicle‐related knowledge, traffic regulations, risky situations in traffic, limitation of driver abilities, and special applications and other regulations) were theoretical in nature and were assessed by the written test. The remaining four areas (vehi‐cle‐related knowledge, maneuvering the vehicle, driving in traffic, and driving under special conditions) were practical and were included in the driving test. It was considered imperative that all parts of the driving curriculum be learned during the education process to ensure that new drivers possessed the knowledge, attitudes, and skills needed to fulfill the demands made by society for correct traffic behavior (Jonsson et al., 2003).

36

Background

Considering the study period and today, the only mandatory element of driv‐ing instruction in Sweden is an approximately four‐hour‐long risk awareness training session (often called skid training). It is recommended that this train‐ing be done at the end of the tuition period, not long before taking the driving test. The training of risk awareness is done in specially designed enclosed ar‐eas called skid tracks (also known as skid pans), where low‐friction driving is achieved by manipulating either the driving surface or the vehicle (Nyberg et al., 2004). In the summer of 1999, a new curriculum for the mandatory risk awareness training was introduced that led to a complete change in the educational per‐spective. The new curriculum emphasizes aspects such as risk awareness, fore‐sight, and insight into one’s own limitations. It is also goal oriented so that the training facilities have a greater responsibility to develop appropriate educa‐tional tasks. The previous curriculum and regulations stressed the details and specific demands related to how the teaching was to be done, and they also focused heavily on vehicle maneuvering in critical situations (Engström et al., 2001). Some of the skid tracks also provide insight training in specially designed fa‐cilities called “safety halls.” All learner drivers that do their mandatory risk awareness training at these tracks visit the safety hall to receive additional in‐struction (tuition not stipulated in the risk awareness training curriculum). The extra information is designed to give learners knowledge about the vari‐ous types of safety equipment in motor vehicles (e.g., seat belts), why they should be used, and how to use them in a correct manner. Many of the exer‐cises have been designed to illustrate the physical forces in traffic and to allow each learner to personally experience these forces and discuss them with other learner drivers and the instructor (Nyberg et al., 2004). The existing Swedish system also requires that learners pass the written test before being allowed to take the driving test. From 1990 to 1999, the written test consisted of 40 items, all but one of which were multiple‐choice questions, and the test taker did not know how many of the options were correct. If all the correct responses to an item were not identified, the applicant did not get a point for that item. In 1999, a new written test was introduced which consists of 65 multiple‐choice items, each with only one correct answer. During the driving test, the applicant’s performance is assessed in different traffic situa‐tions with respect to various traffic risks. If the test taker makes one error in

37

Background

any of the areas of competence that are assessed, he/she fails the driving test (Henriksson et al., 2004). There is no limit to the number of times an applicant can take either of the tests and still be approved for licensure. For example, if a candidate fails the written or the driving test, she/he can take it again the next day without performing any additional stipulated or required studying or practicing. Due to the design of the Swedish driver education system, the writ‐ten and behind‐the‐wheel tests are the only means by which the owner of the system, the SRA, can verify that license applicants have actually acquired the competencies specified in the national driving curriculum (Sundström, 2003; Henriksson et al., 2004).

38

Aims

2 AIMS The general aim of the work underlying this thesis was to determine the po‐tential of driver education to reduce road traffic crashes involving young driv‐ers, particularly in Sweden. Hopefully, the results and conclusions presented here can also be used as inputs for making improvements in licensing systems in other countries. Papers I–V describe the individual investigations examin‐ing certain aspects related to the educational process, results of the driving tests, and the outcome of the first period as a novice driver. The specific aims of these studies are described below. Paper I The objective of the study was to examine the relation between two compo‐nents of driver education: the way in which the education is carried out and the outcome of the driving test. An additional goal was to analyze the extent to which the test results are affected by background variables such as age, sex, education, nationality, and place of residence. The study was limited to the drivers 18–24 years of age. Paper II The purpose of this study was to explore whether there are any differences between male and female drivers aged 18–24 years with regard to the follow‐ing (all items concern a class B driver’s license, and all data indicate the year 2005): ‐ how and what they practiced to get a license; ‐ the results of the written and driving tests; ‐ involvement in crashes (including type and associated circumstances)

during the first year of licensure. Paper III The aim of this investigation was to evaluate the reform lowering the age limit for practicing driving in terms of its effects on crashes involving young novice drivers (i.e., crashes per 1,000 license holders and crashes per 10 million km) during their first two years of licensure. Paper IV This study had three objectives. The first was to analyze the road safety prob‐lem in terms of crash involvement (crashes per 1,000 drivers and crashes per 10 million km) while practicing for a private car (class B) license and to com‐

39

Aims

pare the results with the corresponding figures for crashes involving drivers during their first two years of licensure. The second aim was to evaluate the solution of the “experience paradox” associated with the age limit of 16 for driving practice (i.e., gaining experience through supervised practicing) by evaluating the costs in terms of crashes during practicing and the benefits in terms of reduced crash involvement after obtaining a license. The third goal was to determine what types of crashes occurred during learner practicing and to compare the observations with the crash pattern during the first two years of licensed driving. Paper V The aim of this investigation was to evaluate how visiting a safety hall in com‐bination with mandatory risk awareness training affects the knowledge and attitudes of learner drivers with regard to airbags, securing loads, seat belts, sitting posture, speed, and tires.

40

Materials and methods

3 MATERIALS AND METHODS

3.1 Description of the materials and methods The five investigations underlying this thesis varied with respect to the meth‐ods, samples, and study periods that were used. Table 2 presents an overview of the materials and methods described in the five papers.

Table 2. Summary of materials and methods used in the five studies (papers I–V) Study period Design Data source Statistical analy-

sis

Paper I 2004

Matching of ques-tionnaire responses with results of the driving test for indi-vidual subjects

Questionnaires National register data regarding outcome of the driving test

Chi-square test t-test Binary logistic regression

Paper II 2005

Explorative study based on aggregated comparisons of data from different sources

Questionnaires National register data regarding outcome of driving tests, police-reported injury crashes, and license holders

Chi-square test t-test Odds ratio with 95% confidence interval

Paper III 1992–1997 Before–After User–Non-user

Questionnaires National register data regarding police-reported injury crashes and learner permit and license holders

Incidence density ratio with 95% confidence inter-val

Paper IV 1994–2000

An aggregated study of the development from practicing to licensed driving

Questionnaires. National register data regarding police reported injury crashes and learner permit and li-cense holders

Odds ratio and Incidence density ratio with 95% confidence inter-val

Paper V 2003

A randomized con-trolled study Experi-mental and control group, one pre-test and two post-tests

Questionnaires

Chi-square test ANOVA General linear model, repeated measures

3.2 General comments about the materials and methods

Questionnaire data were included in all five studies, but they were used for different purposes. For instance, in two of the investigations (papers I and II),

41


questionnaire responses given by newly licensed drivers constituted a source of information about how the practicing during the learning period had been carried out. This retrospective self‐reported approach has both advantages and disadvantages. One benefit in the present context is that the learning period that was considered in the queries had taken place relatively recently. Another general advantage is that it is possible to gather quite a lot of data at a com‐paratively low cost. However, a major drawback concerns the degree of reli‐ability of the data obtained. This is illustrated by the fact that the questionnaire used in the study reported in paper I included the same items for applicants that had just passed the driving test as for those who had just failed, which might have influenced the subjects’ ability to recall what and how much they had practiced. For example, the applicants who had just failed the test might have felt less motivated to indicate on the questionnaire that they had prac‐ticed extensively, even if that was really the case, since it would have sug‐gested that they had problems learning to drive. It could also have been the other way around, namely, that those who failed might have reported that they had done a much greater amount of practicing than was actually the case in order to convince themselves or the researchers that they should have been approved on the test. Another problem with the retrospective questionnaires in four of the studies (papers I, II, III, and IV) is that it might have been diffi‐cult for the respondents to remember everything correctly when reporting de‐tails about events that had occurred over a more or less long period of time. For instance, in two of those investigations (papers I and II), it was possible that the learning period of interest had lasted for several years, and the same might have applied to items used in the other two studies (papers III and IV) to gain information about the amount of driving done during practice and as novice drivers. It is not easy to control for such biases, but it is important to at least test the suitability of questionnaires before they are distributed, which was in fact done for all of the instruments used in the present investigations. Additional problems related to questionnaires include the size of the dropout rate and not knowing whether there are any particular differences between those who do and those who do not respond. Since no in depth analysis of the non‐respondents was performed in the present studies, it is impossible to con‐clude how the matter of dropouts may have confounded the results. Three of the studies (papers II, III, and IV) also used police‐reported informa‐tion on traffic crashes involving fatalities and injuries. Even though these data were compiled on a national level, there are problems associated with using such information. This is indicated by studies showing difficulties related to

42


dropouts and also regarding poor agreement between filing of traffic injuries in different registers (Thulin, 1987; 1998; Lindqvist, 1991). The latter observa‐tion is illustrated by results reported by Thulin (1998) demonstrating that many traffic injuries are registered by the health services but not by the police, whereas the opposite is true for traffic fatalities. Thulin concluded that the number of police‐reported traffic injuries must be multiplied by a factor of 3.6 to reach the same level as the total number of injuries reported in the statistics by the health services and the police. Moreover, Lindqvist (1991) found that only 23% of the traffic injuries reported by the health services were also re‐ported by the police. Also, it is probable that there is a greater risk that police‐reported data will give an incorrect picture of injury crashes that occur during practice compared to those that take place during licensed driving. One reason for this is that it is the instructor (professional or layperson) that has the legal responsibility for the driving done during practice. Therefore, it is probable that the risk of injury crashes described in paper IV was underestimated to a greater extent for learner drivers than for those driving during the first two years of licensure. It might seem more suitable to use injury data compiled by stakeholders such as insurance companies, although there are problems con‐nected with all types of registers. For example, statistics from insurance com‐panies will be affected by whether the people who are insured actually report their injuries to the companies, which is not certain considering the impact of such events on various bonuses or other benefits associated with their insur‐ance policies. Data such as police‐reported injury crashes have the advantages that they are seldom influenced by the countermeasures that are evaluated, and it can be assumed that the dropout problem will be similar in all groups that are compared (Gregersen, 1995). In light of this discussion, it seems that the levels of crash involvement and crash risks are generally underestimated, although the relative differences between the groups that are compared are probably regarded as reliable. In light of the discussion above, the results reported in the present papers should be interpreted with some caution. This is particularly important when considering the fact that three of the studies (papers II, III, and IV) are based on aggregated comparisons, which means that the same individuals were not followed through all stages of the analysis. Accordingly, the findings of these investigations represent probable patterns and correlations, not definite causal relationships. Therefore, to verify the current interpretations, it will be neces‐sary to perform studies in which the same individuals are investigated

43


through all phases: the learning period, the time of the driving tests, and the first years as novice drivers. It should also be pointed out that certain issues discussed in the present pa‐pers should have been better formulated. For instance, in paper IV it is men‐tioned that a cost‐benefit analysis was carried out. However, that is an over‐statement, because the analysis did not value the effects in monetary terms (Drummond et al., 1997). A more correct (but still not perfect) way of describ‐ing the strategy that was used would be to call it a cost‐effectiveness analysis, since the consequences of driving were measured in “natural units” (crash in‐volvement) without any attempt to give them monetary values (Drummond et al., 1997).

3.3 Practicing in relation to the outcome of the driving license test (paper I)

The study reported in paper I was designed to enable matching of question‐naire responses with the results of the driving test for individual subjects. The questionnaire was administered immediately after license applicants had taken the behind‐the‐wheel test, and the items on the instrument concerned what was included in practicing, and thus they were constructed in accor‐dance with aspects that are assessed on the driving test. The questionnaire was distributed at all 31 of the Swedish driving test centers during a period of approximately three weeks in August–September 2004. Each center received a proportional share of a total of 5,000 copies of the ques‐tionnaire (based on how many class B driving tests they had administered in 2003), and they were instructed to give one to every 18–24‐year‐old applicant immediately after conclusion of the driving test (regardless of whether they passed or failed). Accordingly, it was not possible to send out any reminders. In all, 1,645 license applicants filled out the questionnaire. Of those individu‐als, 1,098 had passed the driving test, and 547 had failed. The data on the results of the driving test originated from the database STAPRO, which, among other things, comprises the following information on individual applicants: sex and age, when the test was taken, the outcome (passed or failed), whether the application was submitted in person or through a driving school, at which center the test was administered.

44


To minimize the problems associated with the dropout rate (only about 33% of the questionnaires were completed correctly and returned by the license appli‐cants), the data from the questionnaires were weighted against data on all 6,225 18–24‐year‐olds who took the driving test during the period the ques‐tionnaire was distributed at the test centers. The variables used in the weight‐ing were age, sex, passed or failed the driving test, and whether application for the test was done through a driving school or privately. This information was obtained from the national register of driving tests (from the database STAPRO). For the questions that concerned background variables, general driver educa‐tion issues, and features of lay‐instructed training and driving school training, the analyses were performed in three steps: 1. Every variable within each category was tested separately using a chi

square statistic or a two‐sample t‐test. The level of significance was set at 0.1%.

2. All variables belonging to each category were tested together to ascertain which of the variables within each category which could best explain the results of the driving test.

3. All variables that were found to successfully predict the outcome of the driving test in the second step were tested together to determine which of the variables included in the survey was the best predictor.

Steps 2 and 3 were tested using a binary logistic regression approach (with 95% confidence interval) and the outcome of the driving test (failed or passed) as the dependent variable.

3.4 Practicing for and performance on driver’s license tests in relation to gender differences in crash in‐volvement among novice drivers (paper II)

The study described in paper II was based on aggregated comparisons of data from different sources, and hence it was not possible to investigate and follow individual drivers through all three stages of driver development. Despite that, the approach used made it possible to explore and discuss any dissimi‐larities between the younger male and female novice drivers during the differ‐ent stages.

45


The data on practicing consisted of responses to a questionnaire, which were obtained from a randomly drawn sample of 1,716 drivers aged 18–24 years who were issued licenses in September 2005. The items concerning what was included in practicing were structured in accordance with aspects that are as‐sessed on the driving test. The questionnaire was distributed in October 2005, and two reminders were sent at two‐week intervals to increase the response rate. The sample was drawn so that there would be a correct proportion of newly licensed drivers in each age group in relation to all licenses issued in 2004. In all, 1,135 newly licensed drivers aged 18–24 years filled out the ques‐tionnaire. Of these individuals, 611 were females and 524 males. The data on the results of the written and driving tests were general in nature and covered all tests taken during the year 2005 by 18–24‐year‐olds. Data regarding all motor vehicle injury crashes (registered by the police) that occurred in 2005 and involved 18–24‐year‐old car drivers who had had a li‐cense for no more than one year were obtained from the national database STRADA. Each crash in that database is classified as one of the following ten conflict types: single crash, oncoming vehicle, overtaking or lane changing, rear‐end, turning at intersection, vehicles on intersecting course, vehicle–bicycle/moped, vehicle–pedestrian, vehicle–animal, and other crashes/unknown. Each crash was also classified according to light conditions, road conditions, weather conditions, time when it occurred, and the most se‐vere outcome. Data from a register compiled by the SRA was used to calculate the size of the group of 18–24‐year‐olds who obtained a driver’s license in 2005 as a basis for risk calculations and as a population from which the questionnaire sample was drawn. The register comprises information on all license holders, includ‐ing their age and sex, and the type of license and date issued. The following analyses were performed:

1. Assessment of differences in how females and males aged 18–24 prac‐ticed to get a driver’s license, based on questionnaire data collected in 2005.

2. Evaluation of gender differences among 18–24‐year‐olds with regard to the outcome of the written and driving tests for a license in 2005, based on national statistics.

3. Comparison of 18–24‐year‐old female and male drivers with respect to distribution of crashes during the first year after being issued a driver’s

46


license; the analysis included the types and circumstances of crashes that occurred in 2005 and was based on national statistics.

4. Calculation of gender differences in health risks (crashes per 1,000 driv‐ers) in 2005 among 18–24‐year‐old drivers during the first year of licen‐sure, based on national statistics.

Items 1–3 were tested using a chi square statistic or an independent samples t‐test, and item 4 was analyzed using the odds ratio with a 95% confidence in‐terval. Adjustments were made to minimize the risk of that significance would be overstated due to the large number of tests. Therefore, the level of signifi‐cance was set at 0.0004 for the questionnaire data and 0.008 for the crash data.

3.5 Sixteen years age limit for learner drivers in Sweden—an evaluation of safety effects (paper III)

In 1993, Sweden implemented a reform to allow learner drivers to start prac‐ticing behind the wheel from the age of 16 years, and this was done on a na‐tional level, which made it impossible to evaluate the change by use of an ex‐perimental design. Therefore, two designs were combined (a before–after method and a user–non‐user approach) to minimize the problems associated with the separate strategies. The before–after design cannot differentiate the effects of the 16‐year age limit reform from other time‐related modifications, such as economic changes in society, unemployment, or fluctuations in weather conditions. The design comparing users and non‐users includes a self‐selection bias with regard to aspects such as greater interest or resources among the users. Three different groups were delimited and compared in the present study (paper III). The new group of younger drivers was designated the 16‐year‐olds, because it included those who took advantage of the possibility to start prac‐ticing as learners from the age of 16 years. The two control groups were as fol‐lows: the pre‐reform 17½‐year‐olds, which comprised learners who obtained a driver’s license before the reform (i.e., the change) was implemented; and the post‐reform 17½‐year‐olds, which included individuals who did not utilize the new possibility of beginning behind‐the‐wheel driving practice from 16 years of age, but instead started practicing after reaching the age of 17½. Common for all groups was the age limit of 18 years for obtaining a license.

47


To control for the trends over time and thereby avoid some of the problems in the before–after comparison, an analysis was performed to determine the crash involvement trend among young drivers from 1992 to 1997, which was the period covered in the effect evaluation. In addition to the trend analysis, two other possible confounding factors were estimated and controlled for: socio‐economic background differences and age at which the drivers passed their license tests. Responses to the questionnaire item ”What is the highest level of education among members of your family?” were used as an indicator of socio‐economic background. More exact information on this factor was not available to accomplish the analysis of crash involvement, and thus a broader interpretation of such data was done in order to avoid overestimation of the effect of the change in the age limit. In this case, it was further assumed that the crash involvement may also have been influenced by the age at which the drivers obtained a license. More specifically, if those who took advantage of the 16‐year age limit for behind‐the‐wheel practicing received a license at a younger age than did those in the control groups, their crash involvement may have been due in part to their earlier exposure to traffic. Such an impact would also have been a result of the changed age limit, and hence these effects were also corrected for. The crash data were collected from the police register of such incidents. Only crashes leading to fatalities or personal injuries were included, and, for each one, information was derived regarding the driver and the type and date of the crash. Data concerning the dates when learner’s permits and licenses were issued were obtained from the national license register. The first criterion used to assign drivers to the three comparison groups was that the license was to have been obtained at the age of 18 years, not 19 or older. The second criterion was that the selected drivers were to have had a license for more than two years, since the aim was to investigate the effect of the change during the two first years of licensure. In all, these analyses came to include 243,823 drivers and 4,192 police‐reported crashes. The samples selected for the additional trend analysis consisted of young drivers between 20 and 24 years of age. Also, a questionnaire was used to ac‐quire information about various issues, and the individuals chosen to give re‐sponses to that instrument were randomly drawn from the Swedish national license register. The questionnaire was sent at different times to drivers in the three comparison groups who had had a license for two years. Only responses

48


regarding driving mileage and socio‐economic background were used in this study (paper III). The analysis was conducted as follows: 1 The three comparison groups were identified in the two population regis‐

ters by considering individuals who met inclusion criteria, which indicated both the total number of drivers in each group and the number in each group who had been involved in police‐reported crashes with personal inju‐ries.

2 Data on age and date when a learner’s permit and license were obtained were transferred from the license register to the corresponding post in the crash register. Social security numbers were used to find data on the same individuals in the two registers.

3 Crashes per 1,000 license holders in each comparison group were calculated. 4 Questionnaire responses regarding mileage driven in each group were used

as estimates of exposure when calculating risk based on the population reg‐ister data.

5 Crash risk (crashes per 10 million km) was calculated for each of the three comparison groups.

6 The general effect of the reform was analyzed by combining the 16‐year‐old drivers and post‐reform 17½‐year‐old drivers and comparing their crash in‐volvement with the pre‐reform 17½‐year‐old drivers.

7 An inter‐group comparison was conducted regarding crash involvement of the 16‐year‐old drivers, the post‐reform 17½‐year‐old drivers, and the pre‐reform 17½‐year‐old drivers.

8 Confounding factors were estimated based on questionnaire data concern‐ing socio‐economic background, trends in national crash statistics, and na‐tional register data on differences in licensing age.

Differences in crash risk were tested using the incidence density ratio with 95% confidence intervals.

3.6 Accident involvement among learner drivers—an analysis of the consequences of supervised practice (paper IV)

At the time the study described in paper IV was undertaken, police‐reported crashes were registered in a computerized database called OLY/VITS, which included crashes that could be identified as having taken place during driving practice. Information from the OLY/VITS database was used to analyze crash

49


involvement during driving practice and during the first two years after ob‐taining a license. All police‐reported injury crashes involving private cars (i.e., a class B license) were used in the analyses. No crashes among drivers lacking a learner’s permit or supervision were included. The analysis of conflict types was based on the classification of the crashes that was used in the crash data‐base, and only one conflict type was used for each crash. The following 10 con‐flict classifications were used: no conflict (single‐vehicle crash), oncoming ve‐hicle, overtaking or lane change, rear end, turning at intersection, vehicles on intersecting course, reversing or turning around, parking, vehicle–animal, and unknown. The main analyses included data covering 1 January 1994 to 31 De‐cember 1996, and the period was extended to 31 December 2000 in some of the assessments. In Sweden, all license holders are included in a national driving license regis‐ter at the SRA. These records comprise information on individual licensees with regard to, among other things, the dates on which a learner’s permit, a lay instructor’s permit, and full licensure were issued, as well as the type of license and facts about the lay instructor. Information from this license register was used to calculate the size of populations of different groups of learner drivers and license holders during the period 1994–1996. In the evaluation of the 16‐year age limit for driving practice (paper III), a se‐ries of questionnaire surveys was conducted to acquire information about the amount of behind‐the‐wheel practicing that had been done during the learner period by randomly selected newly licensed drivers. Two groups of drivers, having licensure for one and two years, respectively, were also asked about their annual driving exposure as licensees. These data were used as estimates of exposure in the calculation of crash risk before and after licensing. Exposure data were collected for the period 1994–1996 for learner drivers who were 16–17 years of age and novice licensed drivers who were 18–19 years old. The cost‐benefit analysis (or cost‐effectiveness assessment, as discussed in sec‐tion 3.1) was carried out by making use of the results from the evaluation of the 16‐year age limit reform described in paper III. The costs were defined as the number of crashes per 1,000 learner drivers aged 16–17 years. The benefits were defined as the reduction in crashes during the first two years of licensed driving that the evaluation study (paper III) had discerned for those who util‐ized the possibility of starting behind‐the‐wheel practicing at a younger age.

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For the youngest drivers, crash risks during practice and after licensing were compared only for the period 1994–1996, because exposure data were not available for 1997–2000. The crash risk during driving practice included 16–17‐year‐old learners, and the risk after licensing comprised 18–19‐year‐old li‐censed drivers. Even if the study did not systematically follow the same indi‐viduals from learner to licensure, the idea of the age selection was to achieve an aggregated analysis of the development from practice to licensed driving. The extended period 1994–2000 was covered in the evaluations that did not consider the population size or exposure data. The following analyses and comparisons were carried out: 1. Calculation of health risk (crashes per 1,000 drivers) among 16–17‐year‐old

learner drivers and 18–19‐year‐old novice drivers in 1994–1996. 2. Calculation of crash risk (crashes per 10 million km) among 16–17‐year‐old

learner drivers and 18–19‐year‐old novice drivers for the period 1994–1996. 3. Cost‐effectiveness analysis in terms of crashes occurring during practice

versus reduction of crashes involving novice drivers. 4. Analysis of conflict types in crashes involving either 16–17‐year‐old learner

drivers or 18–19‐year‐old novice drivers in 1994–2000. 5. Comparison of the distribution of crashes and crash types occurring during

lay‐instructed and professionally supervised training performed by learner drivers of all ages in 1994–2000.

Differences in health risk (crashes per license holder population) and crash risk (crashes per kilometers) were tested using the odds ratio and the inci‐dence density ratio with a 95% confidence interval.

3.7 Safety halls—an evaluation (paper V) All learner drivers that completed their mandatory risk awareness training at the eight skid tracks with safety halls during the investigated period (two weeks in May 2003) were included in the study reported in paper V. No par‐ticular exclusion criteria (e.g., regarding age, gender, or whether learning at a driving school or being taught by layperson) were used to restrict participa‐tion, with only two exceptions: learner drivers were not included if they needed an interpreter and/or if they had failed the risk awareness training on an earlier occasion. The included learners were randomly assigned to an ex‐perimental or a control group on the basis of what day they had participated in training at the skid track; the safety halls had been closed on the days that

51


the drivers assigned to the control group had done their skid training. The learner drivers included in the control group were given the opportunity to visit a safety hall free of charge six months later, if they so desired. At each of the eight skid tracks, data were collected on 125 learner drivers assigned to the experimental group and 125 assigned to the control group, thus information on a total of 1,000 learners in each group was gathered for subsequent analy‐sis. Both groups completed the mandatory risk awareness training, whereas only members of the experimental group visited a safety hall. Each of the learner drivers that took part in the study filled out a questionnaire on three different occasions.

1. Pretest: administered as soon as the learners arrived at the skid track. 2. Posttest 1: administered directly after they had finished their training. 3. Posttest 2: administered about 18 weeks after the risk awareness train‐

ing; the questionnaire was sent by mail to the same participants that had completed the first two questionnaires.

Essentially the same questionnaire was used on all three testing occasions, and it covered two main areas:

1. Knowledge about airbags, securing loads, seat belts, sitting posture, speed, and tires. There were eleven questions, which had three to seven response options (including “I don’t know”). For all but one of the items, only one answer was correct.

2. Attitude towards 28 different statements about airbags, securing loads, seat belts, sitting posture, speed, and tires. The learners were to mark a response by drawing a circle around a number on a scale from 1 to 7, where 1 stood for “agree completely” and 7 meant “disagree com‐pletely.”

Inasmuch as the pretest and posttest 1 were administered at the skid tracks, the amount of time available for filling in responses was limited. Accordingly, items about background factors could be included only on posttest 2, which also comprised questions about how the learner drivers in the experimental group had experienced their visit to a safety hall. The response rate varied, and the dropout rate was highest for posttest 2. A total of 1,326 learner drivers (658 in the experimental group and 668 in the con‐

52


trol group) completed all three questionnaires, and the analysis was per‐formed on the responses provided by those participants. An additional evaluation was conducted to discern any dissimilarities be‐tween those who did and those who did not answer the final questionnaire. This was done by comparing the responses to the pretest and posttest 1 given by the 1,326 persons that answered all three questionnaires and by all 1,979 participants. We did not find any apparent differences between these two groups, which indicates that there were no particular disparities between those who did and those who did not complete posttest 2. Data analysis in the study was done using chi‐square statistics, one‐way ANOVA, or general linear model (GLM) repeated measures. Chi‐square statis‐tics and one‐way ANOVA were used to ascertain whether differences existed between the experimental and the control group before any training took place (i.e., at the pretest). Also, chi‐square statistics were applied to analyze the re‐sponses to each knowledge question. A knowledge index was calculated by counting the number of correct answers given by each of the participating learners. The scale used in the items about attitudes gave a high value (7) for a positive response (i.e., a safe attitude) and a low value (1) for a negative re‐sponse (i.e., an unsafe attitude). An index was calculated for each of the topics that were considered (airbag, securing loads, seat belts, sitting posture, speed, and tires). The items included in the six different indexes were decided in ad‐vance, since the aim of the study was to evaluate the effects of the information taught in the halls separately for each topic. GLM repeated measures was also used to analyze the indexes for knowledge questions and attitudes, respec‐tively. A mixed model have been used were one of the studies two independ‐ent variables was treated as a between‐group variable (group) and the other was treated as a within‐group variable (measuring occasion). A significant in‐teraction between these two independent variables indicates that the learners in the experiment group have changed more or less than the learners in the control group, which in turn implies that the education in the safety hall had had an effect. Age and gender were entered as covariates in the analyses to control for possible confounding influence of these two variables as well. In all cases, the level of significance was set at 1%.

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54

Results

4 RESULTS

4.1 Practicing in relation to the outcome of the driving license test (paper I)

The study reported in paper I showed no gender‐related difference (consider‐ing total data) in the results of the driving test. Furthermore, the same was true even after data on both sexes were divided up according to age at the time the test was taken, and also after taking into account the age at which behind‐the‐wheel practicing was begun. In addition, it was found that males and females had practiced driving for the same amount of time before taking the test (on average 73 hours). The logistic regression model of the relationship between background vari‐ables and the outcome of the driving test showed that age when taking the test, parents’ education, and parents’ country/countries of birth were the three most important variables to take into consideration when trying to explain the test results. Regarding general driver education features and the outcome of the driving test, it was found that the total amount of time spent studying and training did not differ between the license applicants who passed the driving test and those who failed when analyzing these variables separately. Moreover, the logistic regression model of the relationship between general features of the education and the driving test results showed a higher probability of passing the test for learners with the following characteristics: started behind‐the‐wheel practice at the age of 16, applied to take the test via a driving school, made use of edu‐cational software at a driving school, and cooperated successfully with the driving instructor. However, the model also demonstrated that the more hours of practicing at a driving school that a candidate needed, the less likely it was that she/he would pass the driving test. In most cases, the results obtained with this logistic regression model confirmed the findings acquired when ana‐lyzing all the variables within this category separately. Further investigation considered the fact that the driving test was passed by more of the learners who applied to take the driving test via a driving school than by those who applied in person. When the data were divided up accord‐ing to how the learners had actually chosen to take tuition, it was found that

55

Results

85% had performed combined training (i.e., they had practiced with both a lay instructor and a driving school teacher), 9% had practiced only with a lay in‐structor, and 6% had practiced solely with an instructor at a driving school. Analysis of the material according to this grouping showed that the learners who chose combined tuition did better on the test (69% passed) than those who practiced only with either a driving school instructor (60% passed) or a lay instructor (46% passed). The logistic regression model analyzing the association between features of lay‐instructed training and the outcome of the driving test revealed that the license applicants had a greater chance of passing the driving test if they had devoted more of their lay‐instructed practicing to backing, speed adaptation, and driving on narrow and curvy roads, and also if they had done much of the training in dry weather. On the other hand, the likelihood of passing the driv‐ing test was lower for learners that spent a larger proportion of their lay‐instructed driving by practicing on hard braking, overtaking, driving through areas of road work, and trying to handle the task of adjusting following dis‐tance. The logistic regression model of the relationships between aspects of driving school training and the outcome of the driving test showed that the probability of passing the driving test was greater for applicants who had done a larger proportion of the driving school practicing in daylight, in dry weather, per‐forming a safety check, parking, entering a wide 70 or 90 km/h road, and try‐ing to adjust driving speed according to the existing circumstances. On the other hand, the chances of passing the test were lower for learners who de‐voted more of their driving school training to practicing on wet roads, shifting gears, making right turns, and overtaking other vehicles on 70 or 90 km/h roads.

56

Results

Table 3. Full model explaining the outcome of the driving testa

Estimated OR 95% CI Variables (Exp (B)) for Exp (B) Age when starting behind-the-wheel training

16 1.0017 0.80 (0.59-1.09)18 0.67 (0.47-0.96)19 0.55 (0.34-0.91)20 0.56 (0.32-0.97)21- 0.53 (0.32-0.87)No information 0.67 (0.17-2.59)

Applied to take the driving testIn person 1.00Via a traffic school 2.73 (2.07-3.61)

Total hours behind-the-wheel instruction at driving school 0.98 (0.96-0.99)

Use of educational software at driving schoolNo 1.00Yes 1.36 (1.06-1.75)

Other educational aids than those specified in surveyNo 1.00Yes 1.88 (1.16-3.04)

Cooperation with driving school teacherVery good 1.00Fairly good 0.44 (0.34-0.58)Neither good nor poor 0.46 (0.29-0.73)Fairly poor 0.46 (0.25-0.86)Very poor 0.31 (0.19-0.50)

Dry weather (during lay-instructed training) 1.05 (1.01-1.10)Narrow curvy roads (during lay-instructed training) 1.09 (1.04-1.14)Speed adaptation (during lay-instructed training) 1.06 (1.01-1.11)Following distance (during lay-instructed training) 0.88 (0.84-0.93)

Wet road conditions (during driving school training) 0.92 (0.87-0.98)Parking (during driving school training) 1.06 (1.01-1.12)Right turns (during driving school training) 0.89 (0.85-0.94)Speed adaptation (during driving school training) 1.06 (1.01-1.12) Estimated odds ratio (Exp (B)) and 95% CI for Exp (B). aDependent variable encoding: failed = 0; passed = 1. The forward stepwise (likelihood ratio) method was used. The model was based on the variables found to be of significance in four earlier logistic regression analyses. The final logistic regression model described in paper I was based on all vari‐ables found to be of significance for the outcome of the driving test in the four previous logistic regression analyses. When all these variables were consid‐ered (Table 3), none of the background variables proved to be statistically sig‐

57

Results

nificant in attempts to explain the results of the driving test. However, general driver education variables appeared to be among the most important. Table 3 also shows that, of all the features of lay‐instructed training, only driving in dry weather and on curvy and narrow roads, and practicing speed adaptation and following distance seemed to have a substantial impact in evaluations of the outcome of the driving test. The likelihood of passing was greater when a greater proportion of the lay‐instructed driving practicing was devoted to the first three of the mentioned tasks, whereas the risk of failing was higher for those who spent more time learning to manage following distance. The data in Table 3 also suggest that four of the driving school training variables influ‐enced the results of the driving test: the probability of passing was greater if a larger proportion of the driving school‐supervised practicing was used to learn parking and speed adaptation, whereas the chance of passing was lower if more of the training was focused on making right turns and driving on wet roads. Overall, this final logistic regression model classified 72.17% of the sample cor‐rectly, although the rate of successful classification was greater for those who passed the driving test than for those failed (86.98% and 42.43% correctly clas‐sified, respectively).

4.2 Practicing for and performance on driver’s li‐cense tests in relation to gender differences in crash involvement among novice drivers (pa‐per II)

The analyses of dissimilarities between females and males aged 18–24 regard‐ing how they practiced to get a driver’s license showed no significant gender differences in the background variables age, occupation, own education, par‐ents’ education, place of residence, and parents’ country of birth. More females (81%) than males (69%) had applied to take the driving test via a driving school, and, conversely, more of the males had applied on their own (p < 0.0004). Nevertheless, the route of application does not reveal anything about how these individuals actually practiced, since 93% of the females and 87% of the males had combined lay instruction with practicing at a driving school. Apparently, a larger proportion of the males (7%) than the females (2%) had practiced only with a lay instructor (p < 0.0004). No gender differences were found in the total amount of practicing (i.e., the number of hours of both lay

58

Results

and driving school instruction). The average total time spent practicing was approximately 54 hours. It is worth noting that only 4% of both sexes had used the official national curriculum to understand the goals of the driver educa‐tion. However, in all, the females spent more time studying for the written test than the males did, and this applies to learning at home (24.6 hours vs. 18.8 hours, p < 0.0004), and classroom lessons at a driving school (6.5 hours vs. 4.7 hours, p < 0.0004). On the other hand, there was no gender difference with re‐spect to the number of times the subjects took the written or the driving test before they passed (mean approx. 1.4 times). It is also notable that 31% of the females and 41% of the males chose not to take any classroom lessons at a driving school. There were no significant gender differences in the total number of hours of lay‐instructed driving (average approx. 44 h). On a five‐level response scale, almost 93% of both female and male learners indicated that their cooperation with lay instructors had been “fairly good” or “very good.” However, only about 10% of the learners reported getting “quite a lot” or “very much” sup‐port and/or advice from a driving school about how to structure their lay‐instructed practicing (also on a five‐level response scale). Lay‐instructed driv‐ing occasions that were performed according to a plan and with the sole pur‐pose of practicing were on average more common (p < 0.0004) among the fe‐male learners (44%) than among the males (36%). On average the female subjects performed lay‐instructed driving more often (p < 0.0004) in daylight, on dry roads, and in dry weather, whereas such training by male learners was generally done more frequently (p < 0.0004) under slip‐pery road conditions. In addition, compared to the males, the female learners to a greater extent (p < 0.0004) practiced many different types of driving skills during lay instruction, including both clearly‐defined tasks (e.g., parking, backing, shifting gears/starting/stopping, and driving through pedestrian or bicycle crossings, intersections, and roundabouts) and more comprehensive exercises (e.g., speed adaptation, following distance, visual searches, and pay‐ing attention to vulnerable road users and dangerous situations). The male learners did not practice any skills more than the female learners did. The female learners had practiced driving a significantly (p < 0.0004) larger number of hours under supervision of a qualified instructor than their male counterparts did (14.9 and 10.4 hours, respectively). Behind‐the‐wheel training at a driving school was most often done at the end of the practicing period,

59

Results

and no gender difference was found in this aspect. Also, almost 90% of both female and male learners classified cooperation with their driving instructor as “fairly good” or “very good.” On average female learners devoted a larger proportion (p < 0.0004) of their training at a driving school to practicing in traf‐fic environments (such as urban roads) and under favorable driving condi‐tions (such as in daylight and in good weather), as well as in heavy traffic. As was the case for lay instruction, females were generally inclined to practice many different types of maneuvers during lessons at driving schools, and the exercises that they invariably performed more than males (p < 0.0004) in‐cluded both clearly‐defined tasks (e.g., backing and driving through pedes‐trian or bicycle crossings and intersections) and more comprehensive exercises (e.g., speed adaptation and scanning for vulnerable road users and dangerous situations). None of the skills were practiced more by males than by females. When asked to compare themselves with the average driver, young male nov‐ice drivers generally assessed (p < 0.0004) their own driving ability on a higher level than their female counterparts did in relation to nine of the eleven driv‐ing skills considered in the questionnaire items. National statistics showed that the outcome of the written test among 18–24‐year‐olds in 2005 was better for females than males (test passed by 58% and 50%, respectively). Furthermore, the proportion of 18–24‐year‐olds who passed the driving test in 2005 was approximately the same for both sexes (64% and 63%, respectively). In 2005, a total of 868 police‐reported injury crashes were registered in Sweden for 18–24‐year‐olds during their first year of licensed driving, and 275 (31.7%) of those crashes involved females and 593 (68.3%) males. About 18% of the crashes that year led to fatalities or severe injuries. The mean health risk (i.e., number of crashes per 1,000 drivers) during the first year of licensed driving in this age group was 7.04 for females and 13.62 for males. Calculating odds ratio values demonstrated that, for the age group and year under consideration, the probability of being involved in a police‐reported injury crash during the first year of licensed driving was on average 1.94 times higher for male than for female drivers (CI 1.69–2.26, p < 0.05). All crash conflict types (total numbers) in the age group 18–24 years in 2005 were more common among male than female drivers, but no significant gender differences in relative distribution were found when considering the ten conflict types separately. For both sexes, single‐vehicle crashes were most frequent, followed by rear‐end crashes and collisions with other vehicles on an intersecting course. Nevertheless, signifi‐

60

Results

cant gender differences were observed when considering other circumstances associated with the crashes. The data at hand suggest that a larger proportion of the crashes involving the female drivers occurred in daylight and between 5 a.m. and 4 p.m.; by comparison, more of the crashes assigned to the male driv‐ers took place in darkness and between 5 p.m. and 4 a.m.

4.3 Sixteen years age limit for learner drivers in Sweden—an evaluation of safety effects (paper III)

Comparison of the pre‐reform 17½‐year‐old learner drivers with the other two groups of learners combined (i.e., the post‐reform 16‐ and 17½‐year‐olds) with respect to their involvement in road crashes gave a measure of the general ef‐fect of the new rule lowering the age limit for behind‐the‐wheel practice to 16 years. This analysis showed that, compared to pre‐reform levels, after the re‐form there was a 20.8% reduction in the rate of crashes per 1,000 drivers and a 17.2% decrease in crashes per 10 million km driven (Table 4). Analyses of the monthly development of crashes per 1,000 license holders re‐vealed that the 16‐year‐olds had a lower rate of crash involvement than the controls over a two‐year period, and that difference was still pronounced even after that time. Considering gender differences, the rate of crashes per 10 mil‐lion km was lowered among both sexes after the reform, although the reduc‐tion was greatest for females.

The effects of three additional possible confounding factors (socio‐economic background, general crash trend, and licensing age) were also evaluated, and it was found that a higher percentage of the individuals in the 16‐year‐old group belonged to families that included members with a university educa‐tion, as compared to the other two groups. Making an extremely broad and speculative assumption that there were indeed no crashes at all involving the overrepresented share of drivers from families with a higher education, the crash involvement of the 16‐year‐olds would be reduced by 7.8% compared to the pre‐reform 17½‐year‐olds and by 21.9% compared to the post‐reform 17½‐year‐olds. Furthermore, trend analysis of crash involvement among 20–24‐year‐old drivers during the study period indicated a crash reduction of 2.5%. Regarding licensing age, it was found that the 16‐year‐olds and the pre‐reform 17½‐year‐olds obtained a license approximately one month earlier than the

61

Results

post‐reform 17½‐year‐olds. Considering the post‐reform 17½‐year‐olds drivers and compensating for the observation that they had one month less exposure (which represents about 4.2% of a period of 24 months), along with the esti‐mated influence of the other two confounding factors, it seems that the total effect of the extended learning period (i.e., for the 16‐year‐olds and the post‐reform 17½‐year‐olds together) was an approximately 15% reduction in the rate of crashes per 10 million km among novice 18–19‐year‐old drivers (Table 4). Table 4. Differences in crashes per 1,000 drivers and crashes per 10 million km driven be‐tween the 16‐year‐old group and the two control groups with and without controlling for confounding factors

16 - 17½ Pre –48.2% –45.9% –42.3% –39.8%16 - 17½ Post –45.5% –45.8% –27.1% –23.9%16 + 17½ Post - 17½ Pre –20.8% –17.2% –18.7% –15.1%

16 = the 16-year-olds17½ Post = the post-reform 17½-year-olds17½ Pre = the pre-reform 17½-year-olds

Differences according to national register data

Differences after controlling for confounders

Crashes per 1,000 drivers

Crashes per 10 million km

Crashes per 1,000 drivers

Crashes per 10 million km

Compared groups:

As shown in Table 4, it was also found that those who did take advantage of the 16‐year age limit had an approximately 46% lower risk of a crash per driven kilometer than those who learned to drive before the age limit was changed, and the rate was approximately the same compared with the other control group (i.e., those who waited until the age of 17½ to begin practicing, despite the reform). After controlling for the above‐mentioned confounders, the difference in crash risk was still about 40% between the pre‐reform 17½‐year‐olds and the 16‐year‐olds, whereas it decreased to approximately 24% between the 16‐year‐olds and post‐reform 17½‐year‐olds. The marked de‐crease from 45.8% to 23.9% for the 16‐year‐olds compared to the post‐reform 17½‐year‐olds can be explained primarily by the high level of 21.9% estimated for the difference in socio‐economic backgrounds between these two groups.

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Results

4.4 Accident involvement among learner drivers—an analysis of the consequences of supervised practice (paper IV)

Considering all learner drivers during the period 1994–2000, there were 444 police‐reported injury crashes involving 22 fatalities, and, in 123 of those crashes, the learners were 16–17 years old. During the period 1994–1996, which was used in the risk calculations, 63 crashes were reported for this younger group of learners. In 1994–2000, the police‐reported crash rates for novice drivers (< 2 years as license holders) of all ages and of the ages 18–19 years were 13,657 (382 killed) and 5,563, respectively. Also, from 1994 to 1996, the 18–19‐year‐old group of licensed drivers had 2,461 crashes. Data from the national license register indicated that 229,000 learner drivers had started to practice from the age of 16 in 1994–1996, and the population of newly licensed drivers aged 18–19 during the same period was 269,000. For the period 1994–1996, 18–19‐year old drivers during their first two years of licensure were compared with practicing 16–17‐year old learner drivers with respect to the risk of crashes per 1,000 drivers and per 10 million km driven. These analyses showed that the probability of a driver being involved in a road crash after obtaining a license was 33.3 (CI 25.9–42.7, p < 0.05) times higher than the probability of being involved in such a crash while practicing driving. However, since the exposure was more than three times higher dur‐ing the two years after licensing (19,180 km) than under the two years of prac‐ticing (5,880 km), the difference in crash risk per km driven was actually lower than that level; more precisely, the risk was instead 10.2 (CI 7.9–13.1, p < 0.05) times higher during licensed driving. In order to perform the analyses in terms of practice crashes versus reduction of novice driver crashes, the results from the previously published evaluation of the reduced age limit for driving practice to 16 years of age (paper III) have been used. The results showed that the number of police‐reported injury crashes per 1,000 18–19‐year‐old drivers during their first two years of licensed driving was reduced from 19.55 before the reform to 10.13 after the reform for those who had taken advantage of practicing at a younger age. Thus the bene‐fit of the increased possibilities of supervised practice, and thereby increased experience behind the wheel, can be seen as 9.42 fewer injury crashes per 1,000 drivers. After having compensated for the calculated effects of confounding factors (differences in socio‐economic background, general crash trend during

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the study period, and average licensing age), the reduction was estimated to 8.27 injury crashes per 1,000 drivers. Using data from the present study (paper IV), the number of crashes involving learner drivers was calculated to indicate the costs of the supervised training among the 16–17‐year‐olds. In all, the 229,000 learner drivers were involved in 63 crashes, which is 0.275 per 1,000 drivers. Consequently, with regard to crashes per 1,000 drivers, the benefit was 30.1 times higher than the costs (8.27 compared to 0.275). For the period 1994–2000, analysis of road crashes involving 16–17‐year‐old learner drivers compared to crashes involving 18–19‐year‐olds during their two first years of licensure in relation to various conflict types showed that all types of conflicts were much more common after obtaining a license. For this reason, a relative comparison was performed, which revealed that single‐vehicle crashes and conflicts with vehicles on an intersecting course occurred most frequently among novice licensed drivers, whereas intersecting course crashes and collisions with oncoming vehicles when turning at intersections were most common among the learner drivers. Collisions with oncoming ve‐hicles, overtaking, rear‐end and turning conflicts were also relatively overrep‐resented among the learner drivers. All age groups of learner drivers and the entire period 1994–2000 were consid‐ered in a comparison of crash involvement during professional and lay in‐struction. The results indicated fewer crashes (14%) associated with profes‐sional training than with lay‐instructed training (86%). The same pattern ap‐plies to severity of the crashes, in that no fatal crashes occurred during profes‐sional instruction, but 22 persons were killed in 16 fatal crashes during lay in‐struction. The same difference in severity between the two groups was de‐tected concerning distribution of the most severe injuries in each crash and the number of persons injured or killed in those crashes.

4.5 Safety halls—an evaluation (paper V) Before the mandatory risk awareness training took place, there was substantial agreement between the control group and the experimental group, because at that time there were significant differences in only two variables: the number of classroom lessons that had already been taken at a driving school, and whether they had visited a safety hall prior to the risk awareness training. The discrepancy in time spent on classroom instruction was so small (less than one hour) that we deemed it to be irrelevant for interpretation of the results. How‐

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ever, all subsequent analyses were done both with and without inclusion of the data on learners that had visited a safety hall prior to the risk awareness training, and the findings did not differ from any of the results based on all the participants that were included in the final analyses (n = 1,326 learners). In the analysis of the questionnaire results, the responses to the 11 separate knowledge questions revealed no significant differences between the two groups at the time of the pretest. However, on posttest 1, answers to six of the 11 questions indicated a significantly greater improvement in knowledge in the experimental group compared to the control group, and this development was still apparent in the results of posttest 2. It is also clear that the level of knowledge about different questions varied, even when considering the items for which the experimental group had significantly better results than the con‐trol group. For example, on posttest 2, the level of knowledge was high for the item “Mark the picture that you believe shows the correct way to wear a seat belt” (82.4% answered correctly), moderate for the question “Which of the fol‐lowing adjustments can you make yourself to minimize the risk of a neck in‐jury if you are hit from behind while driving” (58.6% answered correctly), and extremely low for the query “What notation shows that a tire was manufac‐tured in December 1999” (only 5.1% answered correctly). Moreover, it was found that almost all participants in the study (more than 95%) already knew the answers to some of the items (e.g., the question “Is there a law stating that all persons traveling in a car must wear a seat belt”) before they did their risk awareness training. Analyses of the total knowledge index revealed no signifi‐cant differences between the experimental and the control group regarding their results on the pretest (for the 11 items on the questionnaire, the mean numbers of correct answers were 5.78 and 5.74, respectively). Both groups showed increased knowledge at posttest 1 (mean numbers of correct answers 7.34 and 6.09, respectively), but the improvement was significantly greater in the experimental group than in the control group (p < 0.01). At posttest 2, the level of knowledge had decreased in both groups (means 6.38 and 5.89, respec‐tively), although the results for the experimental group were still significantly better (p < 0.01). No effect of age and gender were found in these analyses. The pretest indicated no significant differences between the groups with re‐gard to any of the indexes for the attitudes of the respondents towards the various topics taught in the safety halls. However, posttest 1 revealed a sig‐nificantly greater change (p < 0.01) towards safer attitudes among the learners in the experimental group compared to those in the control group when con‐

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Results

sidering all areas of interest except airbags. Posttest 2 indicated the same ten‐dency as observed regarding the knowledge questions, that is, that, for both groups, the results were better on posttest 1 than on posttest 2. Nevertheless, the learners in the experimental group still had significantly (p < 0.01) safer attitudes towards all topics considered except airbags and tires. It should be pointed out that the significant effect on the learners with regard to speed was not due to a better attitude in the experimental group at the time of posttest 2 compared to the pretest, but was instead caused by the poorer results of the control group during the same period. No effect of age and gender were found in these analyses. The posttest 2 questionnaire (administered about 18 weeks after the risk awareness training) asked the learner drivers in the experimental group to rate the education given in the safety halls. In general, the respondents were very positive to the instruction, the average total rating was greater than 5 on a scale of 1 to 7. Also, the participants were very positive in their final verdict concerning the quality of the education they had received in the safety halls, with a total rating of almost 8 on a scale of 1 to 10. The ratings were lowest for the two topics tires and securing loads (7.32 and 7.27, respectively), and were highest for seat belts and speed (8.30 and 8.66, respectively).

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General discussion

5 GENERAL DISCUSSION The findings reported in the papers included in this thesis illustrate both the advantages and disadvantages of the Swedish licensing system, focusing on some specific issues related to the educational process, the outcome of the driving tests, and the effects on new licensees during their first period as inde‐pendent drivers. Two of the studies (papers III and IV) concerned the benefi‐cial effects of the reform allowing 16‐year‐olds to start practicing behind the wheel, which made it possible for learners to gain more driving experience before their debut as unsupervised novice drivers. In other parts of the re‐search (paper V), it was revealed that using an insight‐based educational ap‐proach conducted in safety halls can influence learner drivers’ knowledge and attitudes about the use of cars safety equipment (e.g., safety belts). However, findings also showed possible shortcomings of the Swedish licensing system, such as the difficulty to explain why 18–24‐year‐olds pass or fail the driving test (paper I); that training pursued in a more structured manner does not seem to be beneficial for the outcome of the driving tests (paper II); and that injury crashes do occur during the learning period (paper IV). The current investigations provide information that can be used to develop the Swedish licensing system in a way that will increase the potential of driver education to reduce traffic crashes among young drivers. Therefore, the fol‐lowing discussion concentrates on aspects reported in papers I–V, which can be implemented to improve the situation for young drivers in Sweden. It is likely that many of the findings can be applied to enhance licensing systems in other countries as well. However, it is important to understand that there are limitations in such transfer of found results. The possibilities to implement findings from Sweden is always influenced by national traditions, legal sys‐tems and other aspects that have not been included in the studies reported in paper I‐V.

5.1 Vision Zero and the Swedish driver licensing sys‐tem

As described in the first chapter of this thesis, the behavior and safety of young novice drivers depend on many different factors that are interrelated in a complex web. This has several implications when analyzing the potential of driver education to reduce traffic crashes involving young drivers. For exam‐

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General discussion

ple, numerous topics must be covered during the learning period to ensure that aspiring drivers have really understood and developed the competencies they need to be able to drive safely in traffic, which in particular means not being involved in road traffic crashes that lead to fatalities or personal injuries. The results reported in this thesis demonstrate that such crashes constitute a problem related to young drivers in Sweden, and the injuries that are incurred affect those individuals themselves (during both the practicing period and as new licensees) and other road users as well (see section 1.2.1, and papers II and IV). If driver education is considered to be an important component of attempts to reduce crash involvement among young drivers, the present findings suggest that changes need to be made in the Swedish driver licensing system. Inas‐much as studies have shown that the majority of young Swedish drivers are not involved in police‐reported injury crashes (e.g., Berg, 2001), it might be argued that the licensing system has been successful and does not need to be modified. However, the ultimate goal of traffic safety work in Sweden has been formulated by the Parliament as stated in Vision Zero, which includes an image of a future in which no one will be killed or seriously injured in traffic crashes (Tingvall, 2005). Therefore, it is unacceptable that young learner and novice drivers are involved in road traffic crashes that result in fatalities or se‐vere injuries. When stipulating priorities, the focus should be on the road us‐ers at highest risk, which is precisely what young drivers are. Also, there is evidence that many young drivers in Sweden do not manage to take their responsibility as road users seriously, which means that they do not obey the rules and regulations of the system as well as other groups of road users do. This is indicated by, for instance, the observations that young drivers use seat belts less often (Cedersund, 2006), and they are overrepresented in alco‐hol‐related fatality crashes (SRA, 2004a). Furthermore, it has been found that in many crashes involving deaths, young licensees have driven more than 30 km/h over the posted speed limit (SRA, 2004b). Most of these problem behav‐iors are especially exaggerated in young male drivers. According to Vision Zero, it is the responsibility of the system designers to manage the problem (Tingvall, 2005; Fahlquist, 2006) of reducing crash in‐volvement among young drivers. These experts include the providers of driver education, such as the SRA and the driving school organizations, and hence it seems that they must develop measures to increase the motivation of

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General discussion

individual young drivers to take their share of the responsibility for Vision Zero. Among other things, Vision Zero emphasizes injury prevention through measures applied inside the vehicle and in the road environment. The reason‐ing behind these efforts is that people normally make mistakes, even in traffic and also unintentionally. If young novice drivers make mistakes, the environ‐ment should be “forgiving” in order to prevent serious consequences. How‐ever, Vision Zero also stresses the importance of behaviorally oriented meas‐ures aimed at motivating drivers to abide by the rules and use the safety equipment in vehicles, which, for example, can be accomplished through im‐provement of speed adjustment skills and driver education. In addition, it is necessary to achieve the following: a decreased number of crashes during driver training; individualization of driver training in order to increase risk awareness; reduction of overestimation of driving skills among young males; and provision of insight about how group pressure, lifestyle, and personality can affect driving style and crash involvement. Throughout all this, it is also necessary to enhance the motivation to drive carefully and with greater safety margins.

5.2 Utilization of the reform allowing practicing at the age of 16

The positive effects of the change allowing learner drivers to begin behind‐the‐wheel practicing at the age of 16 years are reported in papers III and IV. One of the analyses (paper III) showed that the reform led to an approximately 40% reduction in the number of crashes among novice drivers who had taken ad‐vantage of practicing at the age of 16. However, despite the obvious beneficial impact on the safety of young drivers, the decrease after the reform was only 15% as a whole, which can be explained by the fact that only about half of the younger learners chose to start practicing as 16‐year‐olds. Therefore, to exploit the safety potential of the lowered age limit, a larger part of the young learner driver population must be persuaded to start early and practice more. Inas‐much as the reform applies only to that age group, the benefits of practicing from the age of 16 should be impressed upon those who really want to have a license by the time they are 18 or 19. On the other hand, it is more questionable whether measures should be taken to encourage as many people as possible to get a license at the earliest possible

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General discussion

age. The main reason for this reservation is that there is evidence that the younger the age at which a learner obtains a license, the higher the initial crash risk as a novice driver (e.g., Maycock et al., 1991). However, it can also be ar‐gued that earlier licensure leads to increased mobility, which can have many positive effects on aspects such as the chances of getting a job and opportuni‐ties to make social visits and take part in recreational activities (e.g., Berg, 2001). Therefore, it seems appropriate to develop measures to prompt as many young people as possible who have decided to get a license early to take ad‐vantage of practicing from the age of 16. Another positive effect of the 16‐year age limit is indicated by the finding that learners who started behind‐the‐wheel training at the age of 16 were more likely to pass the driving test (paper I).

5.3 Amount of driving practice The present results also show that the amount of time spent practicing was 2.5–3 times greater among those who started behind‐the‐wheel training at the age of 16 than among those who did not (paper III). After controlling for three confounding factors, the benefits of the increased practicing time could be seen as a 24% reduction in the crash involvement (crashes/10 million km). Further‐more, the cost‐effectiveness analysis described in paper IV showed that the benefits in terms of crash reduction after licensing were 30 times (crashes/1,000 drivers) or 10 times (crashes/10 million km) higher than the costs in terms of crashes occurring during driving practice. Therefore, the results reported in papers III and IV indicate that the quantity of practicing time per se is an es‐sential factor that can reduce crash involvement among the youngest novice drivers. This conclusion is valid even after considering the possibility that the lowered age limit for practicing would simply shift the high crash risk from young novice drivers to young learner drivers. The present observations that extensive driving is important both for acquiring experience and for reducing the crash risk for novice drivers concur with findings published by other re‐searchers (e.g., Maycock & Forsyth, 1997; Sagberg, 2000; Mayhew et al., 2002; Groeger & Brady, 2004). They also agree completely with the theoretical framework of Rasmussen (1986), which underlines the relationships between gaining experience, mental workload, and automatization of driving tasks. However, the Swedish national driver education curriculum does not empha‐size the importance of extensive practical experience and it does not stipulate any minimum requirements at all regarding aspects such as the amount of

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practicing that should be done by learner drivers, but instead leaves it up to the individual learners to decide for themselves. Studies conducted in Sweden and other countries have revealed that the amount of practice performed by learner drivers varies considerably (e.g., Maycock & Forsyth, 1997; Preusser et al., 1999; Gregersen et al., 2000; Gregersen & Nyberg, 2002; Mayhew et. al., 1999; Catchpole & Coutts, 2002; Nyberg & Gregersen, 2005), which clearly ex‐emplifies a lack of harmony in the triangle of goals – education – test de‐scribed in section 1.5.1. Based on observations discussed above and the results reported in papers III and IV, extensive driving practice—both in driving schools and with lay in‐structors—is recommended for all learner drivers, regardless of age. Different measures can be applied to accomplish that objective. For instance, learner drivers can be encouraged to practice extensively by giving them information about the importance of such a strategy. Furthermore, it might be appropriate to stipulate a minimum number of hours or kilometers that a learner must drive before being allowed to take the driving test; that approach is currently an ingredient in many graduated licensing systems, although there are diffi‐culties associated with ensuring that the practice driving is actually done for the required number of hours (McKnight & Peck, 2003). Notwithstanding, even without effective control of practicing time, such rules represent what the system designers refer to as a minimum, and this type of guideline does not exist in the current Swedish licensing system. Another problem is to decide how many hours or kilometers that should be required. In most of the graduated licensing systems using this approach, the minimum amount of practice is about 50 hours, which might not be sufficient to achieve a safety‐promoting effect. In the present work (paper III), the bene‐ficial impact of utilizing the 16‐year age limit for practicing was apparent after an average of 118 hours of driving. Also, Sagberg (2002) stated that practicing comprising about 5,000 to 7,000 km of driving before licensing is necessary to reduce crashes among novice drivers. All these findings must be considered when deciding if and how an increased amount of practicing should be re‐quired in a future development of the Swedish licensing system. Another matter that ought to be deliberated when discussing the amount of practice is whether there should also be a minimum period of time during which the learner driver should gain the experience. The current results (paper III) showed that those who took advantage of behind‐the‐wheel training over

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General discussion

a period of two years practiced 2.5–3 times more than those who did such training for only about six months. The obvious and not surprising conclusion that can be drawn from this is that it is easier to increase the amount of practic‐ing time, if the period of accumulating experience is longer. Clearly, it is also possible to practice a large number of hours or kilometers in a relatively short period of time, if so required by the system at hand. So in further studies, re‐searchers should address the question of what benefits can be achieved by stipulating a minimum length of the practicing period. If such a prerequisite should be incorporated in the Swedish licensing system, it must at the least be connected with some other requirement, for example a minimum number of hours or kilometers of driving. Otherwise, learner drivers will simply be able to drive fewer hours or a shorter total distance during a large portion of the stipulated driving period. Nevertheless, introducing a requirement of a mini‐mum period of driving as a learner would give beginners a signal that learn‐ing to drive is a process that takes time and that it should not be taken lightly or achieved as quickly and cheaply as possible. A study included in the evaluation of the 16‐year age limit (Gregersen et al., 2000) showed that even if the increased amount of driving among those utiliz‐ing the reform did promote safety, it did not improve their knowledge and attitudes. The crash reduction noted in the evaluation (paper III) was thus probably due solely to increased experience and reduced mental workload, not to higher risk awareness or better performance of specific driving skills. This is also in line with the theory of skill acquisition formulated by Rasmus‐sen (1986). Therefore, if improvement in these areas is to be accomplished through driver education, some other component is needed besides merely making it possible to acquire more driving experience. Furthermore, as pointed out in Chapter 1, it is obvious that there are problems related to many other factors affecting young novice drivers and their road safety (e.g., social preconditions, overestimation of driving ability, low use of seat belts, and motivation concerning why, when, and with whom driving is done) that cannot be solved solely by an extensive amount of driving during the learning period.

5.4 Structure of the learning period Learning to drive is a complicated endeavor, and in many cases complex tasks must be solved by the driver to achieve safe operation of the vehicle. This

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General discussion

means that a driver needs experience of many different traffic situations and environments to gain all the necessary competencies (Groeger, 2006), and that objective cannot be attained simply by driving for a large number of hours or kilometers. This agrees with the findings reported in paper II, which imply that not only the time/length, but also the content, of a driving session is of importance. More precisely, the study showed that young females practiced in a more structured way (e.g., that they planned their training) than their male counterparts, even though there was no gender‐related difference in the total amount of driving practice time. The fact that females conducted more organ‐ized training compared to males may be one of the explanations why they were involved in fewer crashes during the first year as licensed drivers. How‐ever, further studies are needed to elucidate the implications of these observa‐tions, since it was not possible to follow the same individuals through the training and novice driver periods. The need for a structured approach when learning to drive has been stressed in many reports (e.g., Gregersen & Nyberg, 2002; Hatakka et al., 2003; OECD, 2006), and this applies to numerous aspects, such as conducting components of training in a sequence based on the goals of the curriculum. It also includes practicing many different skills (i.e., not just “driving around”) and going from simple to more complicated tasks during the learning process, as well as developing the most suitable combination of the four levels and the three col‐umns of the GDE matrix. Furthermore, different training approaches must be used in an organized fashion, for example regarding how to combine profes‐sional instruction with lay‐instructed driving, or theory with actual driving. Therefore, one way of trying to enhance the positive effects of extensive driv‐ing practice is to incorporate measures during the learning period that can help the learner driver to structure the process of accumulating knowledge and experience. The necessity of structure also agrees with the theory de‐scribed by Rasmussen (1986) suggesting that to reach the skill‐based level (i.e., highly automatized behaviors), which is presumably important to be able to drive safely in traffic, a driver needs increased exposure to a variety of traffic situations in order to create a bank of routine and recognition. Thus there will be a qualitative disparity in the driving experiences gained by two different learners who do the same amount of training, but one drives in only a few en‐vironments and conditions and the other drives in many types. This hypo‐thetical situation may partly explain the dissimilarity in crash risk between male and female drivers (paper II).

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General discussion

The licensing system in Sweden leaves it completely up to learner drivers themselves to decide how to structure their training. The driving schools offer courses of study for both theoretical studies and practical driving, but learners are not compelled to choose such professional tuition. Furthermore, several of the present findings show that learners do not take advantage of structured studies in driving schools as much as they could, even though there is a sub‐stantial safety potential connected with a more organized period of learning. For example, it was found that crashes do occur during driving practice (paper IV), primarily when supervised by a lay instructor. This indicates that, among other things, a more structured approach is needed with regard to where, when, and how practicing should be done in order to minimize the risk that lay instruction will be performed under hazardous conditions that the learner driver is not prepared for. This conclusion is based on an in‐depth analysis of fatal crashes during practice conducted by Gregersen and Nyberg (2002), which showed that a large part of these traffic calamities occurred on slippery roads at high speeds. In the same study, it was found that learner drivers vary widely with respect to the amount of practice they perform, as well as the ar‐eas of the curriculum it covers. It was also shown that a large proportion (10–25%) of newly licensed drivers had never practiced certain skills (e.g., sitting posture, overtaking, and environmentally friendly driving) that are important for safety and are also included in the driving test. A subsequent study by Ny‐berg and Gregersen (2005) yielded similar findings. The study reported in paper II revealed that there is considerable variation in the proportions of the driving practice (both lay‐instructed and professionally supervised) that are allotted to practicing different skills, in different environ‐ments, and under different conditions. This indicates that the unrestricted Swedish system is used in a variety of ways by the learner drivers. Accord‐ingly, a reasonable question is whether this implies that the licensing system really produces novice drivers that actually have the competencies that are designated to be of importance in the national curriculum. The studies underlying this thesis were all performed when the national cur‐riculum essentially covered only the two lowest levels in the GDE matrix (see section 1.5.2). Nonetheless, as illustrated by the examples given above, there is no question that these two levels have been practiced to various degrees by learner drivers. The new national curriculum introduced in March 2006 en‐compasses the whole GDE matrix, thus it cannot be expected that the learner drivers of today will be able to practice and assimilate all the added elements,

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General discussion

unless the structure of the learning period is improved, specifically in relation to the two highest levels of the GDE matrix. A greater degree of professional‐ism must be applied when deciding how to design the education process. If this is not done, there is a risk that the new curriculum will be no more than a theoretical plan that will be impossible to follow and fulfill for all parties in‐volved (learner drivers, lay instructors, driving schools, and driving examin‐ers). If the Swedish system is not changed, it should at least be assumed that learner drivers must be informed of what is required of them (i.e., what is stipulated in the national curriculum) in order to be able to structure the learn‐ing period on their own. However, at the time of the present studies (papers I and II), no more than about 5% of the learner drivers had studied the national curriculum, which means that the majority of learners never read explicit de‐scriptions of what they ought to learn to develop the competencies considered to be necessary for safe driving (i.e., to pass the driving test). In paper I, it is suggested that they must have gained such knowledge in some other way, possibly by studying the most widely used driving instruction book, by par‐ticipating in classroom instruction at a driving school, or by using various types of computerized aids. However, this simply illustrates another problem‐atic issue related to the Swedish licensing system, namely, the matter of theo‐retical studies conducted by learners. The present results revealed that most of the theory studying was done at home and that 31% of the females and 41% of the males had never taken any classroom lessons at a driving school (paper II). This indicates that many learner drivers give low priority to theoretical studies, that they believe that they can learn what they need on their own, or that they do not understand the importance of studying theory to obtain the comprehensive knowledge required to become a safe driver. The proportion of applicants approved on the written test in Sweden has dropped dramatically in recent years. Considering 18–24‐year‐olds, 79% passed the test in 2000 but only 54% in 2005, a drop of 25% (Nilsson, 2007). This situation indicates the need to raise awareness about the importance of studying theory and also to find structured measures to integrate the learning of theory and practical driving. The latter aspect has also been recommended in several EU projects (e.g., Hatakka et al., 2003) and by the OECD (2006) in its report on crashes involving young drivers and effective countermeasures.

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General discussion

5.5 The driving license tests According to the present results (paper II), female learner drivers spend more time than males did studying both at home and in classroom lessons at a driv‐ing school to prepare for the written test. Notably, this seems to be beneficial as reflected by the fact that females also do better on the written test, as indi‐cated by national statistics (Nilsson, 2007). However, regarding the driving test, the present results could not clearly ex‐plain why 18–24‐year‐olds passed or failed on the basis of background vari‐ables and how they had practiced driving (paper I). The female learners used a more structured approach to behind‐the‐wheel training (paper II), but they did not benefit from this by doing better on the driving test, which is sup‐posed to measure if a driver has achieved the competencies stipulated in the curriculum or not. This suggests that it is very difficult to predict the outcome of the driving test by considering the training approach used by the learner driver. In this sense, it appears that the Swedish system is weak, since the study reported in paper I gave no clear indication of what a learner should practice to pass the driving test. There are numerous plausible explanations for these findings. For example, there might be problems related to how the driving test is conducted, which no doubt includes inter‐assessment differences, that is, the results for a par‐ticular applicant might vary depending on what examiner administers the test (Henriksson et al., 2004). That possibility is probably also one of the reasons that learner drivers applying to take the driving test as driving school students passed the test to a considerably greater extent than those applying on a pri‐vate basis (paper I), even though it reveals very little about how the training was actually done. Therefore, it might be more appropriate if the driving ex‐aminers did not know how the learner driver applied to take the test. As indicated in paper I, the impact of background variables on a model pre‐dicting the outcome of the driving test was less pronounced when it also in‐cluded the aspects of driver education and training circumstances. Therefore, it was concluded that background variables such as age, nationality, and gen‐der had at most an indirect effect on the results of the driving test, and thus it seems that there are no problems related to equal opportunities for license ap‐plicants in the Swedish system.

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General discussion

It is difficult to develop a driving test that covers all the goals of a modern driving curriculum, one reason being the limited time available for the actual taking of the test (Baughan et al., 2005). This leads to difficulties in a system like the one in Sweden, where it is up to the learner drivers to make their own choices about numerous facets of their training, such as the quantity, the con‐tent, and the traffic environment to be used in practicing; the distribution be‐tween lay instruction and professional education; how to structure the tuition; and what theory books and other learning aids to use. Due to the design of the Swedish driver education system, the license tests are the only means of veri‐fying that learner drivers have really acquired the competencies specified in the curriculum (Henriksson et al., 2004). Considering the difficulties related to the “old” Swedish licensing system that were detected in the present studies, it will be even more problematic for learner drivers to deal with all the goals of the new, more comprehensive GDE‐based national curriculum that is in use today. In particular, it is a challenge to know how to communicate to the learners what will be expected of them on the driving test in such a way that will actually influence how they chose to practice. It is also important to im‐press upon learners that all components of the driving license tests are de‐signed to be related to the goals of the curriculum and that they are assessed on a regular basis. If this is not done, there is a risk that learner drivers will assume that certain items will not be included, and hence they will not make an effort to learn those particular components (Nyberg & Gregersen, 2005). Therefore, it might be a good idea to develop some type of diagnostic check for following the development of the learner during the education process, which could be achieved in several different ways. An example of such an approach is the new GDE‐based national driving cur‐riculum that was implemented in Norway in 2005 (Norwegian Public Roads Administration, 2005), in which all learner drivers take mandatory lessons in‐corporating some of the curricular goals (Rismark & Sølvberg, 2006). Members of the EU project TEST (Baughan et al., 2005) have also suggested that fixed amounts and types of training be specified for some of the aspects in the GDE matrix instead of merely relying on the driving test. This would also ensure that all learners have received professional instruction regarding some of the most vital parts of the curriculum, and, at least theoretically, it would make it possible to actually stipulate certain competencies that should always be as‐sessed on the driving test. In Sweden, such an approach was included in the very inspiring STEFUS proposal that was presented to, but not approved by, the Parliament in 1999 (SNRA, 2000).

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General discussion

5.6 Mandatory driver education In Sweden, the only mandatory element of driver education has been the risk awareness training (often still referred to as skid training) which was intro‐duced in 1975. The present results suggest that there is a need for more com‐pulsory tuition in the Swedish licensing system, which might be the best way to achieve concordance between the goals of the national curriculum, the con‐tent and provision of driver education, and the license tests. When discussing the possibility of making more of the components of driving education compulsory in the Swedish licensing system, a number of aspects should be considered. Several studies have shown that learner drivers take an average of 12–15 hours of behind‐the‐wheel lessons at driving schools (e.g., papers I, II, and III; Gregersen & Nyberg, 2002), and hence that particular length of tuition can be used as a basis for discussing the number of lessons that should be mandatory. There has been a debate in Sweden (e.g., Nyberg et al., 2002; Linderholm & Bergman, 2002) that introducing mandatory lessons in driver education might lead to social inequality, in that learners from families with a lower income will not have the same opportunities to obtain a license. However, that suggestion is refuted by a study indicating that learner drivers with parents who have a lower education actually take a larger number of be‐hind‐the‐wheel lessons at driving schools (Gregersen et al., 2000). Most Swedish learner drivers combine professional instruction at a driving school with lay‐instructed training (papers I and II), and the majority of the hours spent practicing is done under lay supervision (papers I, II, and III). Fur‐thermore, it has been shown that extensive lay instruction has a positive im‐pact on the safety of young drivers. However, in the study reported in paper IV, it was also found that most (considering both number and severity of out‐come) road crashes involving learner drivers occur during lay‐instructed train‐ing. Clearly, if some changes are made (suggestions already mentioned), the benefits of lay‐instructed driving can be even greater. It should also be noted that the larger number of hours of practicing done by those who took advan‐tage of the 16‐year age limit was due to an increase in the lay‐instructed driv‐ing. The amount of practicing done with professional driving instructors was essentially the same as before the age‐limit reform and regardless of whether or not learners started driving at the age of 16. As pointed out above, most learners in Sweden take about 12–15 hours of behind‐the‐wheel lessons at a driving school, and they usually participate in such instruction at the end of the learning process. Accordingly, it is plausible that the effect of gaining ex‐

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General discussion

perience over a long period of time can be enhanced by making better use of the professional instruction. As suggested in paper IV, it might be possible to counteract the problems as‐sociated with non‐professional tuition by making lay instructors aware that it is important to structure the driving practice and giving them advice on how to achieve that objective (including telling them that some tasks require a pro‐fessional instructor and that it is essential to study theory). The suggestion of implementing a mandatory introduction course for lay instructors and learner drivers that was given in paper IV became a reality in January 2006. This represents a first and positive step towards improving the unstructured Swed‐ish system. The introductory course is also beneficial in that it creates natural interaction between lay instructors, learner drivers, and professional driving instructors, which in turn is expected to give rise to better collaboration between these ac‐tors, and allow them to appreciate each other’s different competencies and make use of them in a sensible way. For example, this might lead to a better combination of lay‐instructed and professional instruction. It seems that the observation that most learner drivers take professional behind‐the wheel les‐sons at the end of the learning period (paper I) might explain why only about 10% of the learner drivers reported getting “quite a lot” or “very much” sup‐port and/or advice from a driving school about how to organize their lay‐instructed practicing (paper II). A better combination of professional and non‐professional instruction would probably also increase the number of appli‐cants that pass the driving test, as observed in the study reported in paper I. Another example of what might be suitable to include as a mandatory part of the Swedish licensing system is the type of education evaluated in the study described in paper V, which addressed the issue of minimizing the conse‐quences if a crash does occur. As discussed in section 1.2, young novice driv‐ers are overrepresented in crash statistics and among those who do not use seat belts. Also the results reported in papers I and II show that the skills that are taught in safety halls, such as performing a safety check, securing loads, considering sitting posture, and wearing a seat belt, are practiced only to a small degree during behind‐the‐wheel training with lay and driving school instructors. Therefore, there seems to be a need for an education covering the kind of topics taught about in the safety halls. Also, the educational approach used in the safety halls does indeed influence learner drivers’ knowledge of

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General discussion

and attitudes towards using vehicle‐related safety equipment such as seat belts, securing loads, and adjusting sitting posture (paper V). Therefore, man‐datory safety hall instruction for all learner drivers would probably affect an‐nual crash statistics by increasing the rate of survival among young drivers involved in traffic crashes (e.g., Evans, 1991; SNRA, 2003; Nilsson, 2004). In addition, if as many drivers and passengers as possible wear a seat belt cor‐rectly (e.g., tighten it once it is fastened, position it close to the neck, and place the lap part over the pelvis instead of the abdomen), the outcome of many crashes will be less severe, and there will be a reduction in both human suffer‐ing and the economic costs to society. In a study by Nyberg and Engström (1999), learner drivers who were interviewed 4–6 weeks after education in a safety hall stated that they had changed their behavior in relation to the use of seat belts. Also, in an evaluation of a new national curriculum for risk aware‐ness training in Sweden (Engström et al., 2001), learner drivers who were in‐terviewed said that attending a safety hall during their mandatory risk aware‐ness training had prompted them to use a seat belt more regularly. Moreover, it has been found that the Swedish project designated PILOT, which was a fur‐ther education program for novice drivers, had a significant positive impact on self‐reported use of seat belts, and that effect lasted at least two years (Nolén et al., 2002), probably due to the educational approach that later gave rise to safety halls. Consequently, considering both the results presented in paper V and previous findings (Nyberg & Engström, 1999; Engström et al., 2001; Nolén et al., 2002), it is reasonable to assume that the use of appropriate methods in safety halls will lead to increased and improved wearing of seat belts, which in turn should be beneficial for the outcome of many crashes in‐volving young drivers. Good knowledge and attitudes concerning the other topics covered in safety halls (i.e., airbags, securing loads, sitting posture, speed, and tires) can also have a significant impact that can save lives and lessen the severity of the out‐come of crashes. For instance, sitting posture is important because it is closely connected with how a seat belt can be correctly fitted around the body, and it also has a substantial effect on how well protected the driver is if the car is hit from behind by another vehicle. Regarding loads, much can be gained if driv‐ers understand that even small, loose objects can cause extensive bodily injury if a crash occurs. Moreover, in the study reported in paper V, a greater effect on drivers’ choice of speed was achieved by adding safety hall education than by giving only the mandatory risk awareness training. However, this impact

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General discussion

was relatively small and had almost disappeared 18 weeks after the safety hall instruction. Therefore, considerable effort should be made to develop a special exercise focused on speed in order to influence young drivers, particularly be‐cause none of the exercises now included in the safety halls deal with that par‐ticular topic. The information provided in safety halls can be described as insight‐based education. This concept has recently been employed in some European coun‐tries in an attempt to renew the strategies used for instruction of learner driv‐ers, as exemplified by the existing mandatory risk awareness training in Swe‐den and what is known as the second‐phase training in Finland. The term an‐ticipatory skills is sometimes used instead of insight, but no matter which des‐ignation is applied, it is important to emphasize that the aim of this approach differs from the objective of traditionally skill‐based driver training. Rather than trying to improve the technical ability of drivers to control vehicles, in‐sight training focuses on communicating an awareness of the need for using large safety margins. Insight training also addresses the problem of overconfi‐dence by including exercises in which drivers are expected to recognize their own limitations. Accordingly, the basis of this concept is that it is more impor‐tant to instruct drivers about how to use safety equipment and how to adopt a driving style that will help them predict and avoid critical situations in traffic, than it is to try to teach them advanced skills to handle critical events when they actually occur. Both practical exercises (e.g., emotional experiences of forces in traffic or driving style demonstrations) and theoretical drills (e.g., group discussions or advice on a safe driving style) can be used to accomplish that objective (e.g., Gregersen, 1998; Nyberg & Engström, 1999; Nolén et al., 2002; Katila et al., 2004). The insight‐based educational approach might also be suitable to help accom‐plish the training dimensions “risk‐increasing factors” and “self evaluation” in the GDE matrix. In addition, it confirms the need for assistance from profes‐sional instructors during the learner period, since it is not likely that lay in‐structors can manage to teach these higher order skills. Therefore, this type of educational approach should be considered if and when authorities consider making further elements of the Swedish licensing system mandatory. The current findings regarding crash conflict types (papers II and IV) and cir‐cumstances (paper II) related to novice drivers also suggest that compulsory tuition focused on speed (known to be a major factor in most single‐vehicle

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General discussion

crashes) and driving during darkness can have beneficial effects on young drivers, especially males. Furthermore, a proposal for extended mandatory risk awareness training in Sweden is awaiting approval by the Parliament. This proposition has been submitted by the SRA and suggests that the existing risk awareness and skid training should focus more extensively on speed ad‐aptation and use of seat belts, and that a new, also compulsory, risk awareness training should be implemented to present information on alcohol, drugs, and fatigue in connection with driving. If implemented, this initiative will no doubt have a positive effect, since it would ensure that, on at least at one occa‐sion during the learner period, all novice licensees will have received informa‐tion and experience under the supervision of professional instructors with re‐gard to issues that are very important for this category of drivers. Furthermore, some of the findings discussed here indicate that studying the‐ory increases the future safety potential of learner drivers and also helps them pass the license tests, which implies that a certain amount of classroom tuition should be made mandatory in order to accomplish the task of creating safe drivers. Also, it might be beneficial to structure theory studies in classroom lessons at a driving school, since it was found that female learners used that approach, and, according to the national statistics, they did better than males on the written test (paper II). In addition, it was noted that the crash rates dur‐ing the initial period of licensure were lower for females than for males, thus it seems that better theoretical knowledge should have a positive impact on crash involvement among newly licensed drivers. This interpretation is sup‐ported by other findings obtained in Sweden (Wiberg, 2006).

5.7 Restrictions on novice drivers Applicants who pass the license tests in Sweden are issued a probationary li‐cense that is valid for two years, but they are not affected by any rules, regula‐tions, or restrictions other than those imposed on drivers with a permanent license. Since it has been found that restrictions in graduated licensing systems can low the rate of crash involvement (i.e., minimizing exposure to risky situa‐tions) among novice drivers (Williams, 2006), it is likely that that strategy would also be beneficial if implemented as a component of the probationary period in the Swedish licensing system. The present findings regarding con‐flict types and the associated circumstances (papers II and IV) indicate that restrictions on night driving and speed would be most beneficial in Sweden. The need for limitations during the probationary period is also suggested by

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General discussion

the current results showing that the learning period is relatively safe with re‐gard to the rate of injury crashes, especially compared to such crashes occur‐ring during the first period as a novice driver (paper IV). This was seen as a more than 30 times higher risk of being involved in an injury crash (i.e., crashes per 1,000 drivers) during the first two years of licensure than during practicing as a learner. Similar observations have been made in other countries as well, for example, Forsyth et al. (1995) estimated that in the United King‐dom the crash rate was at least 20 times higher during the first year of licensed driving than during the learning period. There would be many problems associated with implementing restrictions on new licensees, for instance regarding how to induce this category of drivers to obey the restrictions and ensure that enforcement of violations is imple‐mented, and considering how limiting the mobility of these young people might affect aspects such as their chances of getting a job. It should be pointed out that several investigations have indicated that violations of different re‐strictions are quite common (e.g. Williams et al., 2002; Steenbergen et al., 2001; Simons‐Morton & Hartos, 2003; Agent et al., 2001; Begg et al., 1995; Harre et al., 1996; Mayhew et al., 1998; Mayhew et al., 1999). Also, it would no doubt be a delicate matter to obtain public support for restrictions, since they might be regarded as unfair, considering that all novice drivers have passed the license tests and should therefore be competent and safe drivers. Consequently, when discussing restrictions, it is perhaps of particular importance to bear in mind that a decision has to be made in relation to the balance between the mobility and the safety of young drivers (Williams, 2006). Moreover, as pointed out by Berg (2006), the majority of young novice drivers are not involved in crashes, but that group would nonetheless be affected by general restrictions on new licensees, which theoretically could even lead to a lower general level of health in those individuals. However, it is not certain that having to walk, ride a bi‐cycle, or take a bus or train due to restrictions on driving would be detrimental to the health of young people. Considered from the standpoint of traffic safety, implementation of restric‐tions would probably lower the rate of crashes involving young novice drivers in Sweden. Or, from another perspective, the need for restrictions during the probationary period depends on whether educational changes in the licensing system can be assumed to improve the situation for young novice drivers. If not, restrictions probably represent one of the best countermeasures available to lower the crash risk for young, newly licensed drivers.

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General discussion

5.8 Application of the present results to licensing systems in countries other than Sweden

The present results indicating that extensive driving during the learner period can reduce the rate of crashes for young novice drivers is probably valid inde‐pendently where in the world this would be applied. However, it is probably easier to increase the motivation to practice much among parents and learner drivers in countries that have a well‐developed licensing system and a tradi‐tion of allowing private supervision of behind‐the‐wheel training. Learner drivers in Sweden have long been able to choose freely between train‐ing with lay instructors or at professional driving schools. Practicing with par‐ents is very widespread and may turn out to be a vital precondition for achiev‐ing the considerable increase in private driver training associated with chang‐ing the driving age limit to 16 years for learners. By contrast, in a country with little tradition of behind‐the‐wheel practicing supervised by non‐professionals, the effect on the quantity of driver training may be less, thus the effect on the crash risk for young novice drivers may not be as good as in Sweden. This is exemplified by the case in Norway, where lowering the age limit to 16 years for practicing did not lead to the same increase in training as was seen after the equivalent reform in Sweden (Sagberg & Gregersen, 2005). The licensing age is also an important factor. In Sweden, a license can be obtained at 18, and it is doubtful whether the effects of lowering the age for practicing will be the same in a country where licensure is possible for 16‐ or 17‐year‐olds, since this would imply permission to drive under supervision from the age of 14 or 15, if the preconditions of the period of time to gain experience are the same as in Sweden. All countries could presumably benefit from the training approach described in paper V, which focuses on how to minimize the consequences in the event of a crash. In a country that does not have a broad driver education program, or does not have the possibility of creating such tuition, incorporating an edu‐cational approach such as that offered in safety halls concerning the use of car safety equipment could potentially lessen the severity of crash outcomes and save many young drivers lives. Certain learning aids incorporated in safety halls are already in use in different parts of the world, which suggests that there is a potential that this educational approach can be successful regardless of cultural disparities.

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General discussion

5.9 Future research There is a need for increased knowledge about how the goals of driver educa‐tion are fulfilled during the actual learning process and to what extent they are covered by the license tests. In addition, more studies should be performed to determine what type of structuring of behind‐the‐wheel practicing is most beneficial and to examine the relationship between theory and practice when learning to drive. Attention should also be given to finding out whether the more basic maneuvering skills should be taught before, after, or in combina‐tion with learning of higher order skills such as risk awareness and self as‐sessment. It is important to understand these interactions, because many fac‐tors in the GDE matrix make it necessary for the learner driver to have some type of previous knowledge or experience of driving to be able to reflect over situations and make reasonable self evaluations. Therefore, research should be performed to determine what amount of previous knowledge of driving re‐lated aspects a learner driver must have to be able to benefit from various measures included in a licensing system. It is also important to ascertain in what areas a learner driver has previous knowledge when entering the driving licensing system, for example regarding traffic rules and traffic behaviors, as well as his/her attitude towards traffic safety. This information could also help clarify why different learner drivers use the licensing system in disparate ways with respect to issues such as how much practicing is performed and the ex‐tent of training for professional instructors. Considering the present discussion, it is obvious that a vast amount of re‐search has focused on young drivers. It is also apparent that it is very difficult or perhaps even impossible to find any causal relationships between the vari‐ous factors that have an impact on the crash risk of young drivers. Therefore, it would be highly useful to be able to perform an investigation in which the same individuals (and data on their social and individual backgrounds) could be followed with regard to the learning period, the outcome of the license tests, and the driving record during the first few years as licensees. This would make it possible to determine how different training approaches and individ‐ual and social preconditions affect the possibility of passing the license tests and the crash involvement of novice drivers. However, a problem with such a longitudinal approach is that it would require a very large sample of indi‐viduals to provide enough statistical power when analyzing the relationships between various subgroups of drivers with respect to aspects like choice of learning strategies and crash involvement. Furthermore, it would be difficult to control for confounders such as self‐selection bias among the participants.

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General discussion

There are longitudinal studies available, such as the Cohort I study (Forsyth, 1992 a, b; Forsyth et al., 1995; Maycock & Forsyth, 1997) and the currently on‐going Cohort II study (Crinson & Grayson, 2005) in the United Kingdom. However, for Swedish driver education it is crucial to have these types of data from a national Swedish setting to improve the chances of drawing correct conclusions about what measures during the learning period should be im‐plemented to lower the crash rates for both learner and novice drivers. More research is also needed to determine the best way for learners to gain driving experience, in order to enhance the safety‐promoting potential of a large amount of driving practice. But what is best? To drive extensively over a short period of time or spread out such training over a longer period? To prac‐tice comprehensively in a few traffic environments, situations, and conditions, or to obtain more varied experience? How much practicing is needed to gain enough experience to manage driving alone? What are the possible benefits of stipulating the minimum length of a practicing period and/or a minimum number of hours or kilometers that a learner must drive before being allowed to take the license tests? How could better use of professional instruction in‐crease the effect of abundant driving experience? These are just a few of the important questions in this context. Much research has been done to identify the competencies that are required to be able to drive safely. However, more work is needed to develop and evalu‐ate methods that will enable learner drivers to acquire the necessary compe‐tencies and motivation. In other words, we must discover, among other things, what teaching methods are most appropriate, how much time is needed for each element in the instruction, and what combination of educational aids is best for each area of interest. For instance, the possible advantages of using insight‐based education should be further elucidated, and methods should be developed for applying that type of tuition. It would also be useful to continue investigation of what can be gained by individualized driver training by using methods such as the ones formulated by Linderholm (2000) in Sweden. Both these strategies are important, because research has shown that certain groups of young drivers have bigger problems than others (e.g., in relation to gender, personality, or lifestyle). There is also a need to better understand what parts of driver training might be more effective if they were mandatory. This might include driving theory and other compulsory lessons covering elements such as how to use the safety

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equipment in a car to minimize the consequences of a crash, speed adaptation, driving in darkness, and the psychological and social aspects of driving. Another important issue concerns determining the most appropriate way to evaluate different driver training strategies. It can be questioned whether crash involvement is the best criterion to use in such assessments, especially because driver training is only one of many components that might explain why a crash occurs (Dorn & Barker, 2005). Also, using crash data requires very large samples of drivers to provide sufficient statistical power. Therefore, it is necessary to determine whether measures of other factors, such as changes in knowledge, attitudes and/or self‐reported behavior, can adequately aid deci‐sions regarding modification of driver training. To a limited extent, evaluation of driver training methods has also been achieved by analyzing changes in ac‐tual driving behavior, in some cases by use of instrumented vehicles, but fur‐ther experience is needed to establish the benefits of such strategies. Moreover, it is important not to overlook results concerning the apprehensions of learner drivers in relation to different training approaches. A method that learners deem to be beneficial is more likely to have positive effects on training out‐come than a technique that is regarded as unfavorable. In summary, it is nec‐essary to address the issue of whether evaluations that combine measures of learner drivers’ apprehensions of training methods, changes in knowledge, attitudes and/or self‐reported behavior, and actual driving behavior can be just as efficient as determining crash involvement when attempting to predict the influence of driver training strategies.

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General discussion

88

Conclusions and suggestions

6 CONCLUSIONS AND SUGGESTIONS The findings in the five papers included in this thesis can be used as an incen‐tive for further analysis of driver education and to stimulate future discussions of the development of the various components of the Swedish driver licensing system. This should be done in order to fully utilize the potentials of these schemes and as a means of reducing traffic crashes among young drivers. The current studies have resulted in the following conclusions and suggestions:

• Young drivers in Sweden—both learners and newer licensees—are involved in crashes that lead to fatalities and severe injuries. In ac‐cordance with Vision Zero, the Swedish driver licensing system must be changed to avoid these crashes in the future and to fully exploit the potential of driver education.

• If a larger part of the youngest learner driver population can be per‐

suaded to start practicing early and practice more, it may be possible to take better advantage of the safety potential offered by the low‐ered age limit for behind‐the‐wheel training.

• Many hours of supervised practicing before licensure can enhance the safety of novice drivers. Therefore, continuous and extensive practice should be encouraged, and any measures implemented to reduce crash involvement during behind‐the‐wheel training should not lead to fewer hours of practice.

• The learning period should be better organized, which includes im‐

proved agreement between the goals of the national curriculum, the content/process of driver education, and the design of the license tests.

• The driving test should be changed so that it actually determines

whether the defined objectives of driver education have been ful‐filled, and to make it possible to discern differences between those who fail and those who pass.

• Professional instruction of learners in both the theory and the prac‐

tice of driving should be a more prominent component of driver

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Conclusions and suggestions

education. Such an approach would provide continuous support and structure in the learning process, and it would make it possible to cover aspects of the national curriculum that lay instructors and learner drivers cannot be expected to handle themselves.

• Parts of the Swedish licensing system should be made compulsory to

help solve the problems of young drivers and to fulfill the goals of the national curriculum.

• In Sweden, the concept of safety halls is contributing to the devel‐

opment of safe drivers. This is an example of a measure that might be beneficial for all learner drivers.

90

Acknowledgements

ACKNOWLEDGEMENTS I would like to express my gratitude to the following organizations for funding of my research: SRA in Borlänge, VINNOVA, and VTI.

I am also sincerely grateful to the many people who have, in various ways, sup‐ported me or contributed to my work over the years—unfortunately, it is not possi‐ble to mention all of their names. I owe particular gratitude to my supervisor, former colleague, friend and co‐author, Nils Petter Gregersen at NTF, for his wisdom, guid‐ance, and never‐ending support and encouragement. I am also most grateful to the other co‐authors of the papers in this thesis; Inger Engström, Sixten Nolén, Hans‐Yngve Berg, Mats Wiklund, and Per‐ Arne Rimmö (deeply missed). I could not have done this without your support and encouragement. Special thanks to Anders Englund, Professor Emeritus at Uppsala University for introducing me to the world of traffic research, and to Joakim Tiséus who took the step into that world at the same time. I would also like to express my appreciation to Toomas Timpka at Linköping Uni‐versity for accepting me as a doctoral student; Anders Englund, Nils Petter Gre‐gersen and my research colleagues Inger Engström and Sixten Nolén at VTI for valu‐able comments on this thesis; Kent Lindqvist and Kåre Rumar for good advice re‐garding my work; Åsa Forsman, Mats Wiklund, and Anna Vadeby at VTI for their patience when answering my statistical questions; Urban Björketun, Ulf Brüde and Alexander Obrenovic at VTI for providing me with crash data to analyze; the people at the VTI library (special thanks to Catharina Arvidsson) for helping me find rele‐vant literature; Bengt Jansson, Tommy Ström and Roland Carlstedt at the VTI por‐ter’s office for fast and efficient help when I needed different materials; Anette Ohlqvist and Susanna Zalavary at the VTI switchboard for keeping track of my whereabouts and for always making me feel welcome when I arrived at VTI; Gunilla Sjöberg at VTI for various types of administrative aid in the making of this thesis; and Inger Forsberg and Helena Hellsten for assistance with the administration of questionnaires. Many thanks also to Jonna Nyberg for painting the cover of this the‐sis; and to Patricia Ödman for excellent revision of my English text in papers I, II and V, and the thesis, I am most grateful for your work and that you often suggest alter‐natives. I am grateful to Per‐Olof Grummas Granström, Hans‐Yngve Berg and Hans Mattsson at the SRA in Borlänge, and Joakim Tiséus at VINNOVA. You have all been my offi‐cial contacts with the financing organizations and have also encouraged me in my work. Further thanks go to Hans Tvetmark, as well as Thomas Lekander at the SRA in Borlänge, for providing me with data on license holders; Per‐Olof Nilsson at SRA in Linköping for data regarding the outcome of the written and driving tests; and

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Acknowledgements

Inger Forslund at SCB for some of the crash data I used. I am also obliged to Hans Erik Pettersson and Sonja Forward at VTI for social support during my postgraduate studies. I would also like to thank the following people for fruitful and inspiring discussions about driver training over the years: Lars Gustavsson (former president of the Swed‐ish National Association of Driving Schools); Rune Gustavsson and Rolf Bogmark (presidents of the skid track organizations TÖP and SkidCar, respectively); Widar Henriksson, Anna Sundström, and Marie Wiberg at Umeå University; and Marie Hasselberg and Lucie Laflamme at Karolinska Institutet. I am extra grateful and would like to express my great appreciation to Inger Eng‐ström and Sixten Nolén at VTI for continuing to work with me on projects concern‐ing driver training, for being such good friends, for infinite support and understand‐ing of the difficulties connected with conducting work on a thesis in parallel to other ordinary VTI projects, and for putting up with my positive nature! The same is true for my former colleagues Hans‐Yngve Berg and Nils Petter Gregersen. Many thanks are also due to Kajsa Rothman at Linköping University, for always being there and answering my questions about different issues related to the preparation of this the‐sis. I would also like to express a special thanks to all present and former colleagues at VTI at the divisions where I worked over the years, which includes staff at the former divisions TT and TMS and the current division TST. Thank you all for being such nice colleagues! I am also grateful to Elvis Presley and David Coverdale for their inspiring music, which has helped me through many difficult periods during the making of this the‐sis; the Leksand Stars who have unfortunately made me understand that life is nei‐ther fair nor easy; my parents Stig and Ellen Nyberg, my brothers Erik and Johan Nyberg, and my parents‐in‐law Sven and Mona Malmström for their support over the years. Finally, all my love to my beautiful wife Jonna and my gorgeous children Vilgot and Vilma. I do not understand what I have done to deserve your love, but I am most grateful. I promise that I will make up for the many late hours working on the thesis. I love you more than life!

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