Research report no.12 2005
In the driver's seat:
Understanding young adults' driving behaviour
A report on the ATP Young Drivers Study from the collaborative partnership between the Australian Institute of Family Studies, the Royal Automobile Club of Victoria and the Transport Accident Commission of Victoria.
by Diana Smart and Suzanne Vassallo
with Ann Sanson, Samantha Cockfield, Anne Harris, Warren Harrison and Allison McIntyre
1. Introduction
This report of the ATP Young Drivers Study is the product of a collaborative partnership between the Australian Institute of Family Studies, the Royal Automobile Club of Victoria (RACV) and the Transport Accident Commission (TAC) of Victoria. The collaboration commenced in 2002 when the RACV and TAC commissioned the Institute to collect and analyse data concerning the nature and development of driving behaviour among a large group of Victorian young adults (aged 19-20 years) who were participating in the Australian Temperament Project (ATP). The RACV and TAC worked in close partnership with the Institute during all phases of the project, including the preparation of measurement instruments, determining the nature of the analyses undertaken, the interpretation of study findings, and the preparation of this report.
This report provides valuable new information relating to young adults' own reported driving behaviour and their experiences when learning to drive, as well as providing a detailed examination of factors, past and present, which may have contributed to their current driving behaviour. It is hoped that this information will be used to increase understanding of the factors that place a young person at risk of becoming involved in a crash, committing traffic violations, and/or engaging in "risky" driving practices and, in turn, inform road safety programs aimed at preventing young people from engaging in potentially dangerous driving behaviours.
Research concerning young novice drivers is now briefly reviewed.
Over-representation of young drivers in traffic accidents
According to the Australian Bureau of Statistics, the leading cause of death among young Australians aged between 15 and 24 years is injury, and transport accidents account for more injury-related deaths than any other cause (ABS 2003). Within Australia, young drivers are significantly over-represented among those killed or injured in road traffic accidents (Cavallo and Triggs 1996; Dunsire and Baldwin 1999; Palamara et al. 2001; TAC 2003). For example, in the State of Victoria, young drivers aged 18 to 25 years accounted for 28 per cent of all drivers killed in 2002, despite the fact that they represented only 14 per cent of the licenced population (TAC 2003). Crash involvement is particularly high for young novice drivers, with the TAC (2003) reporting that young Victorians are almost four times more likely to be involved in fatal or serious injury crashes during their first year of driving than more experienced drivers.
This trend for disproportionately high levels of crash involvement among young drivers is not unique to Australia. The same phenomenon has been observed in many other industrialised countries or regions including the United States, Canada, New Zealand, the United Kingdom, and Europe (Begg and Langley 2000; Clarke et al. 2002; Engström et al. 2003; Laapotti et al. 2001; Shope et al. 2001).
Considerable research has focused on the crash patterns of young adults and the situational factors associated with crash involvement among this group. However, much less is known about the circumstances, characteristics or factors in young drivers' earlier lives that may have contributed to their later risky or dangerous driving behaviour (Engström et al. 2003; Shope et al. 2001). While acknowledging the important influence of situational (such as traffic conditions, time-of-day), structural (such as road design, road conditions), and community (such as norms/laws regarding driving behaviour, enforcement of road laws) factors on driving behaviour, this report aims to address this research deficit by primarily focusing on young driver characteristics such as their past and present individual attributes, and features of their current and earlier family and social environments.
Factors associated with crash involvement
As noted, there is an over-representation of young drivers in road traffic accidents. A number of studies suggest that the crashes that young people are involved in tend to be different from those of other age groups. To provide some background on the nature of these differences, a brief review of some of these characteristics now follows.
Crash type
Young inexperienced drivers are over-represented in most types of crashes but particularly single-vehicle crashes (Cavallo and Triggs 1996; Clarke et al. 2002; Engström et al. 2003, Palamara et al. 2001; TAC 2003). These crashes typically involve a single vehicle colliding with a fixed object (such as a tree or pole), or rolling over. More than half of 18 to 25 year-old drivers killed on Victorian roads in 2002 were involved in a crash of this type (TAC 2003). Young men are more likely to be involved in crashes resulting from excessive speed, whereas inadequate driving skills are more likely to play a causal role in crashes involving young women (Cavallo and Triggs 1996; Triggs and Smith 1996).
Time and day at which crashes occur
While the risk of being involved in a crash is highest at night for all age groups (Cavallo and Triggs 1996; Clarke et al. 2002; Triggs and Smith 1996), this risk is particularly high for young drivers (Cavallo and Triggs 1996; Chen et al. 2000; Clarke et al. 2002; Engström et al. 2003; Palamara et al. 2003; Triggs and Smith 1996). Sixty per cent of young drivers killed in Victoria in 2002 were involved in crashes between the hours of 8 pm and 6 am (TAC 2003).
Young drivers are also particularly at risk of being involved in a crash on weekends (Engström et al. 2003). In Victoria in 2002, fatality crashes among young drivers most commonly occurred on Fridays (23 per cent), Saturdays (25 per cent) and Sundays (15 per cent) (TAC 2003).
Alcohol and marijuana use
Crashes involving alcohol are more common among young drivers (Cavallo and Triggs 1996; Dunsire and Baldwin 1999; Engström et al. 2003). While research suggests that young drivers do not drive under the influence of alcohol more frequently than older drivers, it appears that when they do, they are at higher risk of being involved in a crash (Cavallo and Triggs 1996; Engström et al. 2003). For example, Palamara and colleagues (2001) compared crash rates among three cohorts of Western Australian drivers and found that a higher proportion of first year drivers were involved in crashes at low Blood Alcohol Concentration (BAC) levels (up to 0.099 gm per cent) than those with five or ten years licensure.
The relationship between crash involvement and marijuana is less clear. Although marijuana is the most common psychoactive substance after alcohol found in the blood of motorists involved in crashes (Begg et al. 2003), its role as a causal factor in these crashes is unclear (Begg et al. 2003; Fergusson and Horwood 2001). For example, Fergusson and Horwood (2001) examined the relationship between marijuana use and crash involvement among a large sample of young adults living in New Zealand. While they found a higher rate of "at-fault" crashes among regular marijuana users than non-users, they concluded that the elevated crash rate among this group appeared to be largely due to the characteristics of the marijuana users (that is, they were more prone to "drink-drive", engage in other risky driving behaviours, and to have attitudes favourable to driving violations) rather than the effects of the drug itself. The findings of Begg and colleagues (2003) supported this conclusion.
Nevertheless, recent research suggests that there may be a direct connection between marijuana use and crash involvement. A large Australian study (Drummer et al. 2004) which examined the relationship between drug use and crash culpability among 3398 fatally injured drivers of a variety of ages (not just young drivers) found a significant association between THC (the main psychoactive agent found in marijuana) and crash responsibility. After taking into account a wide range of factors associated with each crash (the condition of the road and the vehicle, the driving conditions, crash type, witnesses' observations, obedience of the road law, the difficulty of the task and level of fatigue), drivers with THC in their blood were significantly more likely to be found "responsible" for the crash that killed them, than drug-free drivers. This association was particularly apparent for drivers with THC concentrations of 5ng/ml or higher, with the likelihood that these drivers being found "culpable" being similar to drivers with BAC levels of at least 0.15g per cent. THC was also found to increase the likelihood of crash culpability in drivers who had been drinking alcohol.
Gender
Overall, young male drivers are involved in more crashes than young female drivers (Cavallo and Triggs 1996; Engström et al. 2003, Clarke et al. 2002; Vick 2003). For example, almost 80 per cent of young drivers (18-25 years old) who died in a motor vehicle crash in Australia in 2002 were male (Australian Transport Safety Bureau 2003). The proportion of young male traffic fatalities was even higher within Victoria during this time period (88 per cent) (Australian Transport Safety Bureau 2003).
However, males tend to drive more often than females (Kweon and Kockelman 2002; Richardson 2001). Consequently, once exposure (the number of kilometres driven) is taken into account, this gender difference in crash rates disappears, with the crash risk per kilometre for young Australian males and females generally being similar (Cavallo and Triggs 1996; Engström et al. 2003).
Passengers
Some research suggests that young drivers are at higher risk of being involved in a crash than older drivers if they are carrying passengers (Cavallo and Triggs 1996; Chen et al. 2000). For example, Chen and colleagues (2000) examined data relating to all fatal crashes within the United States between 1992 and 1997, and found that the risk of fatal injury increased for younger drivers (16-17 years) with the number of passengers carried in the vehicle. Compared to other drivers of the same age without passengers, the risk of fatal injury for a 16-year old driver with one passenger was 1.86 times higher; 2.58 times higher with two passengers; and 3.07 times higher with three passengers. In contrast, the risk of death for older drivers (30-59 years) decreased if there were passengers in the car.
Speed
Another factor that is often associated with crashes among young drivers is speed (Clarke et al. 2002; Engström et al. 2003). Speeding is the most common driving offence amongst young drivers, and excessive speed is implicated in many crashes among this age group (Clarke et al. 2002; Engström et al. 2003; Palamara et al. 2001). For example, excessive speed was judged to play a role in about 20 per cent of crashes involving first year licenced drivers in Western Australia in 1998, compared with only 10 per cent of crashes involving drivers who had held their licence for ten years (Palamara et al. 2001).
Fatigue
Research suggests that young drivers are involved in more fatigue-related crashes than older drivers (Clarke et al. 2002; Dobbie 2002; Engström et al. 2003). In an analysis of fatigue-related crashes in Australia between 1990 and 1998, Dobbie (2002) found that when the amount of driving exposure was taken into account, fatigued male drivers/riders aged between 17 and 24 years had the highest rate of single vehicle crashes, and were involved in more early morning (midnight to 6am) crashes than any other age group.
Seat-belt use
There is some research evidence that suggests that seat-belt use is less common in young drivers than other age groups, particularly young men (Begg and Langley 2000; Engström et al. 2003; Senserrick and Harrison 2000; Triggs and Smith 1996). For example, Senserrick and Harrison (2000) examined seat-belt-related attitudes and behaviours among 954 Victorian drivers, and found that young drivers (aged 17-25 years) were more likely than older drivers (aged 51-90 years) to display a poor road safety profile, characterised by inconsistent seat-belt use, less favourable attitudes towards seat-belt use and road safety, and a more negative perception of their own driving ability.
In another study, Begg and Langley (2000) examined rates of self-reported seatbelt use among 948 New Zealander young adults (aged 21 years) and found that only 70 per cent of young male drivers reported using a seat-belt at all times compared with 85 per cent of young female drivers. Forgetfulness, discomfort and a perceived low risk of injury were the most common reasons cited by participants in this study for not wearing a seat-belt.
Explanations for the higher rate of crashes among young drivers
A number of explanations have been posited for the high crash rate among young drivers. These include inexperience, age, risk-exposure, and risk-taking.
Inexperience
Inexperience seems to be a major contributor to the high crash rate among young drivers. Support for this conclusion can be found in the observation that crash risk decreases with driving experience, with the first few months of driving being considered the most dangerous (Cavallo and Triggs 1996; Engström et al. 2003).
New drivers tend to have poorly developed vehicle control skills and lack many of the cognitive and perceptual skills needed to make them safe and effective drivers (Cavallo and Triggs 1996; Triggs and Smith 1996). Research suggests that inexperienced drivers tend to underestimate the level of risk associated with certain types of driving behaviour or situations, and overestimate their own level of driving ability or capacity to deal with such situations. Furthermore, inexperienced drivers tend to have greater difficulties in anticipating and accommodating the behaviour of other road users and in dividing their attention between competing driving tasks than more experienced drivers. Vehicle control skills increase rapidly with experience, however, perceptual and cognitive skills are slower to develop (Cavallo and Triggs 1996; Triggs and Smith 1996).
Not surprisingly, research suggests that young drivers who gain high levels of supervised driving practice prior to attaining their driving licence are at less of risk of being involved in a crash than other young drivers (Engström et al. 2003). On the basis of this research, Victorian road safety authorities have introduced comprehensive road safety programs aimed at encouraging learner drivers to gain high levels of supervised driving experience (a minimum of 120 hours), on all types of road and in all types of conditions, prior to gaining their drivers' licence.
Age
Age-related factors are also seen as important. For most young drivers, the attainment of their driving license occurs a time when they are attempting to find their own identity and gain independence from their parents (Engström et al. 2003; Laapotti et al. 2001). At this developmental stage, conformity with perceived social norms is often of great importance, and as a consequence, peer influence is particularly potent (Engström et al. 2003). Research suggests that young drivers experience more pressure from their peers to engage in "risky" and/or illegal driving behaviours than older drivers (Engström et al. 2003). One way peer pressure may impact on driving behaviour is through the influence of passengers, which, as noted previously, has been shown to be a risk factor for crash involvement among young drivers (Cavallo and Triggs 1996; Chen et al. 2000). It has been suggested that the presence of passengers in the car (particularly those who are young and male) may encourage young people to engage in risky driving behaviours, such as speeding or following other vehicles too closely (Chen et al. 2000).
Risk exposure
Another factor that may impact on the high crash rate among young drivers is the type of driving experiences they are exposed to (Cavallo and Triggs 1996; Crettenden and Drummond 1994; Laapotti et al. 2001). While young drivers generally do not drive further than older drivers (Crettenden and Drummond 1994), their lifestyles often expose them to more driving risks than other drivers (Laapotti et al. 2001). For example, young drivers are more likely to drive at night or on weekends, when crash rates are higher (Cavallo and Triggs 1996; Crettenden and Drummond 1994; Laapotti et al. 2001). Furthermore, young drivers tend to drive older vehicles, placing them at increased risk of serious injury if they are involved in a crash (Engström et al. 2003).
Risk-taking
Risk-taking has also been implicated in the over-representation of young drivers in traffic accidents. As Williams (1998: 21) notes: "Compared with older people, young drivers are more likely to drive fast, follow too closely, overtake in a risky manner, allow too little time to merge, and fail to yield to pedestrians." However, it would appear that the majority of young drivers who engage in risky driving behaviour do not do so deliberately. Rather, inexperience and a tendency to underestimate risk and overestimate one's own abilities is seen as being responsible for this type of driving behaviour in most of these young drivers (Cavallo and Triggs 1996; Williams 1998). Nevertheless, there is a small sub-group of young drivers for whom such risky driving behaviour appears to be intentional (Williams 1998). The characteristics of this group will now be discussed.
Young problem drivers
In the research focusing on young drivers, much attention has been paid to a small sub-group of "young problem drivers" who are excessive risk takers and deliberately engage in high-risk driving behaviours for the "thrill" they receive from them (Cavallo and Triggs 1996; Crettenden and Drummond 1994; Williams 1998). These drivers are seen as being at increased risk of being involved in a crash, and hence are perceived as an obvious target for interventions aimed at reducing crashes among young drivers (Crettenden and Drummond 1994; Williams 1998).
A wide range of characteristics have been associated with this group of young problem drivers (Cavallo and Triggs 1996; Crettenden and Drummond 1994). These include: high levels of aggression or hostility (Begg et al. 2003; Cavallo and Triggs 1996; Norris et al. 2000; Ulleberg and Rundmo 2003); attentional difficulties (Barkley et al. 2002; Woodward et al. 2000); high alcohol, marijuana and other drug use (Cavallo and Triggs 1996; Lang et al. 1996; Shope et al. 1997; Shope et al. 1996; Shope et al. 2001); a sensation-seeking personality style (Cavallo and Triggs 1996; Jonah 1997; Ulleberg and Rundmo 2003); attitudes favourable to "norm-defying" behaviours (Cavallo and Triggs 1996; Ulleberg and Rundmo 2000); low parental supervision (Hartos et al. 2000; Shope et al. 2001); lenient parental attitudes towards young people's alcohol use (Shope et al. 1996; Shope et al. 1997; Shope et al. 2001); limited/non-existent parent-imposed driving restrictions (Beck et al. 2001; Hartos et al. 2000); and high involvement with peers who misuse substances (Lang et al. 1996; Shope et al. 1996; Shope et al. 1997; Shope et al. 2001).
Additionally, those who engage in high risk driving behaviour are often found to engage in a range of other risky or problematic behaviours (Cavallo and Triggs 1996; Williams 1998), leading to the suggestion that high risk driving behaviour is just one part of a broader problem behaviour syndrome (Williams 1998). This view is consistent with Problem Behaviour Theory (Jessor and Jessor 1977; Jessor 1987), which posits that problem behaviours are not isolated events, but are interrelated and reflect a general underlying trait. Hence, according to this view, risky driving represents just one component of a more general problematic lifestyle (Crettenden and Drummond 1994; Williams 1998).
ATP Young Drivers Study
As is clear from the above review, much of the road safety literature is concerned with documenting the driving behaviour of young adults (for example, their crash and traffic violation rates) and distinguishing risky drivers from other drivers on the basis of their attributes or behaviour at the time at which these crashes or violations occur. Since much of the research conducted to date has been cross-sectional, or covered restricted time spans, there is limited knowledge about the long-term (or "early") social, educational and behavioural precursors of unsafe driving behaviours among new drivers (Engström et al. 2003; Williams 1999).
Longitudinal studies provide an opportunity to better understand how differing driving styles develop and, in turn, assist policymakers and practitioners to identify intervention opportunities (Williams 1999). While some promising longitudinal research has been conducted into the development of problematic driving behaviour (see, for example, Caspi et al. 1997; Fergusson and Horwood 2001; Norris et al. 2000; Shope et al. 1997), longitudinal research in this area is limited. Furthermore, this research has generally been conducted outside Australia, making its applicability to the Australian context uncertain. For example, variations in the age at which driving licences may be legally obtained, and the age at which alcohol use is officially permitted, as well as cultural attitudes and values, may lessen the applicability of studies conducted outside Australia.
The ATP Young Drivers Study attempted to address this research deficit by using data from the longitudinal Australian Temperament Project (ATP) to explore the individual and environmental precursors of differing patterns of young driver behaviour. Drawing upon the expertise of the RACV and the TAC on road safety and driver education issues, the ATP dataset was examined in order to: identify risk factors linked to subsequent patterns of young adult driving behaviour; identify social and behavioural predictors of crash involvement and traffic violations among young drivers; and examine similarities between the profiles of "unsafe drivers" and those who demonstrate other "high risk" behaviours (for example, antisocial behaviour and substance use). In addition, young adults' current driving behaviours and learner driver experiences were also examined.
It is hoped that this research will provide insights into the development of both "normal" and "problematic" driving behaviour among young drivers, which in turn can be used to inform road safety, education and prevention efforts within Victoria.
Structure of the report
The report begins with a brief description of the Australian Temperament Project, the measures used to assess learner driver experiences and young adult driving behaviour, and the measures contained in the longitudinal data set. This is followed by sections examining: the learner driver experiences and current driving behaviour of ATP participants; the longitudinal precursors of differing patterns of unsafe or unlawful driving behaviours ("risky" driving, crash involvement and speeding violations); and the association between "problem" driving behaviour and other problem behaviours (namely substance use and antisocial behaviour). The report concludes with a discussion of the theoretical and practical implications emerging from these findings.