Safety Science 44 (2006) 75–85

www.elsevier.com/locate/ssci

First year as a licensed car driver: Gender diVerencesin crash experience

Joel Monárrez-Espino ¤, Marie Hasselberg, Lucie LaXamme

Department of Public Health Sciences, Division of Social Medicine, Karolinska Institutet, Norrbacka Huset,SE-171 76 Stockholm, Sweden

Received 15 February 2005; received in revised form 26 June 2005; accepted 13 July 2005

Abstract

Objective: To explore the crash experience and crash consequences of newly licensed male andfemale drivers aged 18–29 years.

Methodology: A national register-based population cohort of persons born between 1970 and1972 was followed for the period 1988–2000 on the basis of crash data in Swedish police records. Theanalyses focused on two crash categories regardless of consequences: single car (SC) and car-to-motor vehicle (CMV).

Results: Crash incidence for men was nearly double that of women in all age groups in both crashcategories. Age had a protective eVect for both sexes, especially for SC crashes. Males, but notfemales, showed a lag in time from driving license issue date to Wrst crash for SC crashes, whichincreased with age of obtaining a license. Men’s crash fatality rate was Wve times higher than that ofwomen for SC crashes (32.2 and 6.1 per 1000, respectively), but the rate was comparable for CMVcrashes (16.1 and 15.7, respectively). The crash morbidity rate was 25–30% higher for male drivers inboth crash categories.

Conclusions: Both young age and male sex emerge as important determinants of crash risk andcrash consequences among young Swedish drivers. 2005 Elsevier Ltd. All rights reserved.

Keywords: Gender diVerences; Crash incidence; Road-traYc injuries; Young drivers

* Corresponding author. Tel.: +46 8 7373776; fax: +46 8 7373878.E-mail address: joel.monarrez@kbh.uu.se (J. Monárrez-Espino).

0925-7535/$ - see front matter 2005 Elsevier Ltd. All rights reserved.doi:10.1016/j.ssci.2005.07.004

76 J. Monárrez-Espino et al. / Safety Science 44 (2006) 75–85

1. Introduction

Road traYc injuries (RTIs) are the leading cause of death among people aged 15–29 years in high-income European countries (Peden et al., 2002). Also, studies have consis-tently shown that young drivers have a higher risk of being involved in a road traYc colli-sion than other drivers (Williams, 2003). As explanations, among others, for the highercrash risk of young drivers, two closely related but independent factors have been investi-gated: driving inexperience and young age (a marker of adoption of risky behaviours)(Arnett, 2002; Ballesteros and Dischinger, 2002; Catchpole et al., 1994; Gregersen et al.,2000; Laberge-Nadeau et al., 1992; Levy, 1990; Mayhew and Simpson, 1990; Mayhew,2003; Preusser and Leaf, 2003; Turner et al., 2004; Waller et al., 2001; Williams, 2003).DiVerences between male and female drivers of comparable age were also considered, andthere is persuasive evidence that being a male car driver elevates crash risk (Åkerstedt andKecklund, 2001; Ballesteros and Dischinger, 2002; Hasselberg et al., 2005; Laberge-Nadeau et al., 1992; LaXamme and Engström, 2002; LaXamme et al., 2005; Massie et al.,1995; Turner et al., 2004; Waller et al., 2001; Williams, 2003), especially so in the case ofsevere crashes (Ballesteros and Dischinger, 2002; Massie et al., 1995; Massie et al., 1997;Waller et al., 2001; Williams, 2003).

Over the past decade, the eVects of driving inexperience, youth, and gender on crash riskhave become a major research topic. The aim of related studies is often to increase knowl-edge of how these three factors interact so as to pave the way for modiWcations in drivingeducation systems and licensing mechanisms that might neutralize potentially harmfuleVects.

Several studies have reported that the risk of collision decreases as young driver experi-ence increases, measured either as time from obtaining a driving license or as cumulativedistance driven (Jiménez-Moleón et al., 2004; McCartt et al., 2003; Preusser and Leaf,2003; Waller et al., 2001; Williams, 2003). Others have looked at the modifying eVect ofgender on the relationship between the risk of being actively involved in a road traYc acci-dent (RTA) and time of obtaining a driving license. The Wndings have been contradictory;whereas Waller et al. (2001) found a faster declining risk of RTA per year after obtaining alicense among women, Jiménez-Moleón and colleagues (2004) reported a more pro-nounced decrease in risk with increasing number of years in possession of a driving licensefor men. Yet, little is known regarding the eVect of age (i.e. drivers’ overall maturity) on thediVerential risk of crashing between young male and female drivers with similar drivingexperience.

The current study builds on previous results and investigates gender and crash speciWcrisk diVerences in crash involvement, during the Wrst year following licensing and betweenages 18–29 years. Two very common categories of collisions among young drivers are con-sidered: single car (SC) and car-to-motor vehicle (CMV). The following study questionsare considered:

• Does crash involvement diVer between male and female drivers during their Wrst year asa license holder?

• Does time elapsing from driving license issue date to Wrst crash during the Wrst drivingyear diVer between male and female drivers? Does it diVer according to age at licensing?

• What are the diVerences in crash morbidity and mortality rates during the Wrst year ofdriving between male and female drivers?

J. Monárrez-Espino et al. / Safety Science 44 (2006) 75–85 77

2. Methodology

2.1. Study design

The study group consists of a register-based population cohort of persons born betweenJanuary 1st 1970 and December 31st 1972. The cohort was based on the Swedish popula-tion and housing census (SPHC) of 1985 (n D 336426). Age at obtaining a driving licensewas obtained from the National Driver’s Licence Registry in 2001, which is administeredby the Swedish National Road Administration (SNRA). The register was used to calculatethe time between obtaining the driver license and the Wrst crash.

Licensing age for car driving in Sweden is 18 years, and in 1988, at the beginning of thefollow-up period, about 50% of the 18 years olds had a driving license and at the age of 19,about 72% had.

Individual records were linked to road traYc crash data for the period 1988–2000 froma register, held by the SNRA, that contains police reports on car crashes. Record linkagewas achieved using the unique personal identiWcation number assigned to all residents ofSweden.

The police register was used to identify the person’s Wrst recorded crash as car driver.The study focused solely on crashes that occurred within the Wrst year of drivers havingobtained a driving license; the analyses were limited to SC and CMV crashes, but weretreated regardless of consequences (injury severity). These two types of collisions accountfor nearly three-quarters of total registered crashes.

According to police data, a total of 31 104 crashes occurred between 1988 and 2000. Forthe analyses, the following categories were excluded: all crashes that were not the driver’sWrst; crashes of unlicensed drivers and of drivers aged <18 or 730 years at licensing;crashes with a date before driving license issue date; crashes occurring >1 year after thedriving license was issued; crashes involving other than a personal vehicle/car (i.e. moped,motorcycle, bus, etc.); crashes where the driver was unharmed; and, crashes of a type otherthan SC or CMV.

2.2. Exposure assessment

Since no information on driving duration, vehicle characteristics, or driving conditionswas available, driving exposure had to be assessed through the drivers’ licensing age. Thiswas used as a proxy for driving debut.

Driving license issue date was obtained from the National Driving License Registry in2001, which is administered by the SNRA. Of the 336426 persons included in the studypopulation, 46933 had not obtained a driving license, 27 014 had received a provisionallicense when aged <18, and 1322 had received one when aged 730 years. Exclusionof these groups left a total of 261 157 persons, which comprised the study population atrisk.

2.3. ClassiWcation of crash consequences

In police records, injuries are divided into three crash-severity categories according toinformation Wlled in on-site by the police, namely, (1) minor injuries, corresponding to nohospital care, (2) severe injuries, corresponding to broken bone, crush injury, gash and

78 J. Monárrez-Espino et al. / Safety Science 44 (2006) 75–85

other serious wound, concussion, internal injury, or injury requiring hospital care, and(3) fatal injuries, corresponding to deaths occurring at the crash location. For the pur-pose of this study, injuries as a result of the crash were assembled into just two groups:(1) severe injuries, and (2) fatal injuries, including deaths occurring within 30 days of thecrash.

2.4. Statistical analyses

The number of crashes per 1000 persons was calculated for male and female driversinvolved in SC and CMV crashes, following stratiWcation by age group. Four age groupswere created: 18.0–18.9; 19.0–19.9; 20.0–22.9; 23.0–29.9.

Cumulative incidence was used because of the low crash frequency, which gives esti-mates almost equivalent to the incidence rates. Also, the idea was to look at the trend byage rather than to provide “exact” Wrst year incidence estimates (in the sense that thedenominator would exclude time after the crash had occurred). Odds ratios (ORs) with95% conWdence intervals (CIs) were computed (Gardner and Altman, 1989) to detect riskdiVerences by age among male and female drivers, using those aged 18–18.9 years as refer-ence group. ORs were used for being the most logical measure when dealing with fre-quency data.

Line graphs were drawn to show cumulative crash incidence rates by sex, age groupat Wrst obtaining a driving license, and time when the crash occurred. Time of crashwas categorized into “working time”, i.e. during weekdays (Monday to Friday) from06:01 to 18:00, and “non-working time”, i.e. weekdays between 18:01 and 06:00 orweekends.

Box-plot graphs (median and quartiles) were used to depict the time elapsing (inmonths) from driving license issue date to Wrst crash, following stratiWcation by drivers’sex, age at Wrst license and type of crash (SC or CMV).

The numbers of persons killed and severely injured resulting from a crash, along withcrash fatality and morbidity rates (per 1000 persons), were calculated by sex and type ofcollision.

Data were entered, linked and analyzed in the SPSS® computer software package, ver-sion 10.1 (SPSS Inc., Chicago, Illinois). The study was approved by the Ethics Committeeat Karolinska Institutet.

3. Results

Table 1 shows diVerences in crash risks for the Wrst year after obtaining a drivinglicense by licensing age for male and female drivers. The cumulative crash involvementincidence rate of males is nearly double that of females for all age group categories orcrash types. CMV crashes accounted for nearly 60–65% of the incidence among bothsexes. Incidence decreases with age, especially among male drivers. This is also reXected inthe ORs, which show a signiWcant protective eVect of age, especially for SC crashes, withthe lowest OR for drivers aged 23–29.9 years (0.34; CI 0.20–0.57).

Cumulative crash incidence rates for the Wrst year after obtaining a driving license bylicensing age, sex, and crash time are plotted in Fig. 1. Overall, incidence tends todecrease with age, except for male drivers who show a clear increase in incidence at 22–23.9 years. For male drivers, the stratiWed analyses by time of crash show that the

J. Monárrez-Espino et al. / Safety Science 44 (2006) 75–85 79

increase in incidence seen in those aged 22–22.9 is largely attributable to crashes occur-ring during working time. Conversely, crashes occurring during non-working timeaccount for the increase risk among those aged 23–23.9 years. Female drivers show amore steady pattern, with risk declining with age, but also with a slight increase in risk atolder ages.

The box plot graphs in Fig. 2 present the crash incidence distribution within the 12-month period of the analyses, following stratiWcation by driver’s sex, licensing age, andtype of crash. For SC crashes, male drivers show a clear lag in time from driving licenseissue date to Wrst crash, which increases with age. For instance, while almost 50% of thoseaged 18–18.4 years crashed during the Wrst four months after obtaining their driver’slicense, only 25% of those aged 23–29.9 years did so during the Wrst six months afterobtaining their license. This trend is also evident among women, except for thoseaged720 years who tend to crash sooner than men. For CMV crashes, no clear trend wasseen for either sex by licensing age, but female drivers were found to crash slightly earlierthan males.

The numbers of persons killed and severely injured following a crash are presented inTable 2. By gender, totals of 22 and 2 deaths were registered for SC crashes, and 17 and 8for CMV crashes, for male and female drivers, respectively. For SC crashes, the crash fatal-ity rate associated with male drivers was 32.2/1000, compared with 6.1/1000 for femaledrivers; however, for CMV crashes the rates were similar, at 16.1 and 15.7, respectively.Among male drivers, 78.9% and 50% of the crashes leading to death occurred during non-working time for SC and CMV crashes, respectively, compared with 56.3% and 62.5% forfemale drivers. Turning to the numbers of severely injured, the crash morbidity rate was25–30% higher among male drivers for both SC and CMV crashes.

Table 1DiVerences in crash risks by age of obtaining a driving license for male and female drivers who crashed in singlecar (SC) and car-to-motor vehicle (CMV) collisions during Wrst year of having a license for the period 1988–2000in Sweden

a Cumulative incidence rate for the whole study period.

Age at license (years)

Crashes Pop. at risk

Rate per 1000a

Odds ratio (95% conWdence interval)

Males [SC/CMV] 1733 [682/1051] 127 963 13.5 [5.3/8.2]18–18.9 [SC/CMV] 1428 [567/861] 98 325 14.5 [5.7/8.7] 1.0 [1.0/1.0]19–19.9 [SC/CMV] 165 [62/103] 12 357 13.3 [5.0/8.3] 0.91 (0.78–1.08) [0.86 (0.66–1.13)/

0.95 (0.77–1.16)]20–22.9 [SC/CMV] 96 [38/58] 9778 9.8 [3.9/5.9] 0.67 (0.54–0.82) [0.67 (0.48–0.93)/

0.67 (0.51–0.88)]23–29.9 [SC/CMV] 44 [15/29] 7503 5.8 [2.0/3.8] 0.40 (0.29–0.54) [0.34 (0.20–0.57)/

0.43 (0.30–0.63)]

Females [SC/CMV]

833 [326/507] 133 194 6.2 [2.4/3.8]

18–18.9 [SC/CMV] 616 [248/368] 88 141 6.9 [2.8/4.2] 1.0 [1.0/1.0]19–19.9 [SC/CMV] 110 [34/76] 18 255 6.0 [1.9/4.1] 0.86 (0.70–1.05) [0.66 (0.46–0.94)/

0.99 (0.77–1.27)]20–22.9 [SC/CMV] 66 [31/35] 14 839 4.4 [2.1/2.3] 0.63 (0.49–0.81) [0.74 (0.51–1.07)/

0.56 (0.39–0.79)]23–29.9 [SC/CMV] 41 [13/28] 11 959 3.4 [1.1/2.3] 0.48 (0.35–0.67) [0.38 (0.22–0.67)/

0.55 (0.38–0.82)]

80 J. Monárrez-Espino et al. / Safety Science 44 (2006) 75–85

4. Discussion

This study was concerned with the crash and gender speciWc eVects of age on the risk ofcrashing a car during Wrst year after licensing among drivers aged 18–29 years.

4.1. Main Wndings

The results show that males have a higher incidence of crash involvement than femalesin all age groups for both SC and CMV collisions. Similar to other Wndings, ORs werefound to decrease with age irrespective of gender of driver (Jiménez-Moleón et al., 2004;Mayhew et al., 2003; Waller et al., 2001).

Fig. 1. Cumulative crash incidence for male and female drivers involved in a car-to-motor vehicle or single crashduring the Wrst year of obtaining a driving license by licensing age and time when the crash occurred, period1988–2000, Sweden.

Working time: Weekdays (Monday to Friday), from 06:01 - 18:00 h

Non-working time: Weekdays, 18:01 - 06:00 h, and all weekends

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

18–18.9 19–19.9 20–20.9 21– 21.9 22–22.9 23–23.9 24–24.9 25–29.9

Age group at first driving license

Cum

ulat

ive

inci

denc

e x

1000

pop

ulat

ion

Total men Working time men

Non-working time men Total women

Working time women Non-working time women

J. Monárrez-Espino et al. / Safety Science 44 (2006) 75–85 81

Also consistent with other studies, our results show a higher incidence among youngerdrivers for SC crashes (Ryan et al., 1998; Ulmer et al., 1997; Zhang et al., 1998). In the caseof CMV crashes, incidence also decreases with age, especially among male drives. Theseresults are in line with earlier Swedish studies revealing consistent excess risks among male

Fig. 2. Box plot graphs depicting time elapsing from obtaining a driving license to Wrst car-to-motor vehicle andsingle crash occurring within the Wrst year of licensing by drivers’ sex and age at Wrst licensing, period 1988–2000,Sweden.

Mon

ths

elap

sed

from

driv

ing

licen

sure

to fi

rst c

rash 12

10

8

6

4

2

0

28357694274 958103188673N =

Driver's age at first driving license by age group in years

23.0–29.920.0–22.919.0–19.918.5–18.918.0–18.4

Mon

thse

laps

ed fr

omdr

ivin

g lic

ensu

re to

first

cras

h 12

10

8

6

4

2

0

Singlecar

crashC

ar-to-motor

vehiclecrash

Male Female

82 J. Monárrez-Espino et al. / Safety Science 44 (2006) 75–85

drivers across types of crashes (including SC and CMV), (Hasselberg et al., 2005) and alsocategories of cars (LaXamme et al., 2005).

Further, we noticed a clear increase in the crash incidence for male drivers aged 22–23.9 years, which we believe to have an occupational component. However, the analysis bytime of crash showed a mixed picture. While the increase for drivers aged 22–22.9 is linkedto crashes occurring during working time, the elevated incidence seen among those aged23–23.9 is related to crashes occurring during non-working hours. The reason for thisincrease needs further investigation.

Further, our results suggest that there might be a change in driving behaviour over timethat is related to type of crash. For instance, by contrast with CMV collisions, where thetime elapsing from driving license issue date to Wrst crash is similarly distributed by sex andage at Wrst obtaining a license, the time distribution for SC crashes shows a lag for Wrstcrash by age among male drivers. Whereas 25% of the crashes among males aged 18–18.4 years took place before the two Wrst months after having obtained a license hadelapsed, the same proportion of crashes occurred within the Wrst six months among thoseaged 23–29.9 years. Female drivers show a similar trend as males up to the age of 20 years,but then time elapsed tends to decrease among the small number of women aged 20 yearsor more when Wrst licensed. These results suggest that drivers tend to be equally cautiousduring the Wrst year when another motor vehicle is involved, irrespective of gender orlicensing age, but that male drivers tend to drive more carefully or less risky as their licens-ing age increases when only their car is involved.

Finally, the consequences of a crash on the driver and others tend to be more severeamong male drivers, in particular in the case of SC crashes. Indeed, the crash fatality ratewas found to be Wve times higher among male than female drivers for SC crashes, althoughsimilar for CMV crashes. Further, the crash morbidity rate is around 25–30% higheramong male drivers for both types of crashes. Thus, not only are men involved in morecrashes, but there are more fatalities when a male driver is involved in the crash. The factthat three out of four deaths from SC crashes are associated with men driving during non-

Table 2Persons killed and severely injured for male and female drivers resulting from car-to-motor vehicle (CMV) orsingle car (SC) crashesa that occurred during the Wrst year after obtaining a driving license, period 1988–2000,Sweden

a Involving drivers who obtained their license when aged 18–29 years.b The numbers in parentheses refers to the number of crashes within each category.

Category Male Female

SC CMV Total SC CMV Total

Persons killed in the crashb

None 662 1035 1697 324 499 823One 18 15 33 2 8 10Two 4 (2) 2 (1) 6 (3) 0 0 0Crash fatality rate per 1000 32.2 16.1 22.9 6.1 15.7 12.1

Persons severely injured in the crashb

None 473 852 1325 237 416 653One 150 127 277 73 67 140Two 78 (39) 90 (45) 168 (84) 28 (14) 36 (18) 64 (32)Three or more 68 (20) 99 (27) 167 (47) 35 (2) 56 (6) 91 (8)Crash morbidity rate per 1000 434.0 306.3 353.1 331.2 242.6 277.3

J. Monárrez-Espino et al. / Safety Science 44 (2006) 75–85 83

working hours who had obtained their license before the age of 20 highlights the impor-tance of targeting preventive eVorts at young men during their driving education.

4.2. Study limitations

An important methodological limitation of the study lies in the form in which exposureto car driving was measured. We had to rely upon the driver’s licensing age as a surrogatefor unsupervised driving debut, and thus assumed a similar driving exposure within andbetween ages and sexes. As a consequence, our Wndings might reXect a diVerence not onlyin vulnerability (or behaviour), but also a quantitative one in terms of exposure time orkilometres driven between male and female drivers at diVerent ages (which are major deter-minants of experience) (Ballesteros and Dischinger, 2002; Catchpole et al., 1994; Dohertyet al., 1998). Moreover, no data at all were available regarding time exposed to superviseddriving, which may have varied substantially by age and gender, thereby aVecting driver’sexperience and consequently the risk of crashing.

On the other hand, the study base can be considered as representative at national level,since the rate of missing cases in the SPHS was only 0.8% (Statistics Sweden, 1989).

As the study was designed to focus on two categories of crash involvement rather thanan aggregation of all crashes, direct comparisons with other studies are restricted. Also, thestudy focused only on SC and CMV collisions that occurred during the Wrst year afterobtaining a driving license. Nor did the study consider driver’s responsibility for crashing,which has been found to be associated with driving inexperience (Cooper et al., 1995).

From another point of view, the study is silent regarding the reasons behind the diVer-ences observed between age groups. In the Swedish context, licensing is allowed at the ageof 18 and an important proportion of young people do get a driving license at that age.Because of that, the results are a better reXection of lack of experience than one of theoften-entangled eVect of general inexperience and lack of maturity that is common to mostvery young driver.

Nevertheless, the study does not sort out and address possible diVerences within agegroups—and at same age of obtaining a driving license—based on e.g., socio-demographicfactors. Neither does it shed light on diVerences between age groups that may have to dowith other factors than age at obtaining a driving license and may help understandingsome of the diVerences observed.

4.3. Implications for prevention

Driving is a means of transportation that can be discussed from various angles, e.g.,environmental, individual mobility, and safety. Thus, safety is only one of the issues, whichcan sometimes conXict with others. Sweden is a country where traYc injury rates are rela-tively low, where the licensing age is rather high (18 years) compared with many countries,and where driver training is conceptualised in such a way that experience accumulatesgradually. Despite all this, during the Wrst year after licensing, male drivers remain a groupof central concern with regard to crash-related injuries (to themselves and to others).

That driving inexperience can only be overcome by more driving, leading to additionalexposure with a subsequent increase in crash risks (Simons-Morton, 2002) does remain adilemma. In the particular case of Sweden, since the rate of crash leading to injury is notlarge in absolute terms, there may be no reason to try and tackle the problem through

84 J. Monárrez-Espino et al. / Safety Science 44 (2006) 75–85

additional limiting options, such as driving postponement or driving restriction. Also, itought to be kept in mind that regulations of the like may have more negative eVects onsome socio-demographic groups than other (for instance because of their geographicallocation or the need that they have of a car) and thereby introduce unnecessary and unde-sirable discriminating barriers.

5. Conclusion

Both licensing age and sex emerge as important determinants of crash risk and crashconsequences during the Wrst driving year among young car drivers in Sweden. Althoughthe OR for crash involvement decreased with age irrespective of drivers’ sex for both singleand motor-vehicle crashes, we observed a lag between obtaining a driving license and Wrstcrash for SC crashes among male drivers, which suggests that there is a tendency to drivemore carefully as licensing age increases.

The eVect of licensing age was also evident for male drivers involved in single crashes,who showed a Wve-fold higher crash fatality rate than female drivers. In fact, 75% of all SC-related deaths were associated with men driving during non-working time who hadobtained their license before the age of 20 years.

The share of young driving men in the crash and mortality rates shown in this studymay be an important challenge for the Swedish driving education system.

Acknowledgement

This study was Wnanced by the Swedish National Road Administration.

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