ITARDA

Institute for Traffic Accident
Research and Data Analysis（財）交通事故総合分析センター
ITARDA INFORMATION

93

No.

2012

Driving speeds are

FEBRUARY

higherDriving speeds when
accidents occurred

Front seat passenger age
12 or under

/h

m
50k
Over 70/hwhen both the driver andfront seat passenger are
young than for othersituations
13~17

m
40k

/h

m
30k

/h

m
20k

/h

m
10k

18~29

60~69

Driver age■ 18~29■ 30~39■ 40~49■ 50~59■ 60~69■ Over70

50~59

30~39

40~49

Special feature

Watch out for this whengiving people lifts in your car

Institute for Traffic Accident Research and Data Analysis

ITARDA
INFORMATION
財団法人 交通事故総合分析センター

イタルダ・インフォメーション

2012 FEBRUARY

93

No.

若者同士で乗っていると運転速度が他より事故を起こしたとき
の運転速度

高い

前席同乗者の年齢層
12 歳以下/hm
50k
70 歳以上12 〜 17 歳

/h

m
40k

m/h
30k
/h

m
20k

/h

m
10k

18 〜 29 歳

60 〜 69 歳

運転者の年齢50 〜 59 歳

30 〜 39 歳■ 18〜29歳■ 30〜39歳■ 40〜49歳■ 50〜59歳■ 60〜69歳■ 70歳以上

40 〜 49 歳

Special feature

Watch out for thiswhen giving people
lifts in your car
Many people tend to drive differently when
there are passengers present. In general, it isusual for people to drive more carefully insuch situations, but it appears that there arealso those who tend to push their driving
beyond sensible limits when a passenger ispresent, eager to “show that I’m good atdriving.”
In this issue of ITARDA Information, we lookat the influence which the presence ofpassengers (particularly front seatpassengers) has on driver behavior, andpresent the results of our analysis of suchinfluence, broken down by the ages of bothparties and the relationship between theirages.
Results were obtained using accident datacompiled over a 10-year period from 2001 to
2010, targeting four-wheeled vehicle with anempty vehicle weight of less than 2t, in order
to exclude buses and large trucks.

CONTENTS

1 Number of drivers in accidents with apassenger present

2 Is it safer to have passengers present?
3 Who most often gives lifts to whom?
4 Variation in the driver fatality and serious
injury rate due to drivers’ and front seatpassengers’ ages

5 Influence of front seat passengers
on driver behavior

6 In closing

特集

車に人を乗せるときは、
こんなことにも注意を

Number of drivers in accidents
with a passenger present

CTION
SE

1

How many accidents occur when there arepassengers in a car? Table 1 shows the numberof drivers who have experienced accidents,
broken down by the presence of passengers ineither the front seat or rear seat, and Fig. 1
shows this as a percentage of all accidents.
Drivers who experienced accidents when there

were passengers in the car make up 17.0% of all
drivers aged 50~59 years who experience
accidents, but the figure rises to 21.7% fordrivers aged over 70 years and 21.5% for drivers
aged 18~29 years; the percentage thus varies
according to the age of the driver.

Table 1: No. of drivers in accidents by driver age and presence of passengers(combined figures for primary and secondary parties)(People)Driver age

18~29

30~39

40~49

50~59

60~69

Total accidents

31087822453296

1874365

1938988128642963746111299321

Passenger absent

2441394

193544515148191608501

1041425

4990259040609

Passenger present*

6673885178513595463304872450041384362258712Passenger
presence

Over 70

Total*Either front seat or rear seat passengers

Percentage of drivers with passengers
out of all drivers in accidents

25

20

21.5%

21.7%

21.1%
19.2%

19.0%
17.0%

15

10

5

0

18~29

30~39

40~49

50~59

60~69

Over 70

Driver age

Fig. 1: Percentage of drivers with passengers out of all drivers in accidents

93 ITARDA INFORMATION

3

特集

車に人を乗せるときは、
こんなことにも注意を

CTION
SE

2

Is it safer to have passengers present?

We calculated the “driver fatality and serious
injury rate,” being the rate of fatalities andserious injuries for drivers in their respective
cars, broken down according to whether there
was a passenger present at the time, and set
out the results in Fig. 2.
(No. of driver fatalities+ No. of serious
injuries to drivers)

Driver fatality
and serious=
injury rate (%)

when there are passengers present than when
they are absent. In other words, it is believed thatdrivers put more effort into careful driving when
there are passengers present. These results
show the same trends that were evident in the
results of ITARDA Information No. 77, “The risk of
causing accidents is lower when passengers arepresent.”
With the exception of drivers aged 18~29 years,
it is evident that the driver fatality and serious
injury rate grows higher as driver age rises. The
main reason for this is believed to be that thehuman body’s ability to withstand shocks
declines with advancing age. The reason for thehigh driver fatality and serious injury rate fordrivers aged 18~29 is believed to be that, as isoften pointed out, there are a fair number ofreckless drivers in this age group.

× 100

No. of driver casualties

As the formula indicates, this is the number ofmajor accidents resulting not just in slight
injuries but in fatalities or serious injuries, as apercentage of all accidents.
Fig. 2 indicates that the driver fatality and serious
injury rate is unrelated to driver age, and is lower

12■ Passenger absent

11.1%■ Passenger present

Driver fatality and serious injury rate (%)

10

8.6%

8

6
5.3%
4

2.5%

2

18~29

2.9%

2.8%

2.5%
1.7%

0

4.0%

3.9%

3.6%

30~39

2.2%

40~49

50~59

60~69

Driver age

Fig. 2: Driver fatality and serious injury rate, by passenger presence

4

ITARDA INFORMATION 93

Over 70

CTIONSE

Who most often gives lifts to whom?

3

Up until now, the discussion has concerned
passengers in either the front or rear seatregardless of whether they themselves are
injured or not. From this point, however, we willturn our attention to front seat passengers, whoare believed to exert a particularly strong
influence on driver behavior, and among theseon those front seat passengers who are killed or
injured in accidents.
Table 2 and Fig. 3 show the numbers of drivers
who have experienced accidents, broken down
by mutual age relationship. From this it can beseen that in the bulk of accidents in which afront seat passenger was present, the driver andfront seat passenger were of the same agegroup (the sections highlighted in pink in Table2), a trend that was particularly marked among
young drivers aged 18~29 and elderly drivers
aged over 70 (in Fig. 3, the percentage of total
accidents in which the driver and front seatpassenger were of the same age group was
70% in the case of drivers aged 18~29, and
60% in the case of drivers aged over 70).

Table 2: No. of drivers in accidents by mutual age relationship between driver and front seatpassenger (combined figures for primary and secondary parties)

No. of drivers in accidents where a front seat passenger
was present, of all drivers in accidents (10,000 people)

Driver

Front seatpassenger 12 or under(People)

13~17

18~29

30~39

40~49

50~59

60~69

Over 70

18~29

13888

11639

215994

27731

13298

19971

4163

2380

30~39

34445

6430

41027

82302

17113

12888

14046

3217

40~49

13730

19248

19912

22960

41584

12938

7423

9361

50~59

2843

3915

19312

9214

18952

53052

13545

11053

60~69

2373

853

3365

6111

3640

22666

46239

10238

Over 70

683

756

620

757

1389

1840

16308

33747

25
Front seatpassenger age

70%■ 12 or under20■ 13~17■ 18~29■ 30~39■ 40~49■ 50~59■ 60~69

15■ Over 70

10

39%
28%

5

0

40%

48%
60%

18~29

30~39

40~49

50~59

60~69

Over 70

Driver age

Fig. 3: No. of drivers in accidents by mutual age relationshipbetween driver and front seat passenger
93 ITARDA INFORMATION

5

特集

車に人を乗せるときは、
こんなことにも注意を

CTION
SE

4

Variation in the driver fatality andserious injury rate due to drivers’ andfront seat passengers’ ages

Fig. 4 shows the driver fatality and serious injury
rate by mutual age relationship between thedriver and front seat passenger.
As with the results of Fig. 2, it is evident that thedriver fatality and serious injury rate grows
noticeably higher as the driver age rises.
Looking at Fig. 4, another striking point may beobserved. The driver fatality and serious injury
rate is extremely high when the driver is aged
18~29 and the front seat passenger is aged
13~17.
Let us consider the reasons for this, in terms ofdriver behavior, and specifically in terms ofdriving speed and the seat belt use situation.

CTION
SE

5

Over 70

12%

10%

13~17

Driver age■ 18~29■ 30~39■ 40~49■ 50~598%■ 60~69

6%■ Over70

4%
2%
0%

60~69

50~59

18~29

30~39
40~49

Fig. 4: Driver fatality and serious injury rate,by mutual age relationship between
the driver and front seat passenger

Influence of front seat passengers
on driver behavior
When young people are in the car
together, the danger perception speed
is higher than for other situations(1) Influence on driving speed at the time of accidents
The “danger perception level”—that is, the speed
at which the driver perceives the danger of an
accident—is set out in Fig. 5, broken down by
mutual age relationship between the driver andfront seat passengers.
When drivers aged 18~29 gave lifts in the front
seat to passengers their own age or slightly
younger—that is to say, front seat passengers
aged 13~17 or 18~29—it is evident that the
speed at which they drove was more than
5~10km higher than with other front seatpassengers. It may be surmised that drivers are
apt to feel a sense of exhilaration when they arewith other young people, and a consciousnessof wanting to “adopt a cool pose.” By contrast,
the driving speeds of drivers in age groups
other than 18~29 clustered around the 30km/h
range, regardless of the age of the front seatpassenger.
6

Fatality and
12 or under serious injury
14%
rate (%)

Front seatpassenger age

ITARDA INFORMATION 93

Front seatpassenger age

Over 70
Driving speed(km/h)

12 or under

Driver age

50km/h
40km/h

13~1730km/h■ 18~29■ 30~39■ 40~49■ 50~59■ 60~69

20km/h■ Over70

10km/h

60~69

18~29

50~59

30~39
40~49

Fig. 5: Driving speeds when accidents occurredWhen young people are in
the car together, the seatbelt use rate is lower(2) Influence on the seat belt use rate
Next, in Fig. 6 we set out the seat belt use
situation for drivers when they experienced
accidents. The seat belt use rate for drivers aged
18~29 is noticeably lower when the front seatpassenger is aged 13~17; even when the front
seat passenger is aged 18~29, 12 or under, or
30~39, the rate is still lower than the rates forfront seat passengers in other age groups.
Predictably, drivers feel less on their guard whendriving if their passengers were also young(although the effects in the case of rear seatpassengers are unknown).

Front seatpassenger age

Over 70
Seat belt use rate (%)

12 or under

Driver age■ 18~29■ 30~39■ 40~49■ 50~59■ 60~69■ Over70

100%
90%

13~17

80%
70%

60~69

18~29

60%

50~59

30~39
40~49

Fig. 6: Seat belt use rate of drivers

Meanwhile, the seat belt use situation for front
seat passengers is set out in Fig. 7, where it isevident that the seat belt use rate for front seatpassengers like that for the drivers is low whenboth drivers and front seat passengers areyoung. It would appear that both parties arehaving bad influences on each other in somemanner.
Let us look once again at Fig. 7. One notices
that the seat belt use rate is lowest whenchildren aged 12 or under occupy the front seat(in this instant, seat belt includes child seats (forinfants, for young children, for school-aged
children etc.)). This trend is most strongly
evident when drivers are aged 50~59, 60~69 orover 70—in other words, when children areoccasionally given lif ts by people who are
generally believed to give lifts to children on an
infrequent basis (grandparents andgrandchildren etc.). Strictly speaking, children
should be required to sit in the rear seat, but it
appears that this rule is not being adhered tostrictly. Another reason is considered to be thatpeople in these age groups are not always able
to prepare a child seat.

Front seatpassenger age

The seat belt use rate
is lowest for children
aged 12 or under
12 or under
100%

Over 70
Seat belt use rate (%)

90%

13~17

80%

Driver age■ 18~29■ 30~39■ 40~49■ 50~59■ 60~69■ Over70

70%

60~69

18~29

60%

50~59

30~39
40~49

Fig. 7: Seat belt use rate of front seat passengers

93 ITARDA INFORMATION

7

Institute for Traffic Accident Research and Data Analysis

ITARDA INFORMATION

特集

車に人を乗せるときは、
こんなことにも注意を

CTION
SE

6

In closing

イタルダ・インフォメーション❶ Message for young drivers
When young drivers give lifts to other young passengers in the front
seat, it appears that they pay insufficient attention to safety, often
driving at excessive speeds and not wearing seat belts. Young drivers
may want to adopt a cool pose, but the tragedy is that causing an
accident and injuring a passenger is the least “cool” thing anyone
can do. We urge young drivers to pay particular attention to safe
driving precisely at those times when they have passengers, take theinitiative in fastening their own seat belts, and encourage their  passengers to fasten theirs as well.

❷ Message for elderly drivers

93

No.

発 行 （財）交通事故総合分析センター
発行月 平成 年 月 〒102 0083 東京都千代田区麹町6 6 麹町東急ビル 階

We urge elderly drivers to cease the careless practice of allowing
grandchildren and other children to travel in the front seat of the car.
It is safer for children aged 12 or under to travel in the rear seat. Even
when travelling in the rear seat, young children under the age of 6 arerequired to use a child seat; even for children over the age of 6, useof a junior seat or booster seat suited to a child’s physicalrequirements is recommended until the age of 12.

2012

FEBRUARY

24
2

-

-

5

(Creator: Shinichi Yoshida)
事務局〒102-0083 東京都千代田区麹町6-6 麹町東急ビル5階
TEL03-3515-2525 FAX03-3515-2519

つくば交通事故調査事務所〒305-0831 茨城県つくば市西大橋6 41-1
（財）日本自動車研究所内
TEL029-855-9021 FAX029-855-9131