イタルダ インフォメーション

ITARDA INFORMATION
交通事故分析レポート No.131lSpeciafeatureAre elementary school students being
made to wear their seatbelts properly?
~ Protecting elementary school student
passengers in cars from accidents ~(Passengers in front and rear seats inmedium and kei passenger cars only)

140

The degree of decline for elementary
school students is small!

120

Index

100
80
60
40
20

6-12 years

20-64 years

n＝177,584

0Over 64 years

n＝1,366,274

n＝287,684

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

Fig. 1. Trend in number of casualties for passengers
per 100,000 population by age group(With number of casualties per 100,000 populationin 2001 set as 100)

1 Introduction ・
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Problem of many seatbelt non-use cases in rear seats
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2 among elementary school students
3 Even in seatbelt use cases, eﬀects of seatbelt use are sometimes ・・・P5
not being suﬃciently obtained among elementary school students
4 Why eﬀects of seatbelt use are not being suﬃciently obtained ・
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among elementary school students
5 Conclusion ・
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SpeciafeatureAre elementary school students being made to wear their seatbelts properly?
~ Protecting elementary school student passengers in cars from accidents ~1 Introduction
The number of casualties resulting from traffic accidents that occurred in 2018 was 529,378. In the 10th Traffic
Safety Basic Plan, the Japanese government has set forth a goal of reducing the annual number of casualties tobelow 500,000 by 2020, and has been carrying out various measures in this regard. Pedestrians, children, andelderly persons, or so-called “vulnerable road users,” account for high percentage of the casualties, and as such,
focused initiatives for these groups are needed. How are various initiatives changing the numbers of casualties
from traffic accidents among children and elderly persons?
Fig. 1 on the cover page shows the trend in the number of casualties per 100,000 population1) for passengers infront and rear seats in medium and kei passenger cars (primary and secondary-party cars directly involved intraffic accidents) by age group. It appears that in all age groups, various measures have been effective incontinuously decreasing the number of casualties.
Meanwhile, in the case of passengers of age 6 to 12 years, the degree of decline in the number of casualties per
100,000 population has been smaller than that of other age groups, and thus the trend of decline appears to differ
from one age group to another. Similarly, in Fig. 2, which shows the trend in the number of fatalities or serious
injuries, it can be seen that in the case of the number of fatalities or serious injuries per 100,000 population, thedegree of decline among passengers of age 6 to 12 years is on par with that of elderly persons, and less than thatof 20 to 64 years. Thus, it seems that measures to protect passengers of age 6 to 12 years from traffic accidents
have been slow to take effect compared to those for other age groups. What makes this group different from otherage groups?
120(Passengers in front and rear seats in medium and kei passenger cars only)

100

Index

80
60
40
20
6-12 years

20-64 years

n＝2,6950Over 64 years

n＝38,248

n＝23,639

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

Fig. 2. Trend in number of fatalities or serious injuries
for passengers per 100,000 population by age group(With number of fatalities or serious injuries per 100,000 population in 2001 set as 100)

Since most 6 to 12-year-old children are elementary school students, passengers of age 6 to 12 years are
hereinafter referred to as “elementary school students,” and analysis is carried out placing a focus on accidents
involving this group of passengers. Furthermore, since use/non-use of seatbelt is deeply related to whether injuries
were sustained and the seriousness of injuries sustained during accidents, consideration will be given to thecharacteristics of, and issues related to fatality or serious injury accidents by use/non-use of seatbelt, andelementary school students will be compared with 20 to 64-year-old non-elderly adults (hereinafter “adults”) in thecontext of such accidents.

Problem of many “seatbelt non-use” cases in
2 rear seats among elementary school students■ Status of seatbelt use among elementary school students
Let us first of all take a look at the status of seatbelt use with regard to fatalities or serious injuries among
elementary school students.
Table 1 shows: Ⓐ the riding ratio in front passenger seat and rear seat, Ⓑ the rate of seatbelt non-use by front
passenger seat and rear seat, and Ⓒ the rate of seatbelt non-use by front passenger seat and rear seat according
to the riding ratio, in 2001 through 2018. The definitions of these are as follows.
ITARDA INFORMATION no.131

ITARDA INFORMATION no.131Ⓐ Riding ratio = number of fatalities or serious injuries in front passenger seats versus number of fatalities orserious injuries in rear seatsⒷ Rate of seatbelt non-use by front passenger seat and rear seat (%)= number of fatalities or serious injuries in “seatbelt non-use” cases in relevant seat ÷ number offatalities or serious injuries in relevant seat × 100Ⓒ Rate of seatbelt non-use by front passenger seat and rear seat according to riding ratio (%)= Ⓐ × Ⓑ = number of fatalities or serious injuries in “seatbelt non-use” cases in relevant seat÷ number of fatalities or serious injuries in all passenger seats × 100(This calculation is based on the number of fatalities or serious injuries and thus differsfrom the actual riding ratios and rate of seatbelt non-use.)

Table 1. Rate of seatbelt non-use during accidents
in medium and kei passenger cars
Ⓑ Rate of seatbelt non-use
by front passenger seatand rear seat

Ⓐ Riding ratio
Elementary
schoolstudents(Based on total number of fatalities
or serious injuries in 2001 through 2018)Ⓒ Rate of seatbelt non-use by
front passenger seat and rear seataccording to riding ratio (Ⓐ × Ⓑ)

versus71
29％ ％versus71
27％ ％versus

38
62％ ％

74
18％ ％

28
11％ ％

8％

50
％

(6-12 years)

Adultsversus(20-64 years)

versusversusⒶ in Table 1 shows that a higher ratio of elementary school students were riding in rear seats than front passenger
seats (71% versus 29%). Ⓑ shows that the rates of seatbelt non-use in rear seats were about the same forelementary school students and adults, at roughly 70%.
As is shown in Ⓒ, while the rates of seatbelt non-use in rear seats were about the same for elementary school
students and adults when an elementary school student was riding in the car, because it was more common forelementary school students to ride in rear seats, elementary school students accounted for a significantly higher
percentage of cases for seatbelt non-use in rear seats (50%) than adults (28%).
■ Trend in number of fatalities or serious injuries in “seatbelt non-use” cases per 100,000

population when elementary school students were riding in “rear seats”

As such, it has been shown that elementary school student passengers account for “a high rate of seatbelt
non-use cases in rear seats.” Thus, we will next take a look at the trend in the number of fatalities or serious
injuries in “seatbelt non-use” cases per 100,000 population when the passenger is riding in a “rear seat.” Fig. 3
shows the trend by front passenger seat and rear seat in and after 2001.
140(Passengers in front and rear seats in medium and kei passenger cars only)120

The degree of decline for “seatbelt non-use”
cases when elementary school students areriding in “rear seats” is small!

Index

100
80
60
40
20
0

6-12 years, front passenger seat, n＝213
20-64 years, front passenger seat, n＝4,361
6-12 years, rear seat, n＝1,358
20-64 years, rear seat, n＝10,713
2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

Fig. 3. Trend in number of fatalities or serious injuries in “seatbelt non-use” cases per 100,000 populationfor elementary school students and adults by front passenger seat and rear seat
(With number of fatalities or serious injuries per 100,000 population in 2001 set as 100)
ITARDA INFORMATION no.131lSpeciafeatureAre elementary school students being made to wear their seatbelts properly?
~ Protecting elementary school student passengers in cars from accidents ~Fig. 3 shows that for both elementary school students and adults, the degree of decline in the number of fatalities
or serious injuries in “seatbelt non-use” cases per 100,000 population is smaller in “rear seats” than front
passenger seats, and the degree of decline is the smallest for elementary school students in “rear seats.”
As for reasons why the decline in the number of fatalities or serious injuries has been relatively slow in the case of“rear seats”, looking at the history of initiatives related to car safety measures such as the installment of SRS
airbags and reinforcement of car bodies, safety measures for the driver’s seat and front passenger seat appear tohave been carried out in advance of those for the “rear seats,” and this seems to have had an effect.
Among elementary school students, there appears to be a problem in which the decrease in the number offatalities or serious injuries in “seatbelt non-use” cases per 100,000 population has been slow in “rear seats.”■ Trend in number of fatalities or serious injuries in “seatbelt non-use” cases per 100,000

population among elementary school students

The analysis thus far has shown that “elementary school students account for a high percentage of seatbelt
non-use cases in rear seats,” and that “in the case of elementary school students, the decrease in the number offatalities or serious injuries in ‘seatbelt non-use’ cases per 100,000 population has been slow in ‘rear seats.’”
We will now take a look at the overall trend in the number of fatalities or serious injuries in “seatbelt non-use”
cases per 100,000 population, which also includes cases in which elementary school students are riding in thefront passenger seat. Fig. 4 shows this trend in and after 2001.

(Passengers in front and rear seats in medium and kei passenger cars only)120

The degree of decline for all “seatbelt
non-use” cases, including cases in whichelementary school students are riding in
the front passenger seat, is small!

100

Index

80

60

40

20

0
2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

n＝1,571

2005

2004

2003

2002

2001

6-12 years

20-64 years

n＝15,074

Fig. 4. Trend in number of fatalities or serious injuries in “seatbelt non-use cases”
per 100,000 population among elementary school students and adults(With number of fatalities or serious injuries per 100,000 population in 2001 set as 100)

Based on Fig. 4, it is apparent that the decrease in the overall number of fatalities or serious injuries in “seatbelt
non-use” cases per 100,000 population, which includes cases in which elementary school students are riding in
the front passenger seat, has been slow. This trend seems to be one reason why the decrease in the overall
number of fatalities or serious injuries among elementary school students, which is shown in Fig. 2, has been slow.
One should not get the mistaken impression that riding in a “rear seat” is the problem. The problem is that there
are many “seatbelt non-use” cases when the riding position is a rear seat. “Seatbelt non-use” cases are dangerous
situations that can lead to serious injuries. In order to decrease the number of fatalities or serious injuries,
thorough use of seatbelts must first of all be carried out.

ITARDA INFORMATION no.131

ITARDA INFORMATION no.131

Even in “seatbelt use” cases, effects of seatbelt use are sometimes

3 not being sufficiently obtained among elementary school students■ Trend in the number of fatalities or serious injuries in “seatbelt use” cases per 100,000

population among elementary school students

We will now perform an analysis regarding the number of fatalities or serious injuries in “seatbelt use” cases.
First, take a look at the trend in the number of fatalities or serious injuries in “seatbelt use” cases per 100,000
population among elementary school students. Fig. 5 shows this trend in and after 2001.
(Passengers in front and rear seats in medium and kei passenger cars only)

140

Among elementary school students,
the degree of decline is small evenin “seatbelt use” cases!

120
100

Index

80
60
40
20

6-12 years

20-64 years

n＝1,0010n＝22,049

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

Fig. 5. Trend in number of fatalities or serious injuries in “seatbelt use” cases
per 100,000 population among elementary school students and adults(With number of fatalities or serious injuries per 100,000 population in 2001 set as 100)

Based on Fig. 5, it is apparent that among elementary school students, “the decrease in the number of fatalities orserious injuries in ‘seatbelt use’ cases per 100,000 population has been slow.” As with the slow decrease
regarding “seatbelt non-use” cases, the slow decrease regarding “seatbelt use” cases seems to be a factor behind
why the overall decrease in the number of fatalities or serious injuries among elementary school students, which isshown in Fig. 2, has been slow.
Why has the decrease in the number of fatalities or serious injuries been slow even in “seatbelt use” cases?
■ Injured body part in “seatbelt use” cases
We would now like to take a look at the “injured body part” and analyze this as a factor related to why the decreasein the number of fatalities or serious injuries in “seatbelt use” cases per 100,000 population has been slow. Here,“injured body part” refers to the part of the body that sustained the principle damage leading to the fatality or
serious injury. Fig. 6 shows a comparison of the composition rates of injured body parts in fatalities or serious
injuries in “seatbelt use” and “seatbelt non-use” cases in 2001 through 2018.
Based on total number of fatalities or serious injuries in 2001 through 2018

100

Comprehensive/
other

80

Arm/leg

60
40
20
0

Chest/abdomen/
lower back3.1-times higher
25％
Elementary school
students (6-12 years) Adults (20-64 years)
n＝1,001

n＝22,049[Seatbelt use]

1.5- times higher

Neck
Head/face

38％
Elementary school
students (6-12 years)
n＝1,571

Adults (20-64 years)
n＝15,074[Seatbelt non-use]

Fig. 6. Composition rates of injured body parts in fatalities or serious injuries
ITARDA INFORMATION no.131lSpeciafeatureAre elementary school students being made to wear their seatbelts properly?
~ Protecting elementary school student passengers in cars from accidents ~Fig. 6 first of all shows that the rate for the injured body part “head/face” is higher for elementary school students
than for adults. It is generally said that in the case of children, there is a tendency for the upper body to tilt forward
at the time of an impact since the head is large relative to the size of the rest of the body and the center of gravity
is high 2). As a result, the “head/face” part comes in contact with the inside of the car cabin and sustains injuries
more frequently compared with adults.
Also, it is clear that when seatbelt is worn, the rate for the injured body part “head/face” is lower compared with“seatbelt non-use” cases (38% → 25%), and that seatbelt use has the effect of reducing the number of cases inwhich the “head/face” comes in contact with the car.
Meanwhile, the rate for the injured body part “head/face” was 1.5-times higher for elementary school students thanfor adults in “seatbelt non-use” cases and 3.1-times higher for elementary school students than for adults in“seatbelt use” cases.
■ Mechanisms of injury in “seatbelt use” cases based on injured body parts and injury-inflicting

car parts

In the case that elementary school students and adults are restrained to their seats in a similar manner in seatbelt
use cases, elementary school students, which have about half the body weight and height of adults, are thrownfrom car seats less frequently during accident impacts. It seems that the reason the rate for the injured body part“head/face” is higher among elementary school students in spite of this logic is that “elementary school students
might actually not be receiving the same restraining force from seatbelts as adults.”
We will consider this based on the injured body part and the part of the car that inflicted the injury (injury-inflicting
car part). Tables 2-1 and 2-2 show the composition rates (%) of the injured body part and injury-inflicting car part
combinations in fatalities or serious injuries in “seatbelt use” cases. The size of the dots on the table corresponds
to the size of the composition rate.

Table 2-1. Composition rates (%) of injured body parts and injury-inflicting car partsin fatalities or serious injuries in “seatbelt use” cases among elementary school students（n＝1,001）

Ejectedfrom carDashboard
Steering
Windshield
area
wheel

Door/
window

Pillar

Roof

Seat
（2）

Head/face（1）

6

Other parts Parts ofof carcar
interior
exterior,
etc.
9

Neck

11

Chest/abdomen/
lower back

11

11

10

10

Arm/leg

5

Other(Based on the total number of fatalities or serious injuries in 2001 through 2018.
When 0 when rounded down to nearest whole number: blank space; when 1 to below 5: ● only.)

Table 2-2. Composition rates (%) of injured body parts and injury-inflicting car partsin fatalities or serious injuries in “seatbelt use” cases among adults（n＝22,049）

Ejectedfrom carDashboard
Steering
Windshield
area
wheel

Door/
window

Pillar

Roof

Seat
（2）

Head/face

Other parts Parts ofof carcar
interior
exterior,
etc.

（1）

Neck
Chest/abdomen/
lower backArm/leg

19
5

14

15

5

9

Other
(Based on the total number of fatalities or serious injuries in 2001 through 2018.
When 0 when rounded down to nearest whole number: blank space; when 1 to below 5: ● only.)
ITARDA INFORMATION no.131

ITARDA INFORMATION no.131
By comparing Tables 2-1 and 2-2, the characteristics of (1) and (2) on the tables become apparent. Based on (1), it
is clear that the "head/face" part comes into contact with many car parts in the case of elementary school students
compared to adults. In other words, "there is a higher frequency of being thrown from the seat even in seatbelt
use" cases.
Looking at the injury-inflicting car parts “seat” and “other parts of car interior” in (2), more than 70% injuries arebeing inflicted by these parts. Seatbelts are also concerned with these injury-inflicting car parts. Since passengers
are restrained to their “seat” with a seatbelt, seatbelts have some effect on this car part. “Other parts of car
interior” consists of the injury-inflicting car parts such as console box, shift lever, and so on, and it also includes
seatbelts.
Under (2), the injured body parts for adults are mainly concentrated at the trunk of the body in the “neck” and“chest/abdomen/lower back” parts. This seems to be due to the fact that the seatbelt is restraining the passenger
in an effective manner, so many of the injuries that are sustained are from pressure from the seatbelt itself, andshaking and whiplashing of the body while it is restrained to the seat with the seatbelt.
Meanwhile, in the case of elementary school students, the injured body parts are mainly “head/face” and “arm/leg”
and relatively few injuries are sustained in “neck” and “chest/abdomen/lower back.” In other words, unlike adults,
many injuries are sustained at parts of the body that are slightly away from the trunk, and thus it seems that“relatively few injuries are sustained from the seatbelt itself and restraining of the body to the seat with theseatbelt.” Thus, as suspected, there seems be a “possibility that seatbelts are not restraining as effectively as they
are with adults.”
Therefore, it appears that the decrease in the number of fatalities or serious injuries in “seatbelt use” cases has
been slow because the effects of seatbelt use are not sufficient.
Why has it not been possible to obtain a sufficient level of effects from seatbelt use?

Why effects of seatbelt use are not being sufficiently
4 obtained among elementary school students
It is generally said that seatbelts are effective when the passenger’s height is 140 cm or above, and thus seatbelts
sometimes do not fit the passenger’s body frame until the passenger is around 10 years old. There are survey
results showing that child passengers wear seatbelts in a variety of ways when riding in cars3)-4). As shown in Table
3, these include wearing the seatbelt at a shifted angle or with poor body posture (sprawling, etc.) due to feelingthat the correct position is uncomfortable, and having the shoulder belt become misaligned due to steering
maneuvers of the driver for avoiding obstacles and so on. It seems that when accidents occur while seatbelts arebeing worn in such ways, there are many cases in which injuries are sustained because effects from seatbelt use
are not obtained.

Table 3. Examples of ways shoulder belts are worn by child passengers(Information on lap belt omitted from figure.)
Shoulderbelt

Worn correctly

Worn at shifted angle

Worn with poor
body posture

Misalignment of childʼsshoulder belt resulting fromsteering maneuver of driver

In order for the effects of seatbelt use to be obtained, the following is required. “The seatbelt must be worn
properly while maintaining the correct body posture based on eliminating discomfort related to the seatbelt. This isachieved by adjusting the height of the shoulder belt and height of the seat (in the case of a front passenger seat),or using a child safety seat for school-age children (which is sometimes referred to as a “booster seat”), whichmarket analysis of accidents in the United States has shown to be effective for reducing the risk of serious
injuries5)-6), etc.”
ITARDA INFORMATION no.131

参考文献
1) 総務省統計局
人口推計の結果の概要(2001-2018) https://www.stat.go.jp/data/jinsui/2.html
2）国民生活センター 小児の頭部外傷の実態とその予防(1997)
3）Jakobsson.L, et al Older children s sitting posture when riding in the rear seat IRCOBI Conf., (2011)4) Jakobsson.L, et al Rear seat safety for children aged4-12: Identifying the real-world needs towards
development of countermeasures 25th Int. ESV Conf., (2017)5）Arbogast.K, et al Belt-positioning booster seats : an update assessment. Pediatrics (2009)
6) Anderson.DM, et al Booster seat eﬀectiveness among older children: Evidence from Washington state
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ITARDA INFORMATION no.131

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No.131

公益財団法人 交通事故総合分析センター
令和元年8月 〒101 0064 東 京 都 千 代 田 区 神 田 猿 楽 町 ２ ７ ８(Masanori Taniguchi)

ITARDA INFORMATIONIn this special feature, since most fatality or serious injury accidents among 6 to 12-year-old children
involve elementary school students, we referred to these as “fatality or serious injury accidents
among elementary school students,” and we analyzed these from the perspectives of “seatbelt
non-use” and “seatbelt use” cases.
For elementary school students,● While the rate of seatbelt non-use cases in rear seats is about the same as that for adults,
because it is more common for elementary school students to ride in rear seats, elementary
school students account for a higher “rate of seatbelt non-use cases in rear seats” than adults.
Due to this and the fact that the decrease in the number of fatalities or serious injuries per
100,000 population when the riding position is “rear seat” has been slow, the overall decrease in
the number of fatalities or serious injuries in “seatbelt non-use” cases per 100,000 population has
been slow.
● The overall decrease in the number of fatalities or serious injuries per 100,000 population has
been slow in “seatbelt use” cases as well. This is because during impacts in accidents, the effects
of seatbelt use are not being sufficiently obtained as the result of improper use of seatbelts orbody posture.
As a result of the above:● Since the decrease in the number of fatalities or serious injuries per 100,000 population has beenslow in both “seatbelt non-use” and “seatbelt use” cases, the overall decrease in the number offatalities or serious injuries per 100,000 population has been slow.
When elementary school students are riding together, they should be made to ride in a rear seat asmuch as possible, and always be made to wear a seatbelt. Please make sure that they are sitting
squarely in their seat and are able to sit comfortably when riding in the car, and also please check tomake sure that the lap belt is near the pelvis. If the seatbelt position does not fit the child, please
make adjustments by using a child safety seat for school-age children, etc.
There is a need for guardians to be more thorough about carrying out the above in order to protect
elementary school students from being harmed in accidents.

交通事故分析レポート

5 Conclusion