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.111lSpeciafeatureReducing the number of
injured people while driving

Index
1.6
1.4

Injuries

1.2
1
0.8
0.6
0.4

Decline rate is lessthan that of fatalities

0.89
Fatalities
0.40

Always wear
seatbelts to
reduce thedamage level of
injuries!!

0.2
01993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013

Fig.1 Trend in numbers of fatalities and injuries
in traffic accidents (Index for 1993 data taken as 1)

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2 Characteristics of injury accidents ・
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3 Case examples of accidents・
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4 Conclusion ・
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・P9

l
SpeciafeatureReducing the number of injured people while driving

1 Introduction●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●■Trend in number of injured people in accidents
Fig.1 shows that the decline rate of the number of injured people (=serious injuries + slight injuries;
hereafter “injuries”) is less as compared to that of fatalities. The trend shows that the injuries are almost
constant at approx. 1.2 times the number of accident occurrences. But when the rates of fatalities andinjuries are compared, whereas fatalities are declining over the years, injuries continue to increase. It canbe inferred that advancements in car technologies and medical services have managed to reduce thedamage in accidents from fatalities to serious or slight injuries (Table 1).
Table 1 Trend in accidents and injuries
Injuries

With respect to fatalities + injuries

Accidents(cases)Fatalities(people)Injuries(people)Accidents

1993

724,678

10,945

878,633

1.21

1.2

98.8

1994

729,461

10,653881,723

1.21

1.2

98.8

1995

761,794

10,684

922,677

1.21

1.1

98.9

1996

771,085

9,943

942,204

1.22

1.0

99.0

1997

780,401

9,642

958,925

1.23

1.0

99.0

1998

803,8829,214

990,676

1.23

0.9

99.1

1999

850,371

9,012

1,050,399

1.24

0.9

99.1

2000

931,950

9,073

1,155,707

1.24

0.8

99.2

2001

947,2538,757

1,181,039

1.25

0.7

99.3

2002

936,950

8,396

1,168,029

1.25

2003

948,281

7,768

1,181,681

1.25

2004

952,709

7,425

1,183,616

1.24

2005

934,339

6,927

1,157,115

1.24

2006

887,257

6,403

1,098,566

1.24

2007

832,691

5,782

1,034,653

1.24

2008

766,382

5,197

945,703

1.23

2009

737,628

4,968

911,215

1.24

2010

725,903

4,922

896,2942011

692,056

4,663

2012

665,1382013

629,021(people/case)

Rate of fatalities (%)

0.7
0.6

99.3
99.3
99.4

0.6

99.4

0.6

99.4

0.6

99.4

0.5

99.5

0.5

99.5

1.23

0.5

99.5

854,610

1.23

0.5

99.5

4,411

825,396

1.24

0.5

99.5

4,373

781,494

1.24

0.6

99.4

Increase

DeclineConstant at 1.2 times

0.7≈

Rate of injuries (%)■Rate of injuries and fatalities by type of accidents
Table 2 shows the rate and number of injuries and fatalities in total casualties for the year 2013 by typeof accidents. The rate of injuries in vehicle to vehicle accidents is overwhelmingly high. As such, when
we analyzed by type of accidents the numbers of injuries and fatalities in vehicle to vehicle accidents
involving drivers as primary and secondary parties, as seen in Fig.2, “head-on/rear-end/angle collisions”
accounted for 70% of both the injured and dead.
Table 2 Rate and number of injuries andfatalities by type of accident (2013)
Vehicle tovehicleInjuries

Fatalities

Vehicle topedestrianHead-on collision

Injuries

72

Rear-end collision

Angle collision

SinglevehicleRate(%)

88.9

7.8

3.3

No. of people

694,923

60,737

25,834Rate(%)

40.3

34.3

25.4

No. of people

1,762

1,502

1,109

Others70

Fatalities
0％

Head-oncollision

Rear-end
collision

20％

Angle collision

40％

60％

Others80％

100％

Fig. 2 Rate of injuries and fatalities of primary andsecondary party drivers in vehicle to vehicle
accidents by type of accident (2013)

In this issue, we therefore intend to isolate the factors that influence injury accidents involving primaryand secondary party drivers and suggest ways to reduce the number of people injured.
<Except for Tables 6 and 8, the following data is based on the Road Traffic Accident Statistics from 2009
to 2013>
2 ITARDA INFORMATION no.111

ITARDA INFORMATION no.111

2 Characteristics of injury accidents●●●●●●●●●●●●●●●●●●●●●●●■Injuries are more when colliding part is “front” and “rear-end”
We analyzed the colliding part and degree of injury to human body in head-on, rear-end and angle collisionsof four-wheeled vehicles (excluding other type of motor vehicles) involved as primary and secondary parties
in injury accidents (Table 3). In the case of primary parties, the rate is highest when the colliding part is frontof the vehicle, while it is the rear for secondary parties. Whereas the rate of head-on collisions for secondary
parties is less than the rear-end collisions, the number of injuries is more for head-on collision in secondary
parties than that of primary parties. Therefore our subsequent focus shall be on the data of rear-end collisionin secondary parties and the head-on collision in primary/secondary parties. For reference, the number offatalities for both primary and secondary parties was high for head-on collisions.
Frontleft

Table 3 Colliding part of the vehicle and degree of injury to human body

Front

Frontright

Rear

Rearright

Colliding part of the vehicle

SecondaryPrimary
Secondary

Fatality
PrimaryRate(%)

Front

FrontrightSideright

Rearright

Rear

10.7

8.1

6.7

3.9

56.9

3.2

5.3

5.1

92,15853,355776,541

44,33372,38870,298

No. of people 146,164 110,088

Rear-left Side-left Front-leftRate(%)

42.0

16.8

7.9

1.9

2.1

2.1

10.1

17.0

No. of people

64,21625,70912,131

2,964

3,150

3,184

15,43925,934Rate(%)

37.3

21.9

10.2

3.3

11.9

1.3

7.4

6.7

No. of people

201

118

55

18

64

7

40

36

Rate(%)

59.8

16.2

7.4

0.4

0.8

0.3

6.3

8.8

No. of people

2,425

657

298

17

31

14

254

358

Side-left

Injury(serious +slight)Party

Side-right

Degree of injury
to human body

n=1,365,325
n=152,727
n=539

Rearleft

n=4,054■What was the speed just before the collision?
It is hard to estimate the speed of the vehicles before collision, so that as a measure of speed duringcollisions that led to injuries, Quasi-ΔV*1 values (Since the Danger Perception Speed (hereafter “DPS”) of
the driver based on the estimated variance in vehicle speed before and after collision (hereafter “collision
speed”) and the complete vehicle curb mass is used for calculation purposes, there may be chances that
it is lower than the speed before collision due to deceleration etc.), is used for the analysis.
Fig.3 shows the rise in the rate of injuries in the head-on and rear-end collisions of secondary parties andthe head-on collisions of primary parties. Rear-end collisions of secondary parties accounted for maximum
injuries at 87% when the collision speed was 20km/h or less. Speaking in extreme, if rear-end collisions ofsecondary parties at a collision speed of 20km/h or less can be eliminated, as much reduction in injuries
could be achieved. Similarly, the rate of injuries stands at 89.2% for head-on collisions at 70km/h or less inprimary parties and at 88.7% for head-on collisions at 50km/h or less in secondary parties.
％
100

Cumulative rateof injuries

Secondary
party:
rear-end

Secondary

87.0 party: head-on

80

88.7

89.2

Primary
party:
head-on

60
40
20
0

Colliding partPrimary party: head-on
Secondary party: head-on

Secondary party: rear-end

About 90% of the injuries←

Quasi-ΔV～10km/h～20km/h～30km/h～40km/h～50km/h～60km/h～70km/h～80km/h～90km/h～100km/h

over
100km/h

1.1

8.2

22.2

45.7

67.0

80.9

89.2

94.1

97.2

98.8

100.0

7.9

26.2

48.9

72.9

88.7

95.9

98.7

99.6

99.8

99.9

100.0

56.2

87.0

97.5

99.4

99.9

100.0

100.0

100.0

100.0

100.0

100.0

Fig. 3 Cumulative rate of injuries by colliding part of vehicle and Quasi-ΔV (collision speed)

Unit: %ITARDA INFORMATION no.111 3

lSpeciafeatureReducing the number of injured people while driving※1 Quasi-ΔV refers to the estimated variance in vehicle speed before and after collisionand is calculated based on danger perception speed of the colliding vehicle and complete
vehicle curb mass of the vehicle. Here it is shown as “collision speed.”

V1

For reference: Consider that your vehicle (1) and otherparty’s vehicle (2) collide, then the estimated equation for“Collision speed” (Quasi-ΔV) of your vehicle during head-on
collision is as follows:
ΔＶ1=M2／（M1+M2）×（V1+V2）
where
M = complete vehicle curb mass,V = danger perception speed

V2

Supposing M1 is 1000kg and M2 is 1500kg
while the danger perception speed for both
vehicles is 50 km/h, thenΔV1 = 60 km/h.

■70% of the injuries can be reduced if danger is evaded at a DPS of 40km/h or less
Further, we analyzed the correlation between DPS and collision speed (Quasi-ΔV). In the case of rearend collision of secondary parties, there may be situations when the driver cannot do anything even if he/she perceives danger; therefore we considered the DPS of primary parties. Also, for head-on collisions,the result for primary and secondary drivers is totaled and the DPS of “vehicle drivers” is considered.
The blue-shaded cells in Tables 4 and 5 show the presumed number of people who escaped with noinjuries when the “primary party drivers” or the “vehicle drivers” explained above perceived danger
and applied brake at a DPS of 40km/h or less. In the real world, accidents may not always be avoided
completely even if the speed is low. However, as evident from Tables 4 and 5, 86.5% injuries from rearend collisions of secondary parties and 67.7% injuries from head-on collisions of vehicles have beensaved respectively when the DPS is less.
Table 4 Correlation between DPS and Collision speed of the injured in “rear-end collisions of secondary
parties”
Collision speed of secondary party (Quasi-ΔV)〜10km/h 〜20km/h 〜30km/h 〜40km/h 〜50km/h 〜60km/h 〜70km/h 〜80km/h 〜90km/h 〜100km/h

over
100km/h

DPS of primary party driver

Stopping 〜10km/h

228,819

0

0

0

0

0

0

0

0

0

〜20km/h124,696

9,615

0

0

0

0

0

0

0

0

0

〜30km/h26,32888,553

2,373

0

0

0

0

0

0

0

0

〜40km/h

8,157

91,59927,227

1,682

0

0

0

0

0

0

0

〜50km/h

3,938

21,07933,380

5,741

1,040

0

0

0

0

0

0

〜60km/h

1,795

3,703

9,029

4,349

173

341

0

0

0

0

0

〜70km/h

549

813

942

1,008

353

287

46

0

0

0

0

〜80km/h

393

593

381

472

245

112

90

3

0

0

0

〜90km/h

317

410

151

86

83

32

13

17

1

0

0

〜100km/h

315

482

121

44

57

40

9

7

5

0

0

over 100km/h

108

223

103

19

11

5

6

2

0

1

0

1
Unit: People

Rate of blue-shaded cells in total=86.5%

Table 5 Correlation between DPS and Collision speed of the injured in “head-on collisions of vehicles”
Collision speed of vehicle (Quasi-ΔV)〜10km/h 〜20km/h 〜30km/h 〜40km/h 〜50km/h 〜60km/h 〜70km/h 〜80km/h 〜90km/h 〜100km/h
Stopping 〜10km/h

over
100km/h

DPS of vehicle driver

823

1,269

451

86

16

5

1

1

0

0

0

〜20km/h

77

583

471

172

28

7

3

1

0

0

0

〜30km/h

47

370

1,240

723

188

41

7

1

0

1

0

〜40km/h

60

259

1,022

2,064

1,124

387

140

34

8

1

0

〜50km/h

51

154

306

885

1,309

717

304

169

93

22

3

〜60km/h

28

55

76

173

234

285

190

78

49

36

34

〜70km/h

3

9

10

18

42

53

38

21

9

9

9

〜80km/h

0

1

3

5

9

13

20

7

4

7

6

〜90km/h

1

1

1

1

2

5

1

4

2

0

4

〜100km/h

0

2

0

2

4

0

3

3

1

2

0

over 100km/h

0

0

0

0

0

0

0

0

0

0

0
Unit: People

Rate of blue-shaded cells in total=67.7%

4 ITARDA INFORMATION no.111

ITARDA INFORMATION no.111■ Correlation between the speed and distance to avoid collision (Rear-end collision withstopped vehicle)
Sparing the details, 88.7% of the rear-end collision type of accidents happened with stopped vehicles.
Calculations based on Table 3 indicates that 51.4% of the injured resulted from rear-end and 13.9% fromhead-on collisions. Consequently, we analyzed the time good enough for noticing a vehicle stopped in
front to avoid collision with it.
Upper section of Table 6 shows the correlation between the driving speed and stopping distance ofvehicles and the time taken to stop the vehicle by the sliding friction coefficient (hereafter “SFC”) of roadsurface. The lower section shows the driving distance for each of the speeds in 3 seconds (=1 sec ofidle running time + 2 sec, an estimate of safe inter-vehicle distance recommended by the Metropolitan
Police Department etc.1) 2)). Accordingly, if a stopped vehicle is noticed 3 seconds earlier, collision can be
avoided even at a speed of 20km/h or less when the vehicle is running on a frozen road with a SFC of 0.15;
however, collisions can be avoided only upto paved road (wet) with a SFC of 0.4 and upto to a speed of
50km/h. Nevertheless, the required distance varies with the speed of other vehicle, road surface and tireconditions, among other factors. Therefore in order to avoid accidents, it is necessary to pay attention
forward and to drive at a speed where one can quickly notice the other vehicle and stop.
Table 6 Speed, stopping distance and stopping time of vehicles by sliding friction coefficient of roadsurface1)2) (at idle running time of 1 sec)
SFC of road surface

0.7 Paved (dry)
0.4 Paved (wet)0.3 Snow-covered
0.15 Frozen(

Speed km/h

10

20

30

40

50

60

70

80

90

100

Stopping distance (m)

3.3

7.8

13.4

20.1

28.0

36.9

47.0

58.2

70.6

84.0

Stopping time (sec)

1.4

1.8

2.2

2.6

3.0

3.4

3.8

4.2

4.6

5.0

Stopping distance (m)

3.8

9.5

17.2

26.9

38.5

52.1

67.7

85.2

104.7

126.2

Stopping time (sec)

1.7

2.4

3.1

3.8

4.5

5.3

6.0

6.7

7.4

8.1

Stopping distance (m)

4.1

10.8

20.1

32.1

46.7

63.9

83.7

106.2

131.3

159.0

Stopping time (sec)

1.9

2.9

3.8

4.8

5.7

6.7

7.6

8.6

9.5

10.4

Stopping distance (m)

5.4

16.1

32.0

53.1

79.5

111.2

148.0

190.2

237.6

290.2

Stopping time (sec)

2.9

4.8

6.7

8.6

10.4

12.3

14.2

16.1

18.0

19.9

Combinations where the vehicle can be stopped within the stopping distance of 3 seconds)
Stopping distancein 3sec (m)

8.3

16.7

25.0

33.3

41.7

50.0

58.3

66.7

75.0

83.3

The above values for sliding friction coefficient of road surface are referred from the following materials 1) and 2).
Stopping distance/stopping time is calculated from the equation, mα＝-μmg; where m= vehicle mass (kg), α= deceleration (m/s 2), μ=sliding friction
coefficient of road surface and g= acceleration due to gravity (m/s2).
1) Public Works Research Center (general incorporated foundation), Technical Research Center, Road Research Department: Sliding Friction of Road
Surfaces, Criteria for Road Surface Management and Sliding Accidents; Civil Engineering Journal 52-5 (2010), Table 2.3)
2) Shinnippon-Hoki Publishing Co., Ltd. – Table of braking time and braking distance for dry/wet asphalt roads4), Handbook on compensation for damages
in traffic accidents.

350

m

350
300

250

250

200

200

150

150

100

100

50

50

0

0

10

0

25

Sec

0.15 Frozen road20
0.3 Snow-covered road15
0.4 Paved road
10 (wet)5 (dry)0.7 Paved road200

30 1040 2050 3060 4070 5080 6090 7010080
Speed
Speed
km/h

90

Fig. 4 Vehicle speed and stopping distanceby SFC of road surface

0
100 0
km/h

25

Stopping time (sec)

Stopping distance (m)

300

m

10

Sec
0.15 Frozen road20

0.3 Snow-covered road

15
10

0.4 Paved road (wet)5

0.7 Paved road (dry)020
030 10 40 20 50 30 60 40 70 50 80 60 90 70 10080
Speed
Speed
km/h

90

100
km/h

Fig. 5 Vehicle speed and stopping timeby SFC of road surface

ITARDA INFORMATION no.111 5lSpeciafeatureReducing the number of injured people while driving■ Always wear seatbelt to reduce the level of injuries due to collisions
Table 7 shows the number of injured people for the top three body parts mainly injured (neck, chest, andwaist) by the state of main injuries. Apparently, ① neck sprain tops the list, followed by ② ③ (refer ④)
for “scratch, abrasion or bruise” in neck, chest and waist, in that order. The chest and waist injuries were
sustained due to restraining by seat belts, while the neck injuries due to whiplash in the absence of a
restraining object or the rubbing of the seatbelts. Sparing the details, when the seatbelt is not fastened,
injuries like scratch, abrasion or bruise on the head in the cases of head-on collisions of primary parties
and the rear-end collisions of secondary parties, and injuries like leg fracture in the case of head-on
collisions of primary parties are more in number. This is indicative of the fact that on collision, not fastening
the seatbelts would have resulted in significant movement of passengers, leading to injuries due to impact
with vehicle parts. It is mandatory to fasten the seatbelt when occupying a vehicle. It plays an importantrole in reducing the injury level in accidents.
Table 7 Number of injured people by body parts mainly injured and state of main injuries
Body
parts
mainlyinjuredState ofmain injury＊1

Secondary party:
Rear-end collision

Scission
Fracture
Rupture of
Neckinternal organs
SprainDislocation
Scratch,abrasion or bruise
Scission
Fracture
Rupture of

Chest

abrasion or bruise＊1：Excludes drowning, death fromsuﬀocation/drowning etc.

0
156

0
198

0
415

13

5

0

525,450692①

72,166104①

18,92154②

171,549②

28,508②

8,778internal organs
SprainDislocation
Scratch,internal organs
SprainDislocation
Scratch,Primary party:
Head-on collision

①

1
443

8
3,059

5
4,274

1

8

36

851
20

344
13

172
15

2,540

abrasion or bruise
Scission
Fracture
Rupture of
Waist

Secondary party:
Head-on collision

③

9,639

③

①②
③

③④

7,440

0
116

0
252

0
847

1

2

4

④

15,391
36

2,781
21

619
14

③

15,929

3,759

1,182

Unit: People

Unit: People

Unit: People■ Whiplash Injury Lessening seats are effective in reducing neck injuries

Seatbelts play a vital role in suppressing injuries in accidents; nevertheless, many people sustain
injuries in the neck region as the head movement is not restrained by any object. Whereas the legal
requirements of neck injury standards are met with, new vehicles sold in recent times equipped with
Whiplash Injury Lessening (WIL) seats are becoming increasingly popular. These seats have modified
structures and have mechanisms to reduce neck injuries in collisions, such as the head restraint lunges
forward in case of an accident.
Table 8 shows the rate of neck injuries with or without the WIL seats installed in vehicles, indicating lower
rate of injuries if installed. WIL seats were installed in 56.3% 5) of the passenger cars manufactured in2012 and the percentage of vehicles equipped with WIL seats is expected to increase in future.

6 ITARDA INFORMATION no.111

ITARDA INFORMATION no.111

Table 8 Rate of injuries in collision accidents by presence/absence of WIL seats(Cumulative total of 8 Japanese car manufacturers from 2008-2012)
WIL seats

Level of injury

Body part mainly injured

Rate against total injuries※ (%)

Present

Serious/slight injury

AbsentNo injury
Serious/slight injury

Neck
Other parts
Other parts
Neck
Other parts
Other parts

21.7
1.8
22.9
24.7
2.4
26.4

No injury※Total injuries, n=534,736

3 Case examples of accidents●●●●●●●●●●●●●●●●●●●●●●●●●●●●

The case examples in this section indicate the significance of “danger prediction,” “seatbelt” and“deceleration till accidents occur”, so utilize these learnings in your routine driving.
・ Case example 1) Victim of rear-end collision, anticipated and prepared himself for the collision, so
escaped with slight injuries.
・ Case example 2) Perpetrator in rear-end collision, had not fastened the seatbelt and died in theaccident.
・ Case example 3) Head-on collision. Both parties decelerated, so the level of injury was slight.
Case example 1)
This rear-end collision with a parking vehicle occurred on a 4-lane, two-way traffic straight road withunobstructed view. Mr. A, in his late twenties driving a commercial vehicle stopped in lane-1 of anintersection with traffic signal. Although Mr.A had noticed a stopped vehicle 100m ahead of him, as soon
as the signal turned green, he speeded up in an effort to move to lane-2 by overtaking the vehicle parallel
to him. He was so engrossed in this action that he was too late in noticing that he had approached too
close to Mr.B and collided with the stopped vehicle at a speed of 80km/h, unable to apply a brake.
On the other hand, Mr.B, in his late fifties driving a passenger car had stopped his vehicle in lane-1 ashe had felt sick while driving, and was about to get down of his car. At that moment he took notice of the
speeding vehicle of Mr.A in his rear-view mirror and in a fluster closed the car door and held tightly on to
the steering wheel and planted his feet firmly in preparing himself for the collision. In this collision, therear side of Mr. B’s car was badly damaged; however he escaped with a slight injury of cervical sprain.
Despite not been able to fasten his seatbelt, the reason for Mr.B sustaining only a sprain in the neck is
because he had “prepared himself for the collision by holding firm” to restrain his body movement when
he gathered that the collision was inevitable.” Therefore, when stopping your vehicle at a place where
there is a possibility of collision, it is important to heed more attention to traffic in the rear than when one
is driving, so as to prepare oneself in case a collision occurs.

(Case example 1: Diagram of accident site)
Type of accident: Rear-end collision between two
four-wheeled vehicles
Mr. A: In his late twenties, driving a commercial vehicle,
slight injury (abdominal contusion), medium
damage to front side of his vehicle.
Mr. B: In his late ﬁfties, driving a passenger car, slight injury(cervical sprain), serious damage to rear side of his
car.

(Case example 2: Diagram of accident site)
Type of accident: Rear-end collision between two

Passenger car

A Commercial vehicle

Passenger car

Large commercial
vehicleITARDA
INFORMATION no.111 7BlSpeciafeatureReducing the number of injured people while driving

Case example 2)This rear-end collision accident occurred in a signal-waiting traffic congestion on a straight road withunobstructed view. Ms. A, in her early fifties driving a passenger car who was the perpetrator in this
accident
died inthis accident
and oninvestigation it was found that her car collided at a speed of(Case example
1: Diagramof accident
site)
40km/h onto a large commercial vehicle driven by Mr.B (in his early thirties) stopped at the tail-end ofType of accident: Rear-end collision between two
the congestion. Medium damage was caused to Ms. A’s car, but deformation in the car interior was
four-wheeled vehicles
negligible.
As Ms. A had sustained lacerated wound on her head when she was thrown over on to the
Mr. A: In his late twenties, driving a commercial vehicle,
front windscreenof her car, it was assumed that she had
not fastened
Passenger
car the seatbelt and the bruise in her
slight injury (abdominal contusion), medium
Commercial vehicle
abdominal
region was caused by the deployed airbag after she was thrown forwardfrom her seat.
damage to front side of his vehicle.
The
death
of
Ms.A
could
have
been
avoidedhadshefastenedtheseatbelt
as
this
would
have prevented
Mr. B: In his late ﬁfties, driving a passenger car, slight injury
her body
frombeing
thrownover
andallowedthenormaldeploymentoftheairbagandserve
its purpose(cervical sprain), serious damage to rear side of hisof impact
absorption.
Therefore
itisadvisable
toalwaysfastentheseatbeltfortheairbagas well tocar.
function properly.

B(Case example 2: Diagram of accident site)
Type of accident: Rear-end collision between two
four-wheeled vehicles(Case
1:ﬁfties,
Diagramof accident
site)
Ms.
A: example
In her early
drivinga passenger
car, died(abdominal
bruise),mediumdamagetofront side ofType of accident: Rear-end collision between two
her vehicle.four-wheeled vehicles
Mr. A:
B: In
In hishis late
earlytwenties,
thirties, driving
commercial
Mr.
drivingaalargecommercial
vehicle,vehicle,no injury,
rear sideof his vehicle
was slightly
slightinjury(abdominal
contusion),
mediumdamaged.
damageto front side of his vehicle.

Passenger car

Large commercial vehicle

A

B

Passenger car

B

Mr. B: In his late ﬁfties, driving a passenger car, slight injury(cervical sprain), serious damage to rear side of hiscar.

A

A Commercial vehicle

Case example 3)Thishead-onoccurredon site)a 7m wide curved road without a median line. Ms. A in her late(Case
examplecollision
3: Diagramof accident
fiftiesa 2:
passenger
at a speed(Casedriving
exampleDiagram ofcar
accidentsite) of 40km/h, was returning on this road with obstructed view
Type of accident: Head-on collision between two
after
dropping her family
memberat the hospital. SoPassenger
preoccupied
with thevehicle
thoughts of her
car wasLargeshecommercial
Type of accident: Rear-end
collision
between two
four-wheeledvehicleshospitalized father
that
shedrifted
to
the
right
side
of
the
road
and
realized
it
late.
When
she noticed a
Ms. A: In her late four-wheeledﬁfties, driving vehicles
a passenger car, slight
Passengercarvehicleapproachingfromthe aopposite
side,diedshe applied the brake.
Ms. A: In
her earlyﬁfties,driving
passenger
injury(bruisedchest),
mediumdamagecar,
toMs.B, in(abdominal
her late twenties
drivingapassenger
car approached the curve at a speed of 40km/h on the way
front side ofbruise),
her car medium damage to front side ofback from
work.
As
Ms.B
was
aware
that
the
road
had obstructed view, she kept her
vehicle toPassenger
carthe left sidevehicle.
Ms. B: her
In herlate twenties, driving a passenger car,
ofMr.
the
road.
When
she
saw
the
vehicleofMs.A
approaching
towards
herdeviatingfromtheopposite
lane,
B: In
his early
drivinglarge commercial
slightinjurythirties,(bruisedchest),a medium
damageshe steeredherto the left
and applied brake; but could not avoid it and resulted in a head-on collision.
vehicle,nocar
injury,to front sideof herrear
car side of his vehicle was slightly
This collision
could
have
been
avoided if Ms.A had paid attention forward. Although medium damage wasdamaged.
caused to both the vehicles on the front sides, both Ms. A and Ms.B decelerated their cars on perceiving
the danger. Applying brake alleviated the impact speed and allowed them to escape with only bruised
chests.

AB B

A(Case example 3: Diagram of accident site)
Type of accident: Head-on collision between two
four-wheeled vehicles
Ms. A: In her late ﬁfties, driving a passenger car, slight
injury (bruised chest), medium damage tofront side of her car
Ms. B: In her late twenties, driving a passenger car,slight injury (bruised chest), medium damage
to front side of her car

Passenger car

B
A Passenger car

6.7m
8 ITARDA INFORMATION no.111

■ Analysis result of injury accidents of primary and secondary parties while driving(1) The number of injured people is more for rear-end collisions of secondary parties,
followed by head-on collisions, whereas it is more for head-on collisions of primaryparties. However, head-on collisions of secondary parties resulted in more number of
injured people as compared to that of primary parties. Therefore, reduction in head-on
and rear-end collisions could help reduce the number of injured people.
(2) The following accidents account for about 90% of the injured for the corresponding
collision speeds (=Quasi ΔV)
・ Rear-end collisions of secondary parties at 20km/h or less・ Head-on collisions of primary parties at 70km/h or less・ Head-on collisions of secondary parties at 50km/h or less.
(3) A correlation has been found between the number of injured people and the Danger
Perception Speed (DPS) and collision speed.
(An estimate suggests that 86.5% injuries in rear-end collisions of secondary parties and67.7% injuries in head-on collisions of vehicles can be reduced if collisions within the
DPS range of 40km/h are prevented.)(4) Injuries are more in the neck, chest and waist regions. (Injuries are of serious naturewhen seatbelt is not fastened.)

References
1) Metropolitan Police Department homepage: Traffic safety/Notice to expressway users/Ways for avoiding collision accidents
http://www.keishicho.metro.tokyo.jp/kotu/kousoku/osirase1.htm
2) Saitama Prefectural Police homepage: Recommended inter-vehicle distance of 2sec or more
http://www.police.pref.saitama.lg.jp/f0010/kotsu/0102undou.html
3) Public Works Research Center (general incorporated foundation) - Technical Research Center, Road Research Department: Sliding
Friction of Road Surfaces, Criteria for Road Surface Management and Sliding Accidents; Civil Engineering Journal 52-5 (2010), Table 2.
compensation for damages in traffic accidents.
5) Japan Automobile Manufacturers Association, Inc. – Status of Installation of Safety Devices in Passenger Cars (2012).
http://www.jama.or.jp/safe/wrestle/wrestle_t1.html

公益財団法人 交通事故総合分析センター●ウェブサイト http://www.itarda.or.jp/●E メール koho@itarda.or.jp

イタルダインフォメーションに関するお問い合せ先 渉外事業課 TEL 03-5577-3973 FAX 03-5577-3980

本部〒101-0064 東京都千代田区猿楽町2-7-8 住友水道橋ビル8階
TEL 03-5577-3977(代表) FAX 03-5577-3980

つくば 交通事故調査事務所

ITARDA INFORMATION no.111 9275

住 友 水 道 橋 ビル８ 階

4) Shinnippon-Hoki Publishing Co., Ltd. – Table of braking time and braking distance for dry/wet asphalt roads, Handbook on

No.111

公益財団法人 交通事故総合分析センター〒101 0064 東 京 都 千 代 田 区 猿 楽 町 ２ ７ ８■ Precautions for reducing the number of injured people(1) The foremost thing is not to cause accidents. Therefore, it is important to maintainsufficient inter-vehicle distance and pay attention forward while driving. This will preparein perceiving any danger soon enough and applying brake to decelerate and in avoiding
the collision. Always fasten your seatbelt.
(2) Make efforts not to aggravate the level of damage in case of collisions.
・ About 90% of the rear-end collisions are caused at a low collision speed level of 20km/h or
less. Be careful about vehicles in the rear and if collisions are inevitable, brace yourself
by holding tightly onto the steering wheel and get a firm footing so as to reduce yourbody movement to as little as possible. It may be possible to reduce neck injury by
restricting the neck movement. When fellow passengers are present, shout and letthem also know about the danger and prepare themselves for the collisions.
・ In case of head-on collisions, the number of injured people is 34% more for DPS of
50km/h as compared to that of 40km/h. So dedicate yourself to driving at a lower
speed.
Masumi Nakano

ITARDA INFORMATION●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

交通事故分析レポート

4 Conclusion