Moreover, angle collision accidents at non-signalized intersections involving elderly drivers have thefollowing characteristics.
■ As people grow older, the percentage of accidents caused by a “failure to temporarily stop”
increases.
■ As people grow older, the percentage of accidents “when starting up” increases.
■ The following characteristics depend on the size of the intersection.
(1) At non-signalized intersections with two community roads, the percentage of accidents caused
by impaired visibility decreases.
(2) At non-signalized intersections with community road - highway, the percentage of accidents
with vehicles traveling rapidly increases.
(3) At non-signalized intersections with highway - communit y road, the percentage ofvehicle-vehicle accidents increases.
(4) At non-signalized intersections with two highways, the percentage of accidents with vehicles
traveling from the right-hand side increases.
In addition, it is believed that driving while taking heed of the following points is an effective way of
preventing angle collision accidents at non-signalized intersections.

■Especially for intersections with two narrow roads:
・ Even if an intersection has good visibility and an open field of view, drivers must not forget to check to
confirm that it is safe when passing through. They must pass through intersections with poor visibility
due to road-side structures, trees and shrubs, and other such obstacles by using curved traffic mirrors
etc., and be extra careful.
■Especially for intersections where drivers merge from a narrow road onto a broad road:・ Even when it appears that other vehicles are far away, they could potentially be traveling at a higher
speed than the driver imagines. When there is another vehicle present, drivers must wait for them to go
by before passing through the intersection.
■Especially for intersections with narrow roads when drivers are traveling on a broad road:・ Just because an intersection intersects with a narrow road, does not necessarily mean that drivers do nothave to take notice of other vehicles. Drivers must not only observe automobiles, but also motorcycles
and bicycles, and must not forget to check to confirm that it is safe before passing through them.

Natsumi Oshima

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

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●フェイスブック https://www.facebook.com/itarda.or
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

ITARDA INFORMATION no.119

つくば 交通事故調査事務所

ITARDA INFORMATION
交通事故分析レポート No.119lSpeciafeaturePreventing angle collision accidents
involving elderly drivers~ Particular caution is needed at non-signalized intersections ~Single vehicle collisions

3％

Pedestrianvehicle collisions

12％

28
12

住 友 水 道 橋 ビル８ 階■Especially for intersections with two broad roads:
・ Numerous vehicles pass through broad intersections which increases the risk of accidents. Drivers
must not forget to check to confirm that it is safe with regard to other vehicles traveling from both left
and right sides before passing through intersections.

No.119

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■When passing through intersections:・ Drivers must always strictly comply with temporary stops. Since there is the possibility that drivers may
carelessly overlook road signposts and road markings, they must always pay particular attention when
passing through intersections.
・ Even if a driver temporarily stops or decelerates, there is still the possibility that they have failed toproperly check for other vehicles. Drivers must not be content to just temporarily stop at the stop line.
They must endeavor to come to a stop once again at a point where they can see into the intersection
and check to confirm that it is safe, and also pass through at a speed that is sufficiently safe.

ITARDA INFORMATIONAs we have seen thus far, accidents involving elderly drivers have the following characteristics.
■ As people grow older, they become increasingly likely to cause an angle collision accident.
■ Angle collision accidents mainly occur at intersections, with approximately 65% of themconcentrated at non-signalized intersections.

交通事故分析レポート

5 Conclusion

イタルダ インフォメーション

Other vehiclevehicle collisions

31％

Angle collisions

No. of accidents
involving elderly
drivers from2013 - 2015
Total 214,382

30％

Rear-end collisions

24％

Fig. 1. Percentage of accidents by type of accident(Accidents where the primary party aged 65 or over is the driverof a private passenger vehicle; 2013 - 2015)

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l
SpeciafeaturePreventing angle collision accidents involving elderly drivers~ Particular caution is needed at non-signalized intersections ~ITARDA INFORMATION no.119

Characteristics of angle collision accidents

1 Introduction

3 involving elderly drivers

In 2014, the people referred to as “baby boomers” turned 65 years or older. In 2016, the population of elderly
people in Japan reached approximately 34 million, with their share of the total population marking a record high of
27.3%. There has been a steady rise in the number of elderly people with driver’s licenses that has followed theincrease in the elderly population, and it is becoming increasingly commonplace to see elderly people driving
vehicles in their day-to-day lives.
Yet at the same time, traffic accidents involving elderly drivers have come to pose a major social problem in recent
years. Automobiles are now a means of daily transport that elderly people could not do without. But conversely, it issaid that the decline of physical function as people age could potentially exert a grave influence on their driving
ability, and there is likely no shortage of elderly people and members of their families who feel anxious over having
elderly people driving on a daily basis.
Therefore, in this issue of ITARDA Information we will deal with traffic accidents involving elderly drivers. We will
discuss the extent to which angle collision accidents occur and introduce characteristics of them, as these areaccidents that are particularly common among elderly people. In addition, we will also consider points that meritattention for the sake of preventing such accidents.

Fig. 3 shows a c ompar ison of t he perc ent age ofaccidents by type of accident and by age bracket over athree-year period from 2013 - 2015. Rear-end collision
accidents are most prevalent among drivers 64 andunder at 42% of the total, with angle collision accidents
accounting for 23%. On the other hand, rear-end collision
accidents among elderly drivers are low at 24%, with
angle c ollision ac c ident s relatively high at 3 0% .
Apparently, compared with non-elderly drivers, elderly
drivers tend to be more likely to cause angle collision
accidents.
Now then, in what sorts of locations do these angle
collision accidents occur?

This report will primarily focus on automobile accidents that occur in everyday life, and so it will investigate andanalyze accidents where the primary party was the driver of a private passenger vehicle (accidents where theprimary party was operating a commercial passenger vehicle, truck, motorcycle / bicycle, and so on were excluded;
cases where the private passenger vehicle was a rental car or school bus or the like were also not included).

Single vehicle collisions

12%

500,000

10%

400,000

8%

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

0%
2003

0
2002

2%

2001

100,000

2000

4%

1999

200,000

1998

6%

1997

300,000

1996

No. of traﬃc accidents

600,000

Percentage of accidents involving elderly drivers

14%

Fig. 2. Trends in the number of traffic accidents and the percentageof accidents involving elderly drivers (1996-2015)
ITARDA INFORMATION no.119

75 or over
65 - 74
55 - 64
45 - 54
35 - 44
25 - 34
24 or under
Percentage
for 65 - 74
Percentage
for 75 or over

80%

4％

12％

11％

31％

31％

24％

24％

30％

30％

65 - 74

75 or over

24％

70%
60%
50%
40%

42％

Pedestrian-vehicle collisions
Other vehicle-vehicle collisions
Rear-end collisions

20%
10%
0%

2 Extent to which accidents involving elderly drivers occur

700,000

8％

90%

3％

30%

Angle collisions

Fig. 2 shows trends in the number of traffic accidents that have occurred in the 20-year span from 1996 to 2015,
and indicates the percentage of accidents caused by elderly drivers aged 65 or over. The number of accidents
peaked in 2014, and has been falling year by year since then, with a major causal factor behind this being the factthat accidents by drivers aged 64 and under have been falling. The number of accidents caused by elderly drivers
has remained largely unchanged. For this reason, the percentage of accidents involving elderly drivers out of allaccidents has continued climbing, and accounted for nearly 20% of the total in 2015. The percentage of accidents
caused by drivers between the ages of 65 - 74 in particular saw an especially substantial increase starting fromaround 2012 due to the increase in the elderly population from the people referred to as “baby boomers” reaching
the age of 65, as mentioned at the beginning.

2％

100%

23％
64 or underFig. 3. Percentage of accidents
by type of accident (2013 - 2015)
General traﬃc locations
Fig. 4 shows percentages for the types of location where
angle collisions involving elderly drivers occur. An
ove r w h e l m i n g m a j o r i t y o c c u r a t n o n - s i g n a l i ze dintersections accounting for approximately 65% of thetotal accidents. Since non-signalized intersections lacktraffic regulations via a traffic signal, the driver must
make the decision to proceed into the intersection or tocome to a stop on their own. As such, compared withsignalized intersections they contain numerous subjects
for which safety must be confirmed. Moreover, in manycases there are impairments to the driver’s vision suchas roadside structures, walls, and trees and shrubs,
requiring them to more carefully check to confirm that it
is safe. For these reasons, non-signalized intersections
constitute an environment in which it is extremely likelythat angle collision accidents will occur.

2％

Uninterrupted
road sections

15％

Angle collision
Signalized
accidents
involvingintersections
elderly drivers
Non-signalizedintersections

18％

65％

Fig. 4. Percentage of angle collision accidents
by type of location(where the primary party is 65 years or over; 2013 - 2015)

ITARDA INFORMATION no.119lSpeciafeaturePreventing angle collision accidents involving elderly drivers~ Particular caution is needed at non-signalized intersections ~ITARDA INFORMATION no.119

Characteristics of angle collision accidents

1 Introduction

3 involving elderly drivers

In 2014, the people referred to as “baby boomers” turned 65 years or older. In 2016, the population of elderly
people in Japan reached approximately 34 million, with their share of the total population marking a record high of
27.3%. There has been a steady rise in the number of elderly people with driver’s licenses that has followed theincrease in the elderly population, and it is becoming increasingly commonplace to see elderly people driving
vehicles in their day-to-day lives.
Yet at the same time, traffic accidents involving elderly drivers have come to pose a major social problem in recent
years. Automobiles are now a means of daily transport that elderly people could not do without. But conversely, it issaid that the decline of physical function as people age could potentially exert a grave influence on their driving
ability, and there is likely no shortage of elderly people and members of their families who feel anxious over having
elderly people driving on a daily basis.
Therefore, in this issue of ITARDA Information we will deal with traffic accidents involving elderly drivers. We will
discuss the extent to which angle collision accidents occur and introduce characteristics of them, as these areaccidents that are particularly common among elderly people. In addition, we will also consider points that meritattention for the sake of preventing such accidents.

Fig. 3 shows a c ompar ison of t he perc ent age ofaccidents by type of accident and by age bracket over athree-year period from 2013 - 2015. Rear-end collision
accidents are most prevalent among drivers 64 andunder at 42% of the total, with angle collision accidents
accounting for 23%. On the other hand, rear-end collision
accidents among elderly drivers are low at 24%, with
angle c ollision ac c ident s relatively high at 3 0% .
Apparently, compared with non-elderly drivers, elderly
drivers tend to be more likely to cause angle collision
accidents.
Now then, in what sorts of locations do these angle
collision accidents occur?

This report will primarily focus on automobile accidents that occur in everyday life, and so it will investigate andanalyze accidents where the primary party was the driver of a private passenger vehicle (accidents where theprimary party was operating a commercial passenger vehicle, truck, motorcycle / bicycle, and so on were excluded;
cases where the private passenger vehicle was a rental car or school bus or the like were also not included).

Single vehicle collisions

12%

500,000

10%

400,000

8%

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

0%
2003

0
2002

2%

2001

100,000

2000

4%

1999

200,000

1998

6%

1997

300,000

1996

No. of traﬃc accidents

600,000

Percentage of accidents involving elderly drivers

14%

Fig. 2. Trends in the number of traffic accidents and the percentageof accidents involving elderly drivers (1996-2015)
ITARDA INFORMATION no.119

75 or over
65 - 74
55 - 64
45 - 54
35 - 44
25 - 34
24 or under
Percentage
for 65 - 74
Percentage
for 75 or over

80%

4％

12％

11％

31％

31％

24％

24％

30％

30％

65 - 74

75 or over

24％

70%
60%
50%
40%

42％

Pedestrian-vehicle collisions
Other vehicle-vehicle collisions
Rear-end collisions

20%
10%
0%

2 Extent to which accidents involving elderly drivers occur

700,000

8％

90%

3％

30%

Angle collisions

Fig. 2 shows trends in the number of traffic accidents that have occurred in the 20-year span from 1996 to 2015,
and indicates the percentage of accidents caused by elderly drivers aged 65 or over. The number of accidents
peaked in 2014, and has been falling year by year since then, with a major causal factor behind this being the factthat accidents by drivers aged 64 and under have been falling. The number of accidents caused by elderly drivers
has remained largely unchanged. For this reason, the percentage of accidents involving elderly drivers out of allaccidents has continued climbing, and accounted for nearly 20% of the total in 2015. The percentage of accidents
caused by drivers between the ages of 65 - 74 in particular saw an especially substantial increase starting fromaround 2012 due to the increase in the elderly population from the people referred to as “baby boomers” reaching
the age of 65, as mentioned at the beginning.

2％

100%

23％
64 or underFig. 3. Percentage of accidents
by type of accident (2013 - 2015)
General traﬃc locations
Fig. 4 shows percentages for the types of location where
angle collisions involving elderly drivers occur. An
ove r w h e l m i n g m a j o r i t y o c c u r a t n o n - s i g n a l i ze dintersections accounting for approximately 65% of thetotal accidents. Since non-signalized intersections lacktraffic regulations via a traffic signal, the driver must
make the decision to proceed into the intersection or tocome to a stop on their own. As such, compared withsignalized intersections they contain numerous subjects
for which safety must be confirmed. Moreover, in manycases there are impairments to the driver’s vision suchas roadside structures, walls, and trees and shrubs,
requiring them to more carefully check to confirm that it
is safe. For these reasons, non-signalized intersections
constitute an environment in which it is extremely likelythat angle collision accidents will occur.

2％

Uninterrupted
road sections

15％

Angle collision
Signalized
accidents
involvingintersections
elderly drivers
Non-signalizedintersections

18％

65％

Fig. 4. Percentage of angle collision accidents
by type of location(where the primary party is 65 years or over; 2013 - 2015)

ITARDA INFORMATION no.119lSpeciafeaturePreventing angle collision accidents involving elderly drivers~ Particular caution is needed at non-signalized intersections ~ITARDA INFORMATION no.119

Characteristics of angle collision accidents involving

4 elderly drivers in non-signalized intersections

Violation of the mandate toproceed safely throughintersections

Failing to temporarily stopat designated locations, etc.

Obstructing the right-of-way

Violations in reduced-speed sections

Violation of mandatory
safe driving

90%

1％

1％

1％

24％

27％

30％

80%
70%

6％

60%
50%

4％

3％

16％

16％

15％

5％

5％

6％

46％

44％

20%

47％

0%

64 or under

65 - 74

75 or over(4) Two highways

When the primary party is entering the intersection
from a highway and the secondary party
is entering it from a community road

When both intersecting roads are highways

100%
90%

15％

14％

14％

80%

9％

9％

9％

70%

9％

8％

7％

32％

30％

Other driver

60%
50%

33％

40%

4％

10%
0%

30％

4％

32％

Fig. 7. Intersection size classifications* For this report, the decision was made to perform the analysis by ﬁrst deﬁning roads
with a road width of no more than 5.5m as “community roads” and those of 5.5m
or greater as “highways” based on the categories for Road Traﬃc Accident Statistics.

25％

65 - 74

28％

9％

37％

40%

60%

80%

35％
0%

20%
(1) Two community roads

64 or under

Other driver

4％(2) Community road- Highway(3) Highway- Community road

100%(4) Two highways

75 or overFig. 6. Percentage of angle collision
accidents by type of movement(at non-signalized intersections; 2013 - 2015)
ITARDA INFORMATION no.119(3) Highway - Community road

Elderly driverMoving straight- decelerating

Other driver

Elderly driverTurning left

When the primary party is entering the intersection
from a community road and the secondary party
is entering it from a highway

Other driver

10%

20%
Moving straight- constant speed
Moving straight- accelerating
Starting up

When both intersecting roads arecommunity roads

30%

30%

Turning right(2) Community road - Highway

40%

Fig. 5. Percentage of angle collision
accidents by type of legal violation(non-signalized intersections; 2013 - 2015)
Next, Fig. 6 shows a comparison of the percentage ofaccidents by type of movement for angle collision accidents
at non-signalized intersections and by age bracket. Thisreveals that the older the driver the higher the percentage for
accidents that occur when starting up. Conceivably, angle
collision accidents when starting up include instances wherea driver temporarily stops before advancing into theintersection, yet despite this when they then start up theycollide with another vehicle that is coming in from a crossstreet. One factor behind the increase in such accidents isbelieved to be the effects from the decline in cognitive
function and judgment function due to aging. This in turnrenders elderly drivers unable to recognize other vehicles
even if they check to confirm safety, or to predict their
movement even if they do recognize them.

(1) Two community roads

Elderly driver

Other violations

100%

Elderly driver

Here, we will take a look at the characteristic s ofnon-signalized intersections, where angle collision accidents
involving elderly drivers are particularly likely to occur.
Fig. 5 shows a comparison of the percentage of accidents
by type of legal violation for angle collision accidents at
non-signalized intersections and by age bracket. The mostcommon type for each age bracket is violation of mandatory
safe driving, though the percentage for this type decreases
as one’s age increases. On the other hand, the percentageof accidents from failing to temporarily stop increases as one
ages, and it is one of the factors that increases the likelihoodof elderly drivers getting into angle collision accidents at
non-signalized intersections. It is believed that this increasein elderly drivers failing to temporarily stop is backed by anincrease in elderly drivers overlooking road signposts androad markings, as well as the rise in cases in which they fail
to come to a complete stop before accelerating once more.

Next, we would like to subdivide intersection size into the following four categories based on road width, and take a lookat characteristics for each of them in order to clarify the causal factors for angle collision accidents at non-signalizedintersections in greater detail (Fig. 7). The percentage of angle collision accidents that occur in each intersection sizeclassification is shown in Fig. 8.

Fig. 8. Percentage of angle collision accidents by intersection size classification(at non-signalized intersections with a primary party of 65 years or over; 2013 - 2015)
ITARDA INFORMATION no.119lSpeciafeaturePreventing angle collision accidents involving elderly drivers~ Particular caution is needed at non-signalized intersections ~ITARDA INFORMATION no.119

Characteristics of angle collision accidents involving

4 elderly drivers in non-signalized intersections

Violation of the mandate toproceed safely throughintersections

Failing to temporarily stopat designated locations, etc.

Obstructing the right-of-way

Violations in reduced-speed sections

Violation of mandatory
safe driving

90%

1％

1％

1％

24％

27％

30％

80%
70%

6％

60%
50%

4％

3％

16％

16％

15％

5％

5％

6％

46％

44％

20%

47％

0%

64 or under

65 - 74

75 or over(4) Two highways

When the primary party is entering the intersection
from a highway and the secondary party
is entering it from a community road

When both intersecting roads are highways

100%
90%

15％

14％

14％

80%

9％

9％

9％

70%

9％

8％

7％

32％

30％

Other driver

60%
50%

33％

40%

4％

10%
0%

30％

4％

32％

Fig. 7. Intersection size classifications* For this report, the decision was made to perform the analysis by ﬁrst deﬁning roads
with a road width of no more than 5.5m as “community roads” and those of 5.5m
or greater as “highways” based on the categories for Road Traﬃc Accident Statistics.

25％

65 - 74

28％

9％

37％

40%

60%

80%

35％
0%

20%
(1) Two community roads

64 or under

Other driver

4％(2) Community road- Highway(3) Highway- Community road

100%(4) Two highways

75 or overFig. 6. Percentage of angle collision
accidents by type of movement(at non-signalized intersections; 2013 - 2015)
ITARDA INFORMATION no.119(3) Highway - Community road

Elderly driverMoving straight- decelerating

Other driver

Elderly driverTurning left

When the primary party is entering the intersection
from a community road and the secondary party
is entering it from a highway

Other driver

10%

20%
Moving straight- constant speed
Moving straight- accelerating
Starting up

When both intersecting roads arecommunity roads

30%

30%

Turning right(2) Community road - Highway

40%

Fig. 5. Percentage of angle collision
accidents by type of legal violation(non-signalized intersections; 2013 - 2015)
Next, Fig. 6 shows a comparison of the percentage ofaccidents by type of movement for angle collision accidents
at non-signalized intersections and by age bracket. Thisreveals that the older the driver the higher the percentage for
accidents that occur when starting up. Conceivably, angle
collision accidents when starting up include instances wherea driver temporarily stops before advancing into theintersection, yet despite this when they then start up theycollide with another vehicle that is coming in from a crossstreet. One factor behind the increase in such accidents isbelieved to be the effects from the decline in cognitive
function and judgment function due to aging. This in turnrenders elderly drivers unable to recognize other vehicles
even if they check to confirm safety, or to predict their
movement even if they do recognize them.

(1) Two community roads

Elderly driver

Other violations

100%

Elderly driver

Here, we will take a look at the characteristic s ofnon-signalized intersections, where angle collision accidents
involving elderly drivers are particularly likely to occur.
Fig. 5 shows a comparison of the percentage of accidents
by type of legal violation for angle collision accidents at
non-signalized intersections and by age bracket. The mostcommon type for each age bracket is violation of mandatory
safe driving, though the percentage for this type decreases
as one’s age increases. On the other hand, the percentageof accidents from failing to temporarily stop increases as one
ages, and it is one of the factors that increases the likelihoodof elderly drivers getting into angle collision accidents at
non-signalized intersections. It is believed that this increasein elderly drivers failing to temporarily stop is backed by anincrease in elderly drivers overlooking road signposts androad markings, as well as the rise in cases in which they fail
to come to a complete stop before accelerating once more.

Next, we would like to subdivide intersection size into the following four categories based on road width, and take a lookat characteristics for each of them in order to clarify the causal factors for angle collision accidents at non-signalizedintersections in greater detail (Fig. 7). The percentage of angle collision accidents that occur in each intersection sizeclassification is shown in Fig. 8.

Fig. 8. Percentage of angle collision accidents by intersection size classification(at non-signalized intersections with a primary party of 65 years or over; 2013 - 2015)
ITARDA INFORMATION no.119lSpeciafeaturePreventing angle collision accidents involving elderly drivers~ Particular caution is needed at non-signalized intersections ~ITARDA INFORMATION no.119■Angle collision accidents in non-signalized intersections at (3) Highway - Community road

■Angle collision accidents in non-signalized intersections at (1) Two community roads
100%

1％

0.4％

0.4％

98%
96%
94%

8％

10％

7％

92%
90%
88%
86%
84%

91％

90％

93％

Non-signalized intersections at (1) Two community roads are
distributed in large numbers along the complicated networkof roads and back alleys in residential areas. Therefore,
consideration has been given to the possibility that poor
visibility from road-side structures, walls, and trees andshrubs could serve as a causal factor behind angle collision
accidents. Therefore, Fig. 9 shows a comparison of thepercentage of accidents by type of road environmental
factors and by age bracket. As people get older, thepercentage of accidents for which it was determined thatthey had a visual impairment tends to decline, and make up
no more than 10% of the total. In other words, the fact thatelderly drivers end up causing angle collision accidents in
non-signalized intersections at (1) Two community roads is
not necessarily influenced by visual impairments. Rather, itis thought to show the rise in cases in which they cause
accidents even in intersections with good visibility as a resultof the declining cognitive function resulting from aging.

82%
80%

Visual impairment
65 - 74

75 or over

90%
80%

43％

70%

13％

60%
50%
40%

15％

13％

30%
20%

0%

No road environmental factors

Age bracket of the primary party

48％

32％

55％
37％

43％

Non-signalized intersections at (3) Highway - Community
road represent a configuration whereby the primary party is
on a broad highway, that receives inflows of traffic fromnarrow community roads. This configuration is characterized
by the fact that the side the primary party is entering from isoftentimes the road with right-of-way. As such, cases where
they become the primary party (defined as the party thatbears the heavier responsibility when there is a difference inthe level of errors between parties) when an accident
occurs, are rare. Fig. 11 shows a comparison of thepercentage of accidents by type of secondary party and by
age bracket, which reveals a tendency for there to be alarger percentage of vehicle-vehicle accidents the older one
gets. This is believed to indicate an increase in cases
whereby elderly drivers cause an accident because they
were unable to recognize even vehicles with large bodies asa result of declining cognitive function resulting from aging.
Vehicle-bicycle

10%

Other road environmental factors

64 or under

100%

Vehicle-motorcycle
64 or under

65 - 74

75 or over

Vehicle-vehicle

Age bracket of the primary party

Fig. 9. Percentage of angle collision accidents
by type of road environmental factor (2013 - 2015)

Fig. 11. Percentage of angle collision accidents
by type of secondary party (2013 - 2015)■Angle collision accidents in non-signalized intersections at (2) Community road - Highway■Angle collision accidents in non-signalized intersections at (4) Two highways

45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
10km/h 20km/h 30km/h 40km/h 50km/h 60km/h Overor less or less or less or less or less or less 60km/h

Non-signalized intersections at (2) Community road Highway consist of a configuration whereby primary parties
advance from narrow community roads onto broad
highways. Presumably, cases in which drivers neglect tocheck to confirm safety, such as by temporarily stopping or
decelerating decrease. Conversely, as the road the driver isentering is broad, they must simultaneously check forvehicles traveling from both left and right sides. Fig. 10shows a comparison of the percentage of accidents by thedanger perception speed (DPS) of the secondary party, theparty that the elderly driver must check on, and by age
bracket. This shows that as one ages the graph moves
further to the right and the percentage of accidents where
there is a rapid DPS of the secondary party increases. This
indicates an increase in cases where elderly drivers are nolonger able to accurately recognize the speed at which othervehicles are traveling as a result of declining cognitive
function due to aging, or cases where drivers are no longer
able to properly determine whether they should start up or
wait for other vehicles to pass by according to the speed atwhich other vehicles are traveling and their distance.

DPS of the secondary party

Fig. 10. Percentage of angle collision accidents
by DPS of the secondary party(when the secondary party is driving
a moped or larger vehicle; 2013 - 2015)
ITARDA INFORMATION no.119

64 or under

65 - 74

75 or over

100%
90%

16％

15％

15％

45％

45％

40％

40％

80%
70%
60%

46％

50%
40%
30%
20%

38％

10%
0%

65 - 74
75 or overAge bracket of the primary party

64 or underFig. 12. Percentage of angle collision accidents
by direction of motion of the secondary party(when the primary party is moving straight ahead;2013 - 2015)

The non-signalized intersections at (4) Two highways feature
numerous opportunities for complexly intertwined roadways
in the anticipation that they will have a certain volume oftraffic, making these accident-prone environments. This isindicated by the fact that this configuration has the highest
percentage of angle collision accidents by size classification
for non-signalized intersections seen in Fig. 8 above. Fig. 12shows a comparison of the percentages of accidents bydirection of motion of the secondary party and by age
bracket. As people grow older, the percentage of accidents
in which the secondary party is passing through from theright-hand side tends to increase. In other words, there is anincrease in cases in which accidents are caused from thenear lane of the intersection. In general, people tend tooverlook checking to confirm safety when it comes tovehicles traveling in the far lane when they pull out into
intersections. But this is thought to indicate that the decline
in cognitive functions resulting from aging increases cases inwhich they cause accidents without even recognizing that
there is a vehicle traveling in the lane close to them.
Other
From left to right
From right to left

ITARDA INFORMATION no.119lSpeciafeaturePreventing angle collision accidents involving elderly drivers~ Particular caution is needed at non-signalized intersections ~ITARDA INFORMATION no.119■Angle collision accidents in non-signalized intersections at (3) Highway - Community road

■Angle collision accidents in non-signalized intersections at (1) Two community roads
100%

1％

0.4％

0.4％

98%
96%
94%

8％

10％

7％

92%
90%
88%
86%
84%

91％

90％

93％

Non-signalized intersections at (1) Two community roads are
distributed in large numbers along the complicated networkof roads and back alleys in residential areas. Therefore,
consideration has been given to the possibility that poor
visibility from road-side structures, walls, and trees andshrubs could serve as a causal factor behind angle collision
accidents. Therefore, Fig. 9 shows a comparison of thepercentage of accidents by type of road environmental
factors and by age bracket. As people get older, thepercentage of accidents for which it was determined thatthey had a visual impairment tends to decline, and make up
no more than 10% of the total. In other words, the fact thatelderly drivers end up causing angle collision accidents in
non-signalized intersections at (1) Two community roads is
not necessarily influenced by visual impairments. Rather, itis thought to show the rise in cases in which they cause
accidents even in intersections with good visibility as a resultof the declining cognitive function resulting from aging.

82%
80%

Visual impairment
65 - 74

75 or over

90%
80%

43％

70%

13％

60%
50%
40%

15％

13％

30%
20%

0%

No road environmental factors

Age bracket of the primary party

48％

32％

55％
37％

43％

Non-signalized intersections at (3) Highway - Community
road represent a configuration whereby the primary party is
on a broad highway, that receives inflows of traffic fromnarrow community roads. This configuration is characterized
by the fact that the side the primary party is entering from isoftentimes the road with right-of-way. As such, cases where
they become the primary party (defined as the party thatbears the heavier responsibility when there is a difference inthe level of errors between parties) when an accident
occurs, are rare. Fig. 11 shows a comparison of thepercentage of accidents by type of secondary party and by
age bracket, which reveals a tendency for there to be alarger percentage of vehicle-vehicle accidents the older one
gets. This is believed to indicate an increase in cases
whereby elderly drivers cause an accident because they
were unable to recognize even vehicles with large bodies asa result of declining cognitive function resulting from aging.
Vehicle-bicycle

10%

Other road environmental factors

64 or under

100%

Vehicle-motorcycle
64 or under

65 - 74

75 or over

Vehicle-vehicle

Age bracket of the primary party

Fig. 9. Percentage of angle collision accidents
by type of road environmental factor (2013 - 2015)

Fig. 11. Percentage of angle collision accidents
by type of secondary party (2013 - 2015)■Angle collision accidents in non-signalized intersections at (2) Community road - Highway■Angle collision accidents in non-signalized intersections at (4) Two highways

45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
10km/h 20km/h 30km/h 40km/h 50km/h 60km/h Overor less or less or less or less or less or less 60km/h

Non-signalized intersections at (2) Community road Highway consist of a configuration whereby primary parties
advance from narrow community roads onto broad
highways. Presumably, cases in which drivers neglect tocheck to confirm safety, such as by temporarily stopping or
decelerating decrease. Conversely, as the road the driver isentering is broad, they must simultaneously check forvehicles traveling from both left and right sides. Fig. 10shows a comparison of the percentage of accidents by thedanger perception speed (DPS) of the secondary party, theparty that the elderly driver must check on, and by age
bracket. This shows that as one ages the graph moves
further to the right and the percentage of accidents where
there is a rapid DPS of the secondary party increases. This
indicates an increase in cases where elderly drivers are nolonger able to accurately recognize the speed at which othervehicles are traveling as a result of declining cognitive
function due to aging, or cases where drivers are no longer
able to properly determine whether they should start up or
wait for other vehicles to pass by according to the speed atwhich other vehicles are traveling and their distance.

DPS of the secondary party

Fig. 10. Percentage of angle collision accidents
by DPS of the secondary party(when the secondary party is driving
a moped or larger vehicle; 2013 - 2015)
ITARDA INFORMATION no.119

64 or under

65 - 74

75 or over

100%
90%

16％

15％

15％

45％

45％

40％

40％

80%
70%
60%

46％

50%
40%
30%
20%

38％

10%
0%

65 - 74
75 or overAge bracket of the primary party

64 or underFig. 12. Percentage of angle collision accidents
by direction of motion of the secondary party(when the primary party is moving straight ahead;2013 - 2015)

The non-signalized intersections at (4) Two highways feature
numerous opportunities for complexly intertwined roadways
in the anticipation that they will have a certain volume oftraffic, making these accident-prone environments. This isindicated by the fact that this configuration has the highest
percentage of angle collision accidents by size classification
for non-signalized intersections seen in Fig. 8 above. Fig. 12shows a comparison of the percentages of accidents bydirection of motion of the secondary party and by age
bracket. As people grow older, the percentage of accidents
in which the secondary party is passing through from theright-hand side tends to increase. In other words, there is anincrease in cases in which accidents are caused from thenear lane of the intersection. In general, people tend tooverlook checking to confirm safety when it comes tovehicles traveling in the far lane when they pull out into
intersections. But this is thought to indicate that the decline
in cognitive functions resulting from aging increases cases inwhich they cause accidents without even recognizing that
there is a vehicle traveling in the lane close to them.
Other
From left to right
From right to left

ITARDA INFORMATION no.119

Moreover, angle collision accidents at non-signalized intersections involving elderly drivers have thefollowing characteristics.
■ As people grow older, the percentage of accidents caused by a “failure to temporarily stop”
increases.
■ As people grow older, the percentage of accidents “when starting up” increases.
■ The following characteristics depend on the size of the intersection.
(1) At non-signalized intersections with two community roads, the percentage of accidents caused
by impaired visibility decreases.
(2) At non-signalized intersections with community road - highway, the percentage of accidents
with vehicles traveling rapidly increases.
(3) At non-signalized intersections with highway - communit y road, the percentage ofvehicle-vehicle accidents increases.
(4) At non-signalized intersections with two highways, the percentage of accidents with vehicles
traveling from the right-hand side increases.
In addition, it is believed that driving while taking heed of the following points is an effective way of
preventing angle collision accidents at non-signalized intersections.

■Especially for intersections with two narrow roads:
・ Even if an intersection has good visibility and an open field of view, drivers must not forget to check to
confirm that it is safe when passing through. They must pass through intersections with poor visibility
due to road-side structures, trees and shrubs, and other such obstacles by using curved traffic mirrors
etc., and be extra careful.
■Especially for intersections where drivers merge from a narrow road onto a broad road:・ Even when it appears that other vehicles are far away, they could potentially be traveling at a higher
speed than the driver imagines. When there is another vehicle present, drivers must wait for them to go
by before passing through the intersection.
■Especially for intersections with narrow roads when drivers are traveling on a broad road:・ Just because an intersection intersects with a narrow road, does not necessarily mean that drivers do nothave to take notice of other vehicles. Drivers must not only observe automobiles, but also motorcycles
and bicycles, and must not forget to check to confirm that it is safe before passing through them.

Natsumi Oshima

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

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●フェイスブック https://www.facebook.com/itarda.or
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

ITARDA INFORMATION no.119

つくば 交通事故調査事務所

ITARDA INFORMATION
交通事故分析レポート No.119lSpeciafeaturePreventing angle collision accidents
involving elderly drivers~ Particular caution is needed at non-signalized intersections ~Single vehicle collisions

3％

Pedestrianvehicle collisions

12％

28
12

住 友 水 道 橋 ビル８ 階■Especially for intersections with two broad roads:
・ Numerous vehicles pass through broad intersections which increases the risk of accidents. Drivers
must not forget to check to confirm that it is safe with regard to other vehicles traveling from both left
and right sides before passing through intersections.

No.119

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■When passing through intersections:・ Drivers must always strictly comply with temporary stops. Since there is the possibility that drivers may
carelessly overlook road signposts and road markings, they must always pay particular attention when
passing through intersections.
・ Even if a driver temporarily stops or decelerates, there is still the possibility that they have failed toproperly check for other vehicles. Drivers must not be content to just temporarily stop at the stop line.
They must endeavor to come to a stop once again at a point where they can see into the intersection
and check to confirm that it is safe, and also pass through at a speed that is sufficiently safe.

ITARDA INFORMATIONAs we have seen thus far, accidents involving elderly drivers have the following characteristics.
■ As people grow older, they become increasingly likely to cause an angle collision accident.
■ Angle collision accidents mainly occur at intersections, with approximately 65% of themconcentrated at non-signalized intersections.

交通事故分析レポート

5 Conclusion

イタルダ インフォメーション

Other vehiclevehicle collisions

31％

Angle collisions

No. of accidents
involving elderly
drivers from2013 - 2015
Total 214,382

30％

Rear-end collisions

24％

Fig. 1. Percentage of accidents by type of accident(Accidents where the primary party aged 65 or over is the driverof a private passenger vehicle; 2013 - 2015)

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