ITARDA 22th Work Shop Report2019
22nd Presentation Session for Traffic Accident Investigations, Analysis, and Research

Analysis of the effects of collision damage mitigation brakes(Automatic Emergency Brakes (AEB)) by generation
Naoya Kondo
Researcher, Research Division

1

ITARDA 22th Work Shop Report

1.

Introduction

Collision damage mitigation brakes (Automatic Emergency Brakes (AEB)) are a driving assist system that drivers
rely on to avoid accidents or to mitigate the damage when accidents do occur. They operate by urging the driver tobrake or by undertaking brake control in lieu of the driver in response to errors related to cognition, decision-making,and operation, which are counted among the human factors that serve to cause traffic accidents (Fig. 1).

Beep beep

Beep

Brakes activated!
Assists in applying brake pedal force
Warning via a buzzer and indicator

Fig. 1. Image of an AEB system activating (Source: Suzuki’s homepage)In the initial stages of the dissemination of AEB, the dominant variety consisted of AEB systems that used laser
radar (or millimeter wave radar) as their sensors (hereinafter referred to as the "first generation"). These mainly
served to detect the rear of the four-wheel vehicle out ahead of the vehicle in question, and would activate inconditions where the vehicle speed was between 5 - 30 (5 - 80) km/h. In recent years, AEB equipped with moresophisticated sensors than what were initially disseminated (hereinafter referred to as the "second generation") havebeen making it possible to improve the activation speed and detect pedestrians and other road object. AEB aremainly designed to activate for rear-end collision accidents with four-wheel vehicle and pedestrian-vehicle accidents.
When the proportion of the total number of accidents that these account for where the primary party was driving afour-wheel vehicle is taken into consideration, they were found to account for 47% of casualty accidents and 43%
of fatal accidents over the five-year period from 2014 - 2018 (Figs. 2 and 3). Moreover, recently AEB that can
respond to head-on collisions with four-wheel vehicles and accidents involving collisions between a vehicle turning
right and a vehicle going straight, and that can handle detecting bicycles, have begun to be practically implemented.
As such, the expectations placed on AEB to mitigate the damage from accidents continues to widen in scope.
The objective of this report will be to determine the accident damage mitigation effects for each generation of AEB
systems (first / second generations) by type of accident status and driver’s property for rear-end collision accidents
with four-wheel vehicles and pedestrian-vehicle accidents, and to propose a course of action for further enhancing
their effectiveness.

2

ITARDA 22th Work Shop Report

Casualty accidents

Fatal accidents

Involving a train 0%

Single vehicle accident

Involving a train 0%2%
Pedestrianvehicle
accident

Other vehiclevehicle
accident
43%

Single vehicle
accident
21%

10%

Rear-end
collision with
FWV
37%

Vehicle turning right /vehicle going straight 6%
Head-on collisions 2%

Other vehiclevehicle
accident
20%

Pedestrianvehicle
accident
40%

Vehicle turning right /vehicle going straight 5%
Head-on collisions 11%

Rear-end collision with FWV
3%

N=2,281,108
N=14,814
Figs. 2 / 3: Status of traffic accidents by type of accident(2014 - 2018, primary party driving a four-wheel vehicle)
2.

Analytical methods

Sections 2.1 - 3 calculated the number of accidents per 100,000 vehicles owned by three groups based on the AEB
system status of the primary party's vehicle (first generation-equipped vehicles, second generation-equipped
vehicles, and vehicles without AEB).
2.1. Aggregating the number of accidents
The following guidelines were used to aggregate the number of accidents.
Target years: 2016 - 2018 (three years)
Target vehicles: Vehicle of the primary party that is a privately owned kei sized passenger vehicle with AEB
set up on it (69 models total)
Type of accident (accident details): Rear-end collision accidents with four-wheel vehicles (casualty accidents)
and pedestrian-vehicle accidents (casualty accidents, fatal and serious injury accidents)
This report took accidents in which the primary party was driving a kei sized vehicle as the subject of its analysis.
The accident database that uses information on AEB systems focuses on kei sized vehicle models that went on salein January 2006 and thereafter. Since accidents caused by vehicles sold from 2012 onward, which is when the first
generation AEB systems began to be disseminated to kei sized vehicles in earnest, are included, this offers
conditions conducive to analyzing accidents based on the AEB generation (for medium and small sized vehicles,
the focus was placed on vehicles sold in or after April 2015, the majority of which came outfitted with second
generation AEB).
When it comes to the accident details, most rear-end collisions with a four-wheel vehicle comprise slight injury
accidents, and so the decision was made to look at trends in whether or not accidents occurred from the number ofcasualty accidents. With pedestrian-vehicle accidents, ideally the number of casualty accidents as well as fatal
accidents should be focused on in order to view damage mitigation trends. However, since an adequate number offatal accidents alone could not be obtained, trends with the number of fatal and serious injury accidents wereobserved.
The number of accidents obtained from this aggregation were classified into three groups based on the AEB system

3

ITARDA 22th Work Shop Reportstatus of the primary party's vehicle (first generation-equipped vehicles, second generation-equipped vehicles, andvehicles without AEB). In order to identify the generation of AEB, information on the model of the primary party’s
vehicle and the date of the initial inspection was used. In addition, the following rules were used to sort these.
1) For models on which AEB was equipped in the middle of their sales period, accidents caused by vehicles thatwere registered in the period prior to AEB being equipped on said model were not included in the aggregation.
2)

Regarding models that were sold with both first and second generation AEB, the actual shift in the share ofvehicle registrations from first generation to second generation systems is thought to have happened gradually,
but it was difficult to get a grasp of the actual status of this shift. Therefore, all vehicles that were registered
starting from the next month after second generation AEB was added were regarded as having switched overto the second generation (this was processed by including accidents by first generation vehicles in with someof the accidents caused by second generation vehicles).

2.2. Aggregating the number of vehicles owned
The number of vehicles owned in the middle of the year was used to calculate the number of accidents per 100,000
vehicles owned. The numbers of vehicles owned as of the ends of 2015 - 2018 categorized into the three groups
mentioned above (Table 1) were used to calculate the numbers of vehicles from the middle of the three-year period
from 2016 - 2018 (Table 2). The following rules were used in order to aggregate and categorize the number ofvehicles owned, similar to how the number of accidents was aggregated.
1)
2)

For models on which AEB was equipped in the middle of their sales period, the number of vehicles owned thatwere registered in the period prior to AEB being equipped on said model were not included in this aggregation.
Regarding models that were sold with both first and second generation AEB, all vehicles that were registered
starting from the next month after second generation AEB was added were regarded as having switched overto the second generation.
Table 1. Number of vehicles owned by AEB system status at the end of each year from 2015 – 2018
AEB
Equipped
Not equipped

Specs
First generation
Second generation-

End of 2015
1,894,171
178,978
1,722,532

End of 2016
2,280,620
610,825
2,159,032

End of 2017
2,603,003
1,303,190
2,475,216

End of 2018
2,781,735
2,332,757
2,623,811

Table 2. Number of vehicles owned by AEB system status in the middle of the period
from 2016 - 2018 (total for the three years)
AEB
Equipped
Not equipped

Specs
First generation
Second generation-

Middle of the period
from 2016 - 2018
7,221,576
3,169,883
6,807,420

2.3. Estimating the number of vehicles owned by the driver's age
In order to analyze the number of accidents per 100,000 vehicles owned by the driver's age, the number of vehicles
owned by drivers of each age group ought to be used for the analysis. However, this data is hard to come by. As analternate method, traffic exposure that uses the number of secondary parties (who are not at fault when traffic
accidents occur) was used to estimate the number of vehicles owned by each age group. Specifically, the number of4

ITARDA 22th Work Shop Reportvehicles on the receiving end of a rear-end collision (numbers in the top row of Table 3) driven by drivers not at
fault (secondary party) over the three-year period from 2016 - 2018 corresponds to traffic exposure. The number ofvehicles aggregated in Section 2.2. was distributed according to the composition rate for the number of vehicles by
age group (numbers in the bottom row of Table 3) (Table 4). These figures were used to calculate the number ofaccidents per 100,000 vehicles owned by the driver's age. The traffic exposure is based on the thinking that when
the probability of a single vehicle becoming involved in an accident without the driver being at fault is treated as aconstant, the number of accidents is indicative of the usage frequency for road traffic [Research Material 1].
Table 3. Number of vehicles on the receiving end of a rear-end collision where the driver was not
at fault by AEB system status and driver's age from 2016 - 2018
(upper row: number of vehicles; bottom row: composition rate)
AEB

Specs
First generation

Equipped
Second generation
Not equipped

—

- 29
3,361
20.3
1,397
21.9
3,256
20.4

30 - 49
7,482
45.2
2,843
44.5
7,425
46.5

50 - 64
4,000
24.2
1,528
23.9
3,653
22.9

65 - 74
1,375
8.3
501
7.8
1,312
8.2

75 341
2.1
114
1.8
309
1.9

Table 4. Estimated number of vehicles by AEB system status and driver's age from the middleof the period from 2016 – 2018
AEB
Equipped
Not equipped

3.

Specs
First generation
Second generation—- 29
1,465,772
693,769
1,389,217

30 - 49
3,262,989
1,411,872
3,167,97850 - 64
1,744,447
758,825
1,558,603

65 - 74
599,654248,803559,783

75 148,714
56,614
131,839

Results and considerations

3.1 Rear-end collisions with a four-wheel vehicle (casualty accidents)
Fig. 4 shows the number of casualty accidents involving rear-end collisions with a four-wheel vehicle per 100,000
vehicles owned by group. The blue indicates the number of accidents by vehicles without AEB, the yellow is thenumber by vehicles with first generation AEB, and the orange is the number by vehicles with second generation
AEB. The numbers at the top of the graphs indicate the rate of decline from first generation and second generation
vehicles versus those without AEB. The two (one) asterisks at the top of the graphs indicate that a significance levelof 1% (5%) or over was maintained in statistical tests of the difference in the ratio between the two groups. Graphs
for which significance could not be obtained are indicated in gray. The listing of the rate of decline and significancelevel follows the same standards in the subsequent graphs as well. As for the error bar, when the distribution of theaverage values has been assumed to be identical to the F distribution, then this indicates a confidence interval of
99%. This reveals that the number of accidents declines significantly with vehicles equipped with first and second
generation AEB versus those without it. The rate of decline is higher with the second generation than with the first
generation.
The number of casualty accidents per 100,000 vehicles owned is shown in Fig. 5 by whether the accident occurred

5

ITARDA 22th Work Shop Reportduring the day or at night. The number declined significantly for both vehicles with first generation and second
generation AEB, with the rate of decline higher for vehicles with the first generation over the second generation

Without
AEB

SecondgenerationFirst
generation

Without
AEB

Number of casualty accidents per
100,000 vehicles owned

Number of casualty accidents per
100,000 vehicles owned

both during the day and at night.

Day

SecondFirst
generation generation

Fig. 4. Number of casualty accidents per 100,000
vehicles owned

Night

Fig. 5. By day / night

Fig. 6 shows the number of casualty accidents per 100,000 vehicles owned by the danger perception speed of the
primary party vehicle. With vehicles with first generation AEB this was primarily in a speed range from 0 - 30km/h,
while for the second generation declines were observed in the speed ranges from 0 - 30km/h, up to 60km/h, andFirst generation

Secondgeneration

Without AEB

Number of casualty accidents per
100,000 vehicles owned

over 61km/h. Since every model of kei sized vehicle with first generation AEB were equipped with laser radar (withan activation speed range of 5 - 30km/h), the effects obtained showed that both the first and second generation werelargely consistent in terms of the specifications for their activation speeds.

Fig. 6. By danger perception speed of the primary party
The number of accidents per 100,000 vehicles owned as classified by the type of movement of the primary party
revealed that going straight and starting up accounted for most types of movement at the time of the accident,
regardless of whether AEB was equipped or not and differences in the specifications (Fig. 7). Next, this will beanalyzed by linking the driving behavior when the accident occurred (when going straight, when starting up) andthe human factors at this time (human error).
Supplementary explanations of the contents of the human factors dealt with in this report are provided in Table 5.
Descriptions concerning the human factor items not dealt with in this report have been omitted.
A graph of the number or accidents per 100,000 vehicles owned by human factor when going straight is shown (Fig.
8). The number of accidents for the three items with the highest composition rates among the human factors (intrinsic

6

ITARDA 22th Work Shop Report

failure to pay attention forward, extrinsic failure to pay attention forward, and failure to observe surrounding traffic
movement when going straight) and for total when going straight have been indicated. The rate of decline for humanfactors that are decreasing over and above the totals for when going straight have been listed in red. The effects
obtained showed that the rate of decline was higher with the second generation compared to with the first acrosseach of the human factors. Since the speed range of vehicles when going straight is spread out across a broad range
from low to high speeds, the assumption is that second generation AEB would be more effective given their broader
activation speed range. One characteristic point is that even under the same category of failure to pay attention
forward, the decline was more significant with an extrinsic failure to pay attention forward than with an intrinsic
failure to pay attention forward. No difference in braking distance arises due to the automatic activation of thebrakes by the AEB, regardless of whether the failure to pay attention forward was due to intrinsic or extrinsic causes.
Therefore, this presumably indicates that with this difference there is a shorter length of time from when the AEB
emits a warning at the state prior to automatically activating the brakes until the driver steps on the brake with an
extrinsic failure to pay attention forward, thus making it easier to avoid accidents (which approximately correlates
to making it easier to cover for errors).
As for the number of accidents by human factor per 100,000 vehicles owned when starting up (Fig. 9), extrinsic
failure to pay attention forward, failure to observe surrounding traffic movement, and operating error account for alarge share of these. A rate of decline was obtained from first generation AEB that is approaching that from thesecond generation. This is presumably because vehicle speed when starting up is often in low speed ranges, making
it easier to receive the effects of both first and second generation AEB.
Table 5: Supplementary explanations for human factors
Human factor

Cognitive
errorsDefinition

Intrinsic failure to
pay attention forward

A failure to pay attention forward due toa psychological or physiological factor

Extrinsic failure to
pay attention forward

Failure to pay attention forward resulting
from motion
Failed to confirm everything possible
despite decelerating to a speed whereconfirmation was possible
Detected (became aware of) the otherparty, but neglected to pay attention to
the movement of said party
Improper operation or hesitating inoperating the vehicle due to surprise

Failure to confirm
safety factors

OperatingerrorsFailure to observe
surrounding traffic
movement
Driving operation
errorsNumber of casualty accidents per
100,000 vehicles owned

Decisionmaking errors

Sample conditions
Dozing off
Lost in thought
Aimless driving
Distracted
Trying to retrieve something
Failure to confirm safety
Inadequate safety
confirmation
Driver thought the other party
would stop and took their eyes
off them
Misapplication of the pedals
Late in applying brakes

Other

Going
straight
Startingup
Without
AEB

First
generation

Secondgeneration

Fig. 7. By type of movement of the primary party

7

Intrinsic
failure to pay
attention
forwardExtrinsic
failure to pay
attention
forwardFailure toobservesurrounding
traffic
movement

Total forwhen goingstraight

Fig. 8. By human factor when going straight

Without
AEB
First
generation
Secondgeneration

Number of casualty accidents per
100,000 vehicles owned

Without
AEB
First
generation
Secondgeneration

Number of casualty accidents per
100,000 vehicles owned

ITARDA 22th Work Shop Report

Extrinsic
failure to pay
attention
forwardFailure toobservesurrounding
traffic
movement

Driving
operation
errorsTotal forwhen startingup

Fig. 9. By human factor when starting up

The number of accidents per 100,000 vehicles owned by the driver's age differs from the results indicated thus far,with the number of vehicles owned by the driver's age obtained from Section 2.3 having been used as the numberof vehicles owned (Fig. 10). Regardless of whether or not the vehicle is equipped with AEB, the overall trend
indicated that young people age 29 and younger and elderly people age 75 and older had a large number of accidents.

- 29

Secondgeneration

Without AEB

First generation

Number of casualty accidents per
100,000 vehicles owned

However, decreases were seen across every age group for both first and second generation AEB.

30 - 49

50 - 64

64 - 74

75 -All ages

Fig. 10. By age of the primary party
As for rear-end collisions with a four-wheel vehicle, the main cases where the effects of AEB were seen have been
compiled into Table 6 by AEB generation. From the accident statuses confirmed for both generations, the accident
damage mitigation effects were found to be greater with the second generation than with the first. The difference inthe rate of decline was particularly pronounced in a speed range of up to 60km/h when viewed by danger perception
speed. When viewed by human factor, the errors mainly covered by the first and second generations were the same.

8

ITARDA 22th Work Shop Report

Table 6. Cases where effects were mainly seen: Rear-end collisions with a four-wheel vehicle
SpecificationsFirst generation

Second generation

Time of day

Day, night

Danger perception speed

0 - 30km/h


0 - 30km/h- 60km/h
61 km/h -When going straight
Type of movement x
Human factors

When starting up

Driver age

Extrinsic failure to pay attention
forwardExtrinsic failure to pay attention
forward, failure to observe surrounding
traffic movement

All age groups

In considering what will be necessary to further improve the effects of AEB in regard to rear-end collision accidents
with four-wheel vehicles, since effects have been observed as things currently stand with accident statuses that
account for a high share of the total, still greater effects could be obtained by improving the basic performance of
AEB. Proposals for improving its basic performance that could be mentioned include improving the detection
accuracy for the vehicles up ahead by adopting 79 GHz millimeter wave radar, or electrifying the brake system inorder to improve braking efficiency.
3.2 Pedestrian-vehicle accidents (casualty accidents, fatal and serious injury accidents)
Figs. 11 and 12 show the number of casualty accidents and the number of fatal and serious injury accidents per
100,000 vehicles owned by group. The blue shows the number of accidents by vehicles without AEB and the orange
shows the number from vehicles with second generation AEB. Vehicles with first generation AEB were unable todetect pedestrians and demonstrated trends similar to vehicles without AEB in terms of their analytical results, andthus were omitted. Vehicles with second generation AEB showed significant declines versus vehicles without AEB
systems for both casualty accidents and fatal and serious injury accidents. Pedestrian-vehicle accidents include
accidents caused by pedestrians rushing out where, even if it is assumed that the AEB was able to detect theFig. 11. Number of casualty accidents per
100,000 vehicles owned

Secondgeneration

Without
AEB

Number of casualty
accidents per 100,000
vehicles owned

Secondgeneration

Without
AEB

Number of casualty
accidents per 100,000
vehicles owned

pedestrian faster to some extent, it was unable to apply the brakes in a physical sense in time to prevent the accident.
This is a point that requires attention. Since it is difficult to isolate out these accidents, they were not categorized
for this report.

Fig. 12. Number of fatal and serious injury
accidents per 100,000 vehicles owned

Figs. 13 and 14 show the number of casualty accidents and the number of fatal and serious injury accidents per
100,000 vehicles owned by the time of day the accident occurred. While casualty accidents declined in both the day
9ITARDA 22th Work Shop Reportand at night, conversely with fatal and serious injury accidents only a significant decrease was observed at night.
There is no information in the macro data on the extent of the illumination from street lamps and the like for
accidents at night. However, with current kei sized vehicles the number of models capable of detecting pedestrians
at night is limited, and so there is the conceivable possibility that other methods besides AEB like automatic high

Day

Night

Fig. 13. Casualty accidents by time of day

Without
AEB
Secondgeneration

Number of fatal and serious injury
accidents per 100,000 vehicles owned

Without
AEB
Secondgeneration

Number of casualty accidents
per 100,000 vehicles owned

beams that activate at nighttime also contribute to reducing accidents at night.

Day

Night

Fig. 14. Fatal and serious injury accidents by time ofday

As for the number of accidents per 100,000 vehicles owned categorized by the type of movement of the primary
party vehicle (Figs. 15 and 16), accidents when going straight or turning right account for the vast majority of bothcasualty accidents and fatal and serious injury accidents, regardless of whether the vehicle was equipped with AEB.
Human factors were linked with this to perform the analysis on accidents when going straight and when turning
Number of fatal and serious injury accidents
per 100,000 vehicles owned

right.
Other

Number of casualty accidents
per 100,000 vehicles owned

Turning left
Starting up
Reversing

Turningright
Startingup

Without
AEB

Secondgeneration

Fig. 15. Casualty accidents by type of movement of
the primary party

Other

Turning left
Starting up
Reversing

Turningright

Startingup

Without
AEB

Secondgeneration

Fig. 16. Fatal and serious injury accidents by type of
movement of the primary party

For the number of accidents per 100,000 vehicles owned by human factor when going straight, for the three itemswith the highest composition ratio (intrinsic failure to pay attention forward, extrinsic failure to pay attention
forward, and failure to confirm safety factors) and for total when going strait were indicated for both casualty
accidents and fatal and serious injury accidents (Figs. 15 and 16). Accidents caused by an intrinsic or extrinsic
failure to pay attention forward had a rate of decline that exceeded the total for accidents when going straight. It is

10

ITARDA 22th Work Shop Reportbelieved that this suggests that errors in situations in which a person is in the field of view of the sensor and driver
but the driver fails to see them can be covered by the AEB. Conversely, with accidents caused by a failure to confirm
safety factors this resulted in a relatively low rate of decline. Accidents caused by a failure to confirm safety factors
include accidents that cannot be covered for by AEB as things currently stand, which is thought to be why they wereless prone to receiving the benefits. Examples of such accidents include cases where a pedestrian moves fromoutside to inside the sensor's field of view, such as when they rush out, or cases where accidents occur when thepedestrian is outside of said field of view.
For the number of accidents per 100,000 vehicles owned by human factor when turning right, the three items withthe highest composition ratio for both casualty accidents and fatal and serious injury accidents were intrinsic failure
to pay attention forward, extrinsic failure to pay attention forward, and failure to confirm safety factors. Failure toconfirm safety factors accounted for the majority, but no significant differences were seen based on whether thevehicle had AEB or not for any of the human factors. This is similar to accidents when going straight, in that it isbelieved that there is a mismatch between the field of view of the vehicle's sensor and the position of the pedestrian,Intrinsic
failure topayattention
forwardExtrinsic
failure topayattention
forwardFailure to Total forwhen
observesurrounding goingstraight
traffic
movement

Fig. 17. Casualty accidents by human factor
when going straight

Without AEB

Second generation

Number of fatal and serious injury accidents
per 100,000 vehicles owned

Without AEB

Second generation

Number of casualty accidents
per 100,000 vehicles owned

and it is thus unable to detect the pedestrian.

Intrinsic
failure topayattention
forwardExtrinsic
failure topayattention
forwardFailure to Total forobservewhensurrounding goingtraffic
straight
movement

Fig. 18. Fatal and serious injury accidents
by human factor when going straight

The number of accidents per 100,000 vehicles owned by type of accident for pedestrian-vehicle accidents(categorized by relative position of the vehicle and the person and the direction of motion of the person; Figs. 19
and 20) reveals a significant decline in accidents under certain conditions. Said conditions include casualty accidents
while the pedestrian is walking facing the vehicle or while walking parallel to the vehicle and other cases where theperson is out ahead of the vehicle, which is to say, often when the person is within the sensor's field of view. On theother hand, for fatal and serious injury accidents there has been a greater decline in accidents while crossing
compared to with casualty accidents. This suggests that there are a certain number of accidents where the AEB was
unable to fully avoid the accident, but was able to mitigate the damage down to a slight injury accident.

11WhileWhile While On roadwalking walking crossing
facing parallel the roadtovehiclevehicleOther

Fig. 19. Casualty accidents
by detailed type of accident

Without AEB

Second generation

Number of fatal and serious injury accidents
per 100,000 vehicles owned

Without AEB

Second generation

Number of casualty accidents
per 100,000 vehicles owned

ITARDA 22th Work Shop Report

While
While While On roadwalking walking crossing
facing parallel the roadtovehiclevehicleOther

Fig. 20. Fatal and serious injury accidents
by detailed type of accident

The number of accidents per 100,000 vehicles owned by the driver's age has shown a tendency towards a larger
number of accidents the higher up in age one goes, with this holding true for both casualty accidents and fatal andserious injury accidents regardless of whether or not the vehicle had AEB (Figs. 21 and 22). There are some agegroups with a limited number of accidents where no significant difference was seen, but on the whole a downward

Fig. 21. Casualty accidents by ageof the primary party

All ages

75 -65 - 74

50 - 64

30 - 49

Without AEB

Second generation- 29

Number of fatal and serious injury accidents
per 100,000 vehicles owned by age

All ages

75 -65 - 74

50 - 64

30 - 49

Without AEB

Second generation- 29

Number of casualty accidents
per 100,000 vehicles owned by age

trajectory was seen across all age groups.

Fig. 22. Fatal and serious injury accidents by age ofthe primary party

With regard to pedestrian-vehicle accidents, cases where the effects were mainly seen were summarized in Table 7.
With second generation AEB, effects were observed in the form of a decline in both pedestrian-vehicle casualty
accidents and fatal and serious injury accidents. When viewed by status, effects were oftentimes noted with cases
where the person is within the sensor's field of view. As for accidents at nighttime, the thinking is that automatic
high beams and other ASV devices could potentially have the effect of mitigating damage.

12

ITARDA 22th Work Shop Report

Table 7. Cases where effects were mainly seen: Rear-end collisions with a four-wheel vehicle

Accident details
Time of day
Type of movement
x Human factors

Casualty accidents

When goingstraight

Day, night(*1)
Intrinsic failure to pay attention forward
Extrinsic failure to pay attention forward

Fatal and serious injury
accidents
Night(*1)


Driver age

All age groups(*2)

Type of accident(person's location,
movement)

While crossing the street, while walking facing the vehicle,
while walking parallel to vehicle, on road

While crossing theroad, on road

With regard to pedestrian-vehicle accidents, when one considers what will be necessary in order to further improvethe effects from AEB systems, it would presumably be beneficial to expand the detection range for pedestrians(particularly around angles). This could be done via the adoption of LiDAR (Light Detection and Ranging) to makeit possible to detect pedestrians located outside of the field of view of the sensors on current vehicles. Conversely,
accidents where the AEB is unable to apply the brakes in time in a physical sense no matter how quickly it detects
the pedestrian cannot be prevented by AEB. As such, the thinking is that it will be necessary to combine it withaccident prevention systems that activate in a quicker time frame than AEB does, such as ITS [Reference Material2], in order to eliminate pedestrian accidents.
Given the current analytical conditions, it was impossible to analyze the results from conditions corresponding to
the conditions in which AEB activate to a certain extent for pedestrian-vehicle accidents compared with rear-end
collision accidents. As such, conceivably there were scenarios in which it was difficult for the effects of AEB to be
become apparent. Presumably, it will be necessary in the future to set in place an environment for analyzing
accidents that would make it possible to analyze the results of ASV, including AEB, in a detailed manner.
4.

Conclusion

This report determined the effects of mitigating the damage from rear-end collision accidents against four-wheel
vehicles and pedestrian-vehicle accidents by the different specification of AEB.
1)

2)

Regarding rear-end collisions with a four-wheel vehicle
Regarding the accident damage mitigation effects, greater effects were obtained with the second generation of
AEB than with the first
Ideally, the effects can be further improved by enhancing the sensitivity and braking efficiency of AEB systems
Regarding pedestrian-vehicle accidents
Second generation AEB systems that can detect pedestrians demonstrated effects in terms of mitigating thedamage from accidents
It will be necessary to develop AEB that can cover pedestrians outside of the field of view of the current sensors
in order to further improve upon their effects
In order to reach zero pedestrian accidents, it will be necessary to combine AEB with accident prevention
systems that activate in a quicker time frame than AEB does

13

ITARDA 22th Work Shop Report[参考資料][1] 西田 泰、他、2012 年、「交通事故分析に基づく交通行動特性の把握手法に関する研究」 (公社)
日本交通政策研究会[2] 大久保 義行、2019 年、「歩行者事故低減歩車間通信技術を用いた安全支援システムの開発」
於 2019 自動車技術会春季大会フォーラム「SIP 第 1 期『自動走行システム』の研究開発成果―SIP-adus
成果報告―」発表資料
パナソニック株式会社 コネクティッドソリューションズ社

14