ITARDA 26th Work Shop Report2023
26th Presentation Session for Traffic Accident Investigations, Analysis, and Research

Fatal accidents involving four-wheeled vehicles and pedestrians and high-performanceheadlights
Shinta Arai
Senior Researcher, Research Division

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ITARDA 26th Work Shop Report

Background and Purpose
Although traffic accident data from 1990 to 2022shows a slight change in the proportion of overall
traffic accident fatalities and injuries due to traffic
accidents at night, this proportion has remained

40%
30%
20%
10%0%
1990年
1990
1992年
1992
1994年
1994
1996年
1996
1998年
1998
2000年
20002002年
2002
2004年
2004
2006年
2006
2008年
2008
2010年
2010
2012年
2012
2014年
2014
2016年
2016
2018年
2018
2020年
2020
2022年
2022

1.

below 30% for roughly the past 15 years (see Fig. 1).
On the other hand, less than 70% of those who diedin traffic accidents while walking involved inFig. 1 Proportion of nighttime traffic accident fatalities or injuries

nighttime accidents (see Fig. 2). This trend has

80%

remained almost constant for 30 years, and contrasts

70%

with the fact that the number of deaths under othercircumstances, such as those involving four-wheeled

60%
50%40%30%

less than 40% over the past 15 years. Although20%

pedestrians may be somewhat difficult to see at night,

10%

Four-wheeled
四輪vehicles
原付Mopeds

0%

Pedestrians
歩⾏者

why exactly do pedestrian deaths account for 70% of
fatalities or injuries at night, which make up less than
30% of all traffic accident fatalities and injuries?
Considering that more than 90% of the parties
involved in fatal pedestrian accidents (involving a
primary and secondary party) are four-wheeledvehicles (see Fig. 3), subsequent analysis wasBicycles
⾃転⾞Fig. 2 Proportion of nighttime traffic accident fatalities by circumstance100%

Four-wheeled vehicles

80%
60%
40%
20%

four-wheeled vehicles and pedestrians (primary and0%

Four-wheeled
四輪vehicles
Mopeds
原付

Motorcycles
⾃動⼆輪
Bicycles
⾃転⾞

1990
1990年
1992
1992年
1994
1994年
1996
1996年
1998
1998年
2000
2000年
2002
2002年
2004
2004年
2006
2006年
2008
2008年
2010
2010年
2012
2012年
2014
2014年
2016
2016年
2018
2018年
2020年
2020
2022年
2022

performed by examining fatal accidents involving
secondary parties).
According to a survey and analysis conducted by
Japan’s National Police Agency

Motorcycles⾃動⼆輪

1990
1990年
1992
1992年
1994
1994年
1996
1996年
1998
1998年
2000
2000年
2002
2002年
2004
2004年
2006
2006年
2008
2008年
2010
2010年
2012
2012年
2014
2014年
2016
2016年
2018
2018年
2020
2020年
2022
2022年

vehicle passengers or bicycle riders, has converged to(1)Fig.3 Proportion of parties involved in fatal pedestrian accidents

in 2016, 56% of(nighttime)

fatal accidents involving four-wheeled vehicles and100%

pedestrians (at night and with the four-wheeled vehicle driving

80%

straight ahead) were more likely to have been avoided had the60%

driver tilted their headlights upwards (by using high beams). The

40%

traffic regulations, etc. And, in the past 10 years, approximately
95% of fatal accidents involving four-wheeled vehicles and20%
0%

2013年
2013
2014年
2014
2015年
2015
2016年
2016
2017
2017年
2018
2018年
2019
2019年
2020
2020年
2021
2021年
2022
2022年

use of high beams has since been promoted through revisions toHeadlights: Downwards
前照灯_下向き
Headlights: Upwards
前照灯_上向き
Auxiliary lights
補助灯
Lights off
消灯

pedestrians (primary and secondary parties) have been caused bydrivers with their headlamps tilted downwards (using only theirlow beams) (see Fig. 4).

2Fig. 4 Headlight direction by proportion

ITARDA 26th Work Shop Report

Based on the above, we conducted our research with the aim of helping to reduce the number of traffic accident
victims by investigating the causes of many nighttime fatal pedestrian accidents and proposing effective ways ofreducing nighttime accidents involving pedestrians.
2.

Methods used
With the proliferation of preventive safety equipment, most new vehicles are now equipped with high-performance headlights (2). The high-performance headlights currently being equipped to many new vehicles comein two types: An auto-switching type that automatically switches the headlights upwards and downwards, and anauto-dimming type that dims the headlights only in the direction of oncoming and preceding vehicles while
controlling light distribution so that the light is directed to other areas as much as possible. Providing that thesesystems function normally, it is highly likely that drivers will be able to avoid collisions in many of the 56%
accidents reported by the National Police Agency. Therefore, if such proliferation of high-performance headlights
were to continue, one can assume that statistically, the effectiveness of such adoption would be evident. That said,
because high-performance headlights are not regulated by laws and many require driver operation to be activated,
they may necessarily not be activated at the time of an accident, nor is there is any obligation for records to be keptof whether the headlights were facing upwards or downwards. Therefore, during our research on this topic, weperformed grouping based on whether or not the vehicle involved in the traffic accident was equipped with highperformance headlights (see Table 1) while making the following assumptions.
Table 1. Vehicle classification by high-performance headlight equipping status
Classification
Standard-equipped ADetails
This includes vehicles with high-performance headlights with functions that
activate automatically and without the need for the driver to take action,
vehicles with high-performance headlights that continue to remain powered on
and activated via use of a dedicated switch that only needs to be turned on
once, vehicles with high-performance headlights that activate only when thehigh-/low-beam switch is set in the low-beam position, and those that activate
regardless of the switch position.

Standard-equipped B

Other than Standard-equipped A above.
This includes vehicles with high-performance headlights that require a
dedicated switch to be turned on in order for them to be powered on, or thosethat only activate when the high-/low-beam switch is set in the high beam
position.

Non-standard-equipped

This applies to vehicles in which high-performance headlights are an option,or in which only some models are equipped with high-performance headlights.

Not equipped

This applies to vehicles not equipped with high-performance headlights

・ In vehicles standard equipped with high-performance headlights, their functionality is activated in a certain
proportion of traffic accidents.
・ A certain proportion is divided into two types depending on whether driver action is necessary for operation.

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ITARDA 26th Work Shop Report

High-performance headlights that do not require driver action to be activated are categorized as “Standardequipped A”, while those that require driver action are categorized as “Standard-equipped B”. Based on this, wecan assume that in the event of an accident, Standard-equipped A high-performance headlights are more likely
to be in a high-beam state than Standard-equipped B high-performance headlights.
・ Compared to vehicles in which high-performance headlights are standard equipped (Standard-equipped A/B), a
lower proportion of vehicles in which high-performance headlights are not standard equipped (Non-standardequipped) have high-performance headlights. For this reason, in the event of an accident, the likelihood of suchvehicles using their high beams is even less than that of Standard-equipped B vehicles.
The indicator used here is based on the number of deaths per vehicle (1 million registered vehicles) for eachvehicle classification. When classifying vehicles by high-performance headlight equipping status, it is necessary tolook at the equipping status of each model. This was done by referring to the “List of Safety Equipment Equipping
Statuses (3)” published by NASVA (National Agency forNo. of vehicle
⾞種数
types

No. of registered
登録台数
vehiclesStandard標準装備A
equipped
A

25

4,856,860

2%Standard標準装備B
equipped
B
Nonstandard⾮標準装備
equipped

49

7,967,417

3%13376,364,763

33%

name was used for aggregation these totals. The number ofNot
equipped
装備無830 142,925,134

62%

registered vehicles, which was used as the denominator intotal

1037 232,114,174

100%

Automotive Safety & Victims' Aid) in addition to theowner’s manuals from each automobile manufacturer.
All available data from 2019 to 2022 for each model

Proportion割合these calculations, was first calculated by obtaining
information on the number of registered vehicles by model

Table 2. Numbers of registered vehicles per vehicle classification

name at the end of each year from 2018 to 2022 using a(4 years from 2019 to 2022)

formula such as that below.
Example: Number of registered vehicles in 2019 = (end of 2018 + end of 2019)/2Total number of registered vehicles for 4 years = 2019 + 2020 + 2021 + 2022 (number of registered vehicles ineach year)
Table 2 shows these calculation results.
3.

Results
Our results can be seen in Figure 5. Using four years data (2019 to 2022) from the Traffic Accident/Vehicle

Integrated Database, we calculated the number of accidents involving a four-wheeled vehicle and pedestrian inwhich the pedestrian died and in which the pedestrian was the primary or secondary party. The vertical bars in thefigure indicate a 95% reliability interval. As shown in the figure to the left, the number of deaths per one million
registered vehicles at nighttime is as follows:
Not equipped > Nonstandard-equipped > Standard-equipped A or Standard-equipped B

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ITARDA 26th Work Shop Report

As can be seen, there are significant differences between each. However, regarding whether driver action isnecessary for operation, there are no major differences between Standard-equipped A and Standard-equipped B, as
their reliability intervals overlap. Furthermore, no significant differences were seen between the different
classifications in the case of the daytime. Due to the above, Standard-equipped A and Standard-equipped B willboth be treated as “Standard-equipped” in this report.
10108866442

200
Non standard- 標準装備B
Standard- 標準装備A
StandardNot装備無equipped ⾮標準装備
equipped
equipped B
equipped A

Non standard- 標準装備B
StandardStandardNot装備無equipped ⾮標準装備
標準装備A
equipped
equipped B
equipped AFig. 5 Numbers of deaths per one million registered vehicles at nighttime (left figure) and in the daytime (right figure)

Next, in order to understand the reduction level of fatalequipped”,

120%“Nonstandard-equipped” and “Standard-equipped” were100%

divided by the value of “Not equipped” respectively, and80%

expressed as a proportion (see Fig. 6). In the case of

60%“nighttime”, “Standard-equipped” saw a reduction of 60%

40%

compared to “Not equipped”. However, in the case of20%“daytime”, the number of deaths reduced by about 30% for0%

accidents

whencomparedwith“Not“Standard-equipped”. If a reduction in accidents through theStandard標準装備
equipped

Nonstandard⾮標準装備
equipped↑With “Not equipped” at
100%
60%
reduction

74% 40%82% 68%Nighttime
夜Daytime昼

use of high beams is not evident in the case of daytime when

Fig. 6 Proportion of deaths due to vehicles not equipped withheadlights are not used, any reductions in fatalities during thehigh-performance headlights

daytime can be considered as being due to AEB (AutomaticEmergency Braking) activation in response to pedestrians.

120%

Because AEB responds to pedestrians even at night, any100%effects from AEB should also be included in the results for

80%

nighttime in Figure 6. Therefore, by dividing the proportionfor nighttime in Fig. 6 by the proportion for daytime, theeffects from AEB are offset, resulting in fatalities being
reduced by 40% for “Standard-equipped” when comparedwith “Not equipped” (see Fig. 7). This leads us to assume thatthe effectiveness of the AEB during the daytime and nighttime
is equal, and is regarded as the scenario in which thereductions in accidents due to high beam usage at night isestimated to be the lowest.

5↓With “Not equipped” inthe daytime at 100%40%
reduction

60%
40%
20%

90%

59%

Non
standard⾮標準装備
equipped

Standard標準装備

0%equipped

Fig. 7 Fatality proportions (nighttime/daytime/not equipped)ITARDA 26th Work Shop Report

4.

Summary

4-1. Findings
By aggregating data from 2019 to 2022 on accidents involving four-wheeled vehicles and pedestrians at nighttime
in which the pedestrian was killed, we were found that vehicles standard-equipped with high-performanceheadlights saw a 40% to 60% reduction in fatal accidents (per number of registered vehicles) compared to vehicles
not equipped with high-performance headlights. Because only 5% of registered vehicles are standard-equipped withhigh-performance headlights, we expect further reductions in the number of pedestrian fatalities at nighttime as theproportion of registered vehicles standard with high-performance headlights continues to increase.
4-2. Future issues for research
The results of this research are based on the assumption that high-performance headlights will function to someextent for models in which they are standard-equipped, meaning our conclusion is only an estimate. Becauseheadlights automatically distribute light upwards and downwards, data showing the direction of light distribution at
the time of an accident is necessary in order for more rigorous analysis to be conducted. In the case of the autodimming headlamps, not only is data on upwards/downwards light distribution necessary, but so is information onwhich areas are being illuminated. Because such data is recorded by EDRs (Event Data Recorders) and because
dashcams can also be used to record images of vehicle light distribution, we will be able to provide more accurate
analysis results as vehicles equipped with such equipment continue to increase. As someone who investigates,
analyzes, and disseminates the results of research on traffic accidents, I hope that the proliferation of such functions
will continue.

<References/Sources>(1) National Police Agency Website “Preventing Nighttime Accidents Involving Pedestrians by Skillfully Utilizing
High Beams”
https://www.npa.go.jp/bureau/traffic/anzen/highbeam.html(2) Ministry of Land, Infrastructure, Transport and Tourism (MLIT) “Survey Data on Technology ProliferationStatus” (see No. 30 and 31 in the table)
https://www.mlit.go.jp/jidosha/anzen/01asv/data/r3souchakudaisu.pdf(3) NASVA Website “List of Safety Equipment Equipping Statuses”
https://www.nasva.go.jp/mamoru/download/car_download.html(A link for latest edition of the “List of Safety Equipment Equipping Statuses” can be found in the middle ofthe page.)6