Road vehicles -- Prospective safety performance assessment of pre-crash technology by virtual simulation

This document describes the state-of-the-art of prospective methods for assessing the safety performance of vehicle-integrated active safety technologies by virtual simulation. The document describes how prospective assessment of vehicle-integrated technologies provides a prediction on how advanced vehicle safety technology will perform on the roads in real traffic. The focus is on the assessment of the technology as whole and not of single components of the technology (e.g. sensors). The described assessment approach is limited to “vehicle-integrated” technology and does not consider technologies operating off-board. The virtual simulation method per se is not limited to a certain vehicle type. The assessment approach discussed in this document focuses accident avoidance and the technology’s contribution to the mitigation of the consequences. Safety technologies that act in the in-crash or the post-crash phase are not explicitly addressed by the method, although the output from prospective assessments of crash avoidance technologies can be considered as an important input to determine the overall consequences of a crash. The method is intended as an overall reference for safety performance assessment studies of pre-crash technologies by virtual simulation. The method can be applied at all stages of technology development and in assessment after the market introduction, in which a wide range of stakeholders (manufactures, insurer, governmental organisation, consumer rating organisation) could apply the method.

Véhicules routiers -- Evaluation prospective de la performance sécuritaire des systèmes de pré-accident par simulation numérique

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Status
Published
Publication Date
22-Jun-2021
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
19-May-2021
Completion Date
19-May-2021
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TECHNICAL ISO/TR
REPORT 21934-1
First edition
2021-06
Road vehicles — Prospective safety
performance assessment of pre-crash
technology by virtual simulation —
Part 1:
State-of-the-art and general method
overview
Véhicules routiers — Evaluation prospective de la performance
sécuritaire des systèmes de pré-accident par simulation numérique —
Partie 1: Etat de l’art et aperçu des méthodes générales
Reference number
ISO/TR 21934-1:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO/TR 21934-1:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TR 21934-1:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols and abbreviated terms ........................................................................................................................................................... 3

4.1 Symbols ......................................................................................................................................................................................................... 3

4.2 Abbreviated terms ............................................................................................................................................................................... 3

5 Evaluation objective and baseline of assessment .............................................................................................................. 4

5.1 Definition of the evaluation objective ................................................................................................................................. 4

5.2 Establishment of baseline ............................................................................................................................................................. 6

6 Input data ..................................................................................................................................................................................................................... 7

6.1 General ........................................................................................................................................................................................................... 7

6.2 Active safety technology related data.................................................................................................................................. 8

6.3 Accident data ............................................................................................................................................................................................ 9

6.4 Data from naturalistic driving studies and field operation test.................................................................10

6.5 Infrastructure and traffic data ................................................................................................................................................11

6.6 Data from tests in controlled environments...............................................................................................................11

7 Implementation of virtual simulation ........................................................................................................................................11

7.1 General ........................................................................................................................................................................................................11

7.2 Simulation framework ...................................................................................................................................................................11

7.3 Simulation tool .....................................................................................................................................................................................12

7.4 Simulation models ............................................................................................................................................................................12

7.4.1 Vehicle model ...................................................................................................................................................................12

7.4.2 Safety technology model ........................................................................................................................................13

7.4.3 Environment model .................. ......................................................................................................................... .........14

7.4.4 Traffic situation model.............................................................................................................................................14

7.4.5 Traffic model ....................................................................................................................................................................15

7.4.6 Driver model .....................................................................................................................................................................16

7.4.7 Collision model ...............................................................................................................................................................16

7.5 Simulation control.............................................................................................................................................................................17

8 Estimating safety technology safety performance .........................................................................................................18

9 Validation and verification .....................................................................................................................................................................20

10 Practical experience ......................................................................................................................................................................................23

10.1 General ........................................................................................................................................................................................................23

10.2 Establishment of baseline ..........................................................................................................................................................23

10.3 Simulation framework ...................................................................................................................................................................24

10.4 Comparative study of different simulation tools ....................................................................................................24

10.5 Estimating the safety performance ....................................................................................................................................25

10.6 Validation and verification .........................................................................................................................................................25

11 Conclusions and limitations ..................................................................................................................................................................25

12 Outlook ........................................................................................................................................................................................................................27

12.1 General ........................................................................................................................................................................................................27

12.2 Automated driving ............................................................................................................................................................................27

12.3 V2X technologies ................................................................................................................................................................................28

Annex A (informative) List of tools ......................................................................................................................................................................30

Annex B (informative) Input and output of simulation models ............................................................................................31

Bibliography .............................................................................................................................................................................................................................36

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/TR 21934-1:2021(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 22 Road vehicles, Subcommittee SC 36

Safety and impact testing.
A list of all parts in the ISO 21934 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TR 21934-1:2021(E)
Introduction

Different Active Safety and Advanced Driver Assistance Systems (ADAS), in the following both referred

to as active safety technology, have been developed and introduced into the market. The question that

goes along with the development and introduction is, what impact these technologies have on road

traffic and more specifically, to what extent these technologies prevent crashes and injuries. Such

questions are of relevance for different stakeholders, such as vehicle manufacturers and suppliers, road

authorities, research organisations and academia, politics, insurance companies as well as consumer

[1]
organisations.

The answers to these questions are derived from assessment of such technologies in terms of road

traffic safety. Different assessment methodologies have been developed in the past and are being

[2]

used today. In general, the utilized methodologies can be divided in two types of assessment. The

first type determines the technology’s safety effect after its market introduction. Typically, in this

assessment type accident statistics are analysed in order to determine the difference between the

[1]

accident situation with the technology compared to a control group without the technology. These

methods are called retrospective assessment methods. A precondition for these methods is that the

technology under assessment has reached a sufficient penetration rate in the market and that sufficient

accident cases with and without the technology are recorded for a comparison. The penetration rate

does not necessarily need to be related to the whole vehicle fleet, but can also be related to a certain

[3]–[5]

vehicle subgroup or class. On the other hand, there are methods that predict the technology's

[6][7]

effect on traffic in relation to traffic safety before its market introduction. These methods are

called prospective methods using different approaches and tools.

This document focuses on the prospective assessment of traffic safety for vehicle-integrated

technologies acting in the pre-crash phase by means of virtual simulation.

The safety performance of a technology is determined by means of comparing data from the baseline

and treatment simulations based on a certain metric. The baseline for the assessment is the situation

without the vehicle-integrate technology under assessment present. The virtual simulation with the

technology is called treatment simulation.

The described assessment is limited to “vehicle-integrated” technology and does not consider

technologies operating off-board. The virtual simulation method per se is not limited to a certain vehicle

type. Although the main focus is often on passenger cars, the method is also applicable to motorised

two-wheelers as well as heavy goods vehicles. Furthermore, the assessment approach discussed in this

document focuses rather on accident avoidance and the technology’s contribution to the mitigation of

the consequences. Safety technologies that act in the in-crash or the post-crash phase are not explicitly

addressed by the method, although the output from prospective assessments of crash avoidance

technologies can be considered as an important input to determine the consequences. The extension

of the method to technologies, such as automated driving and V2X based technologies, are discussed in

the outlook at the end of this document.

In general, the assessment of active safety technologies requires the consideration of interaction with

surrounding traffic as well as the host vehicle driver. These interactions increase the complexity

of the assessment due to the high number of resulting variables. Consequently, for a comprehensive

assessment, the technology’s safety performance is analysed in a high number of test scenarios, in order

to cover all relevant circumstances that affect the critical situation and crashes. The virtual simulation

approach allows for running large numbers of test scenarios while offering a promising combination

of safety performance, flexibility, reproducibility, and experimental control. The need for using virtual

simulations in the prospective assessment of safety technologies is generally recognized. However,

standardized terminology and processes of methodological aspects to perform such assessments are

[1]

not available to date, which makes results hardly comparable. For this reason, automotive industry,

© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/TR 21934-1:2021(E)

research institutes, and academia joined in the P.E.A.R.S. (Prospective Effectiveness Assessment

for Road Safety) initiative with the objective to develop a comprehensible, reliable, transparent, and

accepted methodology for quantitative assessment of crash avoidance technology by virtual simulation.

[1]

This document aims to provide an overview on the state-of-the-art in the prospective assessment

of road safety for vehicle-integrated (active) safety technologies by means of virtual simulation, see

Figure 1.

After the introductive Clauses 1 to 4, the general method for a prospective assessment study is

described in Clause 5, where special attention is given to the definition of the traffic safety evaluation

scope and the establishment of the baseline. Clause 6 describes various data that can be used as input

for different tasks within the assessment procedure. Then a general virtual simulation framework and

various simulation models needed for conducting the simulation are presented in Clause 7, followed

by a description of the approaches to quantify the derived safety effect in Clause 8. A description of

validation and verification aspects as well as an overview on tools are given in Clause 9. Clause 10 of

the document provides a practical example of a comparative study of different simulation tools and

discusses the lessons learned. Clause 11 provides conclusions as well as describes limitations for the

state-of-the-art methods. Clause 12 provides an outlook towards the prospective safety performance

assessment for automated driving as well as the follow up to the current document.

Figure 1 — Overview of the process of prospective assessment of traffic safety for vehicle-

integrated safety technologies by means of virtual simulation and the structure of this

document

1) P.E.A.R.S. is an open consortium (established in 2012) in which engineers and researchers from the automotive

industry, research institutes and academia join with the objective to develop a comprehensible, reliable, transparent

and accepted methodology for quantitative assessment of crash avoidance technology by virtual simulation. Partners

of P.E.A.R.S. are (status Sep. 2020): Automotive Safety Technologies, AZT Automotive, BMW Group, Federal Highway

Research Institute (BASt), Chalmers University of Technology, Continental, Denso, Fraunhofer IVI, Generali, RWTH

Aachen University (ika), LAB, Swiss Re, TH Ingolstadt, Technical University Dresden, Technical University Graz, TNO,

Toyota, Technical University Dresden, TÜV Süd, University Leeds, UTAC CERAM, Virtual Vehicle, Volkswagen, Volvo

Cars, VUFO, ZF. More information at https:// pearsinitiative .com/ .
vi © ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
TECHNICAL REPORT ISO/TR 21934-1:2021(E)
Road vehicles — Prospective safety performance
assessment of pre-crash technology by virtual
simulation —
Part 1:
State-of-the-art and general method overview
1 Scope

This document describes the state-of-the-art of prospective methods for assessing the safety

performance of vehicle-integrated active safety technologies by virtual simulation. The document

describes how prospective assessment of vehicle-integrated technologies provides a prediction on

how advanced vehicle safety technology will perform on the roads in real traffic. The focus is on the

assessment of the technology as whole and not of single components of the technology (e.g. sensors).

The described assessment approach is limited to “vehicle-integrated” technology and does not consider

technologies operating off-board. The virtual simulation method per se is not limited to a certain

vehicle type. The assessment approach discussed in this document focuses accident avoidance and the

technology’s contribution to the mitigation of the consequences. Safety technologies that act in the in-

crash or the post-crash phase are not explicitly addressed by the method, although the output from

prospective assessments of crash avoidance technologies can be considered as an important input to

determine the overall consequences of a crash.

The method is intended as an overall reference for safety performance assessment studies of pre-crash

technologies by virtual simulation. The method can be applied at all stages of technology development

and in assessment after the market introduction, in which a wide range of stakeholders (manufactures,

insurer, governmental organisation, consumer rating organisation) could apply the method.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 12353-1, Road vehicles — Traffic accident analysis — Part 1: Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 12353-1 and the following

apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
levels of automation

levels that primarily identify how the “dynamic driving task” is divided between human and machine

Note 1 to entry: See Reference [8].
© ISO 2021 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO/TR 21934-1:2021(E)
3.2
baseline

initial set of data to which the performance of the technology under study is compared when performing

prospective assessments (3.7) of the technologies' performance
Note 1 to entry: This concept also complements treatment (3.13).
3.3
cooperative

applications based on vehicle-to-vehicle, vehicle-to-VRU and vehicle-to-infrastructure communication

3.4
host vehicle

vehicle, which is subject for assessment, i.e. is equipped with the technology in the treatment simulation

3.5
injury risk function
description of the probability of an injury in relation to crash attributes

Note 1 to entry: The most frequently used injury risk functions describe the probability of an injury occurrence

in relation to crash severity, e.g. impact speed or change of velocity.
3.6
projection

indicates what the future changes in a population would be if the assumptions (often based on patterns

of change which have previously occurred) about future trends actually occur

Note 1 to entry: Population projections – in the sense of Reference [9] - are estimates of total size or composition

of populations in the future, see Reference [10].
3.7
prospective assessment
assessment of the performance of technologies in a predictive way

Note 1 to entry: The assessment can be done, for example, before their deployment into a vehicle population.

3.8
target population
all situations or accidents that are addressed by the function under assessment
3.9
real-world data
data collected in a non-experimental, non-virtual situation
3.10
retrospective assessment

assessment of the performance of technologies after their deployment into a vehicle population

3.11
time series
series of data points indexed (or listed or graphed) in time order
3.12
traffic situation

crash-, near-crash or normal driving situation whose description can be considered for the

establishment of the baseline (3.2)
2 © ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/TR 21934-1:2021(E)
3.13
treatment

use of a specific technology to affect the course of an event in a traffic situation (3.12) in order to avoid

or mitigate crashes

Note 1 to entry: Treatment simulations provide data on the performance of the technology under assessment

to compare with the baseline (3.2) data when performing prospective assessments (3.7) of performance of

technologies.
Note 2 to entry: This concept also complements baseline (3.2).
3.14
test scenario

detailed description of trajectories, geometrical relations, speeds, etc. of a traffic situation (3.12)

Note 1 to entry: See References [11]–[13].
3.15
vehicle-integrated
technology under assessment operating on-board of the vehicle
4 Symbols and abbreviated terms
4.1 Symbols
E Effectiveness / safety performance

Weighted frequency of the metric (e.g. percentage of crashes) in the simulation without

the technology under assessment

Weighted frequency of the metric (e.g. percentage of crashes) in the simulation with the

technology under assessment
v Velocity
4.2 Abbreviated terms
ACC Adaptive Cruise Control
ADAS Advance Driver Assistance Systems
AEB Autonomous Emergency Braking
BAAC Analysis report of road accidents involving physical injury (France)
BASt Federal Highway Research Institute (Bundesanstalt für Straßenwesen)
CEDATU Central Database for In-Depth Accident Studies (Austria)
CIDAS China In-Depth Accident Study
EES Energy Equivalent Speed
ETAC European Truck Accident Causation
FESTA Field opErational teSts supporT Action
FOT Field Operation Test
© ISO 2021 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO/TR 21934-1:2021(E)
GIDAS German In-Depth Accident Study
HIL Hardware-in-the-loop
IEC International Electrotechnical Commission
IIHS Insurance Institute for Highway Safety
IGLAD Initiative of Global Harmonisation of Accident Databases
ISO International Organization for Standardization
ITARDA Institute for Traffic Accent Research and Data Analysis
J-TAD Japan Traffic Accidents Databases
KBA German Federal Motor Transport Authority (Kraftfahrtbundesamt)
LDW Lane Departure Warning System
LIDAR Light detection and ranging
MIL Model-in-the-loop
NASS National Automotive Sampling System
NDS Naturalistic Driving Studies
RAIDS Road Accident In Depth Studies
P.E.A.R.S. Prospective Effectiveness Assessment for Road Safety
PTW Powered Two Wheelers
RASSI Road Accident Sampling System - India

SCP (cr/cl) Straight Crossing Paths (cyclist from the right / cyclist from the left)

SIL Software–in-the-loop
TTC Time to collision
V2X Vehicle to X (Vehicle and / or Infrastructure) Communication
VIN Vehicle identification number
VRU Vulnerable Road User
V&V Validation and Verification
5 Evaluation objective and baseline of assessment
5.1 Definition of the evaluation objective

Since there are numerous objectives to conduct prospective safety performance assessments, it

is important that a precise research question for the assessment is formulated. Then by identifying

relevant traffic situations – the target population - to address the research question, a more precise

[14]

specification and application for a virtual simulation study is provided. Figure 2 shows the place in

the process overview.
4 © ISO 2021 – All rights reserved
---------------------- Page: 10 ----------------------
ISO/TR 21934-1:2021(E)
Figure 2 — Overview of the process — Definition of the evaluation objective
[1]

Various objectives to conduct safety performance assessments have been identified, the main ones

are:

— quantification of effects (positive and negative) of a certain technology in terms of traffic safety;

— prioritization and optimization of safety technologies during research and development;

— identification of business opportunities and anticipation of regulations and consumer testing.

Furthermore, two types of processes are used to formulate the target for this kind of studies.

— A technology-driven process in which a request is put forward to estimate the safety benefit of a

safety technology. This technology can be more or less defined at the time of the study; it can be an

idea, a concept, a product under development or a product that already has been implemented but

not introduced into the market (also often called a bottom-up approach).

— A traffic safety-driven process in which existing or expected safety problems or certain relevant

traffic situations are identified. In this case, the target for the study is not linked to a particular

safety technology but to a targeted lack of safety (also often called top-down approach).

Hence, it is important to note that if results between different studies are compared the res

...

TECHNICAL ISO/TR
REPORT 21934-1
First edition
Road vehicles — Prospective safety
performance assessment of pre-crash
technology by virtual simulation —
Part 1:
State-of-the-art and general method
overview
Véhicules routiers — Evaluation prospective de la performance
sécuritaire des systèmes de pré-accident par simulation numérique —
Partie 1: Etat de l’art et aperçu des méthodes générales
PROOF/ÉPREUVE
Reference number
ISO/TR 21934-1:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO/TR 21934-1:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TR 21934-1:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols and abbreviated terms ........................................................................................................................................................... 3

4.1 Symbols ......................................................................................................................................................................................................... 3

4.2 Abbreviations ........................................................................................................................................................................................... 3

5 Evaluation objective and baseline of assessment .............................................................................................................. 4

5.1 Definition of the evaluation objective ................................................................................................................................. 4

5.2 Establishment of baseline ............................................................................................................................................................. 6

6 Input data ..................................................................................................................................................................................................................... 7

6.1 General ........................................................................................................................................................................................................... 7

6.2 Active safety technology related data.................................................................................................................................. 8

6.3 Accident data ............................................................................................................................................................................................ 9

6.4 Data from naturalistic driving studies and field operation test.................................................................10

6.5 Infrastructure and traffic data ................................................................................................................................................11

6.6 Data from tests in controlled environments...............................................................................................................11

7 Implementation of virtual simulation ........................................................................................................................................11

7.1 General ........................................................................................................................................................................................................11

7.2 Simulation framework ...................................................................................................................................................................11

7.3 Simulation tool .....................................................................................................................................................................................12

7.4 Simulation models ............................................................................................................................................................................12

7.4.1 Vehicle model ...................................................................................................................................................................12

7.4.2 Safety technology model ........................................................................................................................................13

7.4.3 Environment model .................. ......................................................................................................................... .........14

7.4.4 Traffic situation model.............................................................................................................................................14

7.4.5 Traffic model ....................................................................................................................................................................15

7.4.6 Driver model .....................................................................................................................................................................16

7.4.7 Collision model ...............................................................................................................................................................16

7.5 Simulation control.............................................................................................................................................................................17

8 Estimating safety technology safety performance .........................................................................................................18

9 Validation and verification .....................................................................................................................................................................20

10 Practical experience ......................................................................................................................................................................................23

10.1 General ........................................................................................................................................................................................................23

10.2 Establishment of baseline ..........................................................................................................................................................23

10.3 Simulation framework ...................................................................................................................................................................23

10.4 Comparative study of different simulation tools ....................................................................................................24

10.5 Estimating the safety performance ....................................................................................................................................24

10.6 Validation and verification .........................................................................................................................................................24

11 Conclusions and limitations ..................................................................................................................................................................25

12 Outlook ........................................................................................................................................................................................................................26

12.1 General ........................................................................................................................................................................................................26

12.2 Automated driving ............................................................................................................................................................................27

12.3 V2X technologies ................................................................................................................................................................................28

Annex A (informative) List of tools ......................................................................................................................................................................29

Annex B (informative) Input and output of simulation models ............................................................................................30

Bibliography .............................................................................................................................................................................................................................35

© ISO 2021 – All rights reserved PROOF/ÉPREUVE iii
---------------------- Page: 3 ----------------------
ISO/TR 21934-1:2021(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 22 Road vehicles, Subcommittee SC 36

Safety and impact testing.
A list of all parts in the ISO 21934 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TR 21934-1:2021(E)
Introduction

Different Active Safety and Advanced Driver Assistance Systems (ADAS), in the following both referred

to as active safety technology, have been developed and introduced into the market. The question that

goes along with the development and introduction is, what impact these technologies have on road

traffic and more specifically, to what extent these technologies prevent crashes and injuries. Such

questions are of relevance for different stakeholders, such as vehicle manufacturers and suppliers, road

authorities, research organisations and academia, politics, insurance companies as well as consumer

[1]
organisations.

The answers to these questions are derived from assessment of such technologies in terms of road

traffic safety. Different assessment methodologies have been developed in the past and are being

[2]

used today. In general, the utilized methodologies can be divided in two types of assessment. The

first type determines the technology’s safety effect after its market introduction. Typically, in this

assessment type accident statistics are analysed in order to determine the difference between the

[1]

accident situation with the technology compared to a control group without the technology. These

methods are called retrospective assessment methods. A precondition for these methods is that the

technology under assessment has reached a sufficient penetration rate in the market and that sufficient

accident cases with and without the technology are recorded for a comparison. The penetration rate

does not necessarily need to be related to the whole vehicle fleet, but can also be related to a certain

[3]–[5]

vehicle subgroup or class. On the other hand, there are methods that predict the technology's

[6][7]

effect on traffic in relation to traffic safety before its market introduction. These methods are

called prospective methods using different approaches and tools.

This document focuses on the prospective assessment of traffic safety for vehicle-integrated

technologies acting in the pre-crash phase by means of virtual simulation.

The safety performance of a technology is determined by means of comparing data from the baseline

and treatment simulations based on a certain metric. The baseline for the assessment is the situation

without the vehicle-integrate technology under assessment present. The virtual simulation with the

technology is called treatment simulation.

The described assessment is limited to “vehicle-integrated” technology and does not consider

technologies operating off-board. The virtual simulation method per se is not limited to a certain vehicle

type. Although the main focus is often on passenger cars, the method is also applicable to motorised

two-wheelers as well as heavy goods vehicles. Furthermore, the assessment approach discussed in this

document focuses rather on accident avoidance and the technology’s contribution to the mitigation of

the consequences. Safety technologies that act in the in-crash or the post-crash phase are not explicitly

addressed by the method, although the output from prospective assessments of crash avoidance

technologies can be considered as an important input to determine the consequences. The extension

of the method to technologies, such as automated driving and V2X based technologies, are discussed in

the outlook at the end of this document.

In general, the assessment of active safety technologies requires the consideration of interaction with

surrounding traffic as well as the host vehicle driver. These interactions increase the complexity

of the assessment due to the high number of resulting variables. Consequently, for a comprehensive

assessment, the technology’s safety performance is analysed in a high number of test scenarios, in order

to cover all relevant circumstances that affect the critical situation and crashes. The virtual simulation

approach allows for running large numbers of test scenarios while offering a promising combination

of safety performance, flexibility, reproducibility, and experimental control. The need for using virtual

simulations in the prospective assessment of safety technologies is generally recognized. However,

standardized terminology and processes of methodological aspects to perform such assessments are

[1]

not available to date, which makes results hardly comparable. For this reason, automotive industry,

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research institutes, and academia joined in the P.E.A.R.S. (Prospective Effectiveness Assessment

for Road Safety) initiative with the objective to develop a comprehensible, reliable, transparent, and

accepted methodology for quantitative assessment of crash avoidance technology by virtual simulation.

[1]

This document aims to provide an overview on the state-of-the-art in the prospective assessment

of road safety for vehicle-integrated (active) safety technologies by means of virtual simulation, see

Figure 1.

After the introductive Clauses 1 to 4, the general method for a prospective assessment study is

described in Clause 5, where special attention is given to the definition of the traffic safety evaluation

scope and the establishment of the baseline. Clause 6 describes various data that can be used as input

for different tasks within the assessment procedure. Then a general virtual simulation framework and

various simulation models needed for conducting the simulation are presented in Clause 7, followed

by a description of the approaches to quantify the derived safety effect in Clause 8. A description of

validation and verification aspects as well as an overview on tools are given in Clause 9. Clause 10 of

the document provides a practical example of a comparative study of different simulation tools and

discusses the lessons learned. Clause 11 provides conclusions as well as describes limitations for the

state-of-the-art methods. Clause 12 provides an outlook towards the prospective safety performance

assessment for automated driving as well as the follow up to the current document.

Figure 1 — Overview of the process of prospective assessment of traffic safety for vehicle-

integrated safety technologies by means of virtual simulation and the structure of this

document

1) P.E.A.R.S. is an open consortium (established in 2012) in which engineers and researchers from the automotive

industry, research institutes and academia join with the objective to develop a comprehensible, reliable, transparent

and accepted methodology for quantitative assessment of crash avoidance technology by virtual simulation. Partners

of P.E.A.R.S. are (status Sep. 2020): Automotive Safety Technologies, AZT Automotive, BMW Group, Federal Highway

Research Institute (BASt), Chalmers University of Technology, Continental, Denso, Fraunhofer IVI, Generali, RWTH

Aachen University (ika), LAB, Swiss Re, TH Ingolstadt, Technical University Dresden, Technical University Graz, TNO,

Toyota, Technical University Dresden, TÜV Süd, University Leeds, UTAC CERAM, Virtual Vehicle, Volkswagen, Volvo

Cars, VUFO, ZF. More information at https:// pearsinitiative .com/ .
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TECHNICAL REPORT ISO/TR 21934-1:2021(E)
Road vehicles — Prospective safety performance
assessment of pre-crash technology by virtual
simulation —
Part 1:
State-of-the-art and general method overview
1 Scope

This document describes the state-of-the-art of prospective methods for assessing the safety

performance of vehicle-integrated active safety technologies by virtual simulation. The document

describes how prospective assessment of vehicle-integrated technologies provides a prediction on

how advanced vehicle safety technology will perform on the roads in real traffic. The focus is on the

assessment of the technology as whole and not of single components of the technology (e.g. sensors).

The described assessment approach is limited to “vehicle-integrated” technology and does not consider

technologies operating off-board. The virtual simulation method per se is not limited to a certain

vehicle type. The assessment approach discussed in this document focuses accident avoidance and the

technology’s contribution to the mitigation of the consequences. Safety technologies that act in the in-

crash or the post-crash phase are not explicitly addressed by the method, although the output from

prospective assessments of crash avoidance technologies can be considered as an important input to

determine the overall consequences of a crash.

The method is intended as an overall reference for safety performance assessment studies of pre-crash

technologies by virtual simulation. The method can be applied at all stages of technology development

and in assessment after the market introduction, in which a wide range of stakeholders (manufactures,

insurer, governmental organisation, consumer rating organisation) could apply the method.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 12353-1, Road vehicles — Traffic accident analysis — Part 1: Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 12353-1 and the following

apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
levels of automation

levels that primarily identify how the “dynamic driving task” is divided between human and machine

Note 1 to entry: See Reference [8].
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ISO/TR 21934-1:2021(E)
3.2
baseline

initial set of data to which the performance of the technology under study is compared when performing

prospective assessments (3.7) of the technologies' performance
Note 1 to entry: This concept also complements treatment (3.13).
3.3
cooperative

applications based on vehicle-to-vehicle, vehicle-to-VRU and vehicle-to-infrastructure communication

3.4
host vehicle

vehicle, which is subject for assessment, i.e. is equipped with the technology in the treatment simulation

3.5
injury risk function
description of the probability of an injury in relation to crash attributes

Note 1 to entry: The most frequently used injury risk functions describe the probability of an injury occurrence

in relation to crash severity, e.g. impact speed or change of velocity.
3.6
projection

indicates what the future changes in a population would be if the assumptions (often based on patterns

of change which have previously occurred) about future trends actually occur

Note 1 to entry: Population projections – in the sense of Reference [9] - are estimates of total size or composition

of populations in the future, see Reference [10].
3.7
prospective assessment
assessment of the performance of technologies in a predictive way

Note 1 to entry: The assessment can be done, for example, before their deployment into a vehicle population.

3.8
target population
all situations or accidents that are addressed by the function under assessment
3.9
real-world data
real-world traffic situations
data collected in a non-experimental, non-virtual situation
3.10
retrospective assessment

assessment of the performance of technologies after their deployment into a vehicle population

3.11
time series
series of data points indexed (or listed or graphed) in time order
3.12
traffic situation

crash-, near-crash or normal driving situation whose description can be considered for the

establishment of the baseline (3.2)
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ISO/TR 21934-1:2021(E)
3.13
treatment

use of a specific technology to affect the course of an event in a traffic situation (3.12) in order to avoid

or mitigate crashes

Note 1 to entry: Treatment simulations provide data on the performance of the technology under assessment

to compare with the baseline (3.2) data when performing prospective assessments (3.7) of performance of

technologies.
Note 2 to entry: This concept also complements baseline (3.2).
3.14
test scenario

detailed description of trajectories, geometrical relations, speeds, etc. of a traffic situation (3.12)

Note 1 to entry: See References [11]–[13].
3.15
vehicle-integrated
technology under assessment operating on-board of the vehicle
4 Symbols and abbreviated terms
4.1 Symbols
E Effectiveness / safety performance

Weighted frequency of the metric (e.g. percentage of crashes) in the simulation without

the technology under assessment

Weighted frequency of the metric (e.g. percentage of crashes) in the simulation with the

technology under assessment
v Velocity
4.2 Abbreviations
ACC Adaptive Cruise Control
ADAS Advance Driver Assistance Systems
AEB Autonomous Emergency Braking
BAAC Analysis report of road accidents involving physical injury (France)
BASt Federal Highway Research Institute (Bundesanstalt für Straßenwesen)
CEDATU Central Database for In-Depth Accident Studies (Austria)
CIDAS China In-Depth Accident Study
EES Energy Equivalent Speed
ETAC European Truck Accident Causation
FESTA Field opErational teSts supporT Action
FOT Field Operation Test
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ISO/TR 21934-1:2021(E)
GIDAS German In-Depth Accident Study
HIL Hardware-in-the-loop
IEC International Electrotechnical Commission
IIHS Insurance Institute for Highway Safety
IGLAD Initiative of Global Harmonisation of Accident Databases
ISO International Organization for Standardization
ITARDA Institute for Traffic Accent Research and Data Analysis
J-TAD Japan Traffic Accidents Databases
KBA German Federal Motor Transport Authority (Kraftfahrtbundesamt)
LDW Lane Departure Warning System
LIDAR Light detection and ranging
MIL Model-in-the-loop
NASS National Automotive Sampling System
NDS Naturalistic Driving Studies
RAIDS Road Accident In Depth Studies
P.E.A.R.S. Prospective Effectiveness Assessment for Road Safety
PTW Powered Two Wheelers
RASSI Road Accident Sampling System - India

SCP (cr/cl) Straight Crossing Paths (cyclist from the right / cyclist from the left)

SIL Software–in-the-loop
TTC Time to collision
V2X Vehicle to X (Vehicle and / or Infrastructure) Communication
VIN Vehicle identification number
VRU Vulnerable Road User
V&V Validation and Verification
5 Evaluation objective and baseline of assessment
5.1 Definition of the evaluation objective

Since there are numerous objectives to conduct prospective safety performance assessments, it

is important that a precise research question for the assessment is formulated. Then by identifying

relevant traffic situations – the target population - to address the research question, a more precise

[14]

specification and application for a virtual simulation study is provided. Figure 2 shows the place in

the process overview.
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ISO/TR 21934-1:2021(E)
Figure 2 — Overview of the process — Definition of the evaluation objective
[1]

Various objectives to conduct safety performance assessments have been identified, the main ones

are:

— quantification of effects (positive and negative) of a certain technology in terms of traffic safety;

— prioritization and optimization of safety technologies during research and development;

— identification of business opportunities and anticipation of regulations and consumer testing.

Furthermore, two types of processes are used to formulate the target for this kind of studies.

— A technology-driven process in which a request is put forward to estimate the safety benefit of a

safety technology. This technology can be more or less defined at the time of the study; it can be an

idea, a concept, a product under development or a product that already has been implemented but

not introduced into the market (also often called a bottom-up approach).

— A traffic safety-driven process in which existing or expected safety problems or certain relevant

traffic situations are identified. In this case, the target for the study is not linked to a particular

safety technology but to a
...

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