ISO/TS 20459:2023

Road vehicles — Injury risk functions for advanced pedestrian legform impactor (aPLI)

This document provides definitions, symbols and injury probability functions (IPFs) for the thigh, leg and knee intended to be used with the advanced pedestrian legform impactor (aPLI), a standardized pedestrian legform impactor with an upper mass for pedestrian subsystem testing of road vehicles. They are applicable to impact tests using the aPLI at 11,1 m/s involving: — vehicles of category M1, except vehicles with a maximum mass above 2 500 kg and which are derived from N1 category vehicles and where the driver’s position, the R-point, is either forward of the front axle or longitudinally rearwards of the front axle transverse centreline by a maximum of 1 100 mm; — vehicles of category N1, except where the driver’s position, the R-point, is either forward of the front axle or longitudinally rearwards of the front axle transverse centreline by maximum of 1 100 mm; — impacts to the bumper test area defined by References [1] and [2]; — pedestrian subsystem tests involving use of a legform for the purpose of evaluating compliance with vehicle safety standards.

Véhicules routiers — Critères lésionnels et courbes de risques pour l'impacteur en forme de jambe de piéton (aPLI).

General Information

• Status: Published
• Publication Date: 27-Apr-2023
• ICS: 43.020 - Road vehicles in general
• Technical Committee: ISO/TC 22/SC 36 - Safety and impact testing
• Drafting Committee: ISO/TC 22/SC 36/WG 6 - Performance criteria expressed in biomechanical terms
• Current Stage: 6060 - International Standard published
• Start Date: 28-Apr-2023
• Due Date: 27-Jan-2023
• Completion Date: 28-Apr-2023

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 20459
First edition
2023-04
Road vehicles — Injury risk functions
for advanced pedestrian legform
impactor (aPLI)
Véhicules routiers — Critères lésionnels et courbes de risques pour
l'impacteur en forme de jambe de piéton (aPLI).
Reference number
ISO/TS 20459:2023(E)
© ISO 2023

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ISO/TS 20459:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Website: www.iso.org
Published in Switzerland
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ISO/TS 20459:2023(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 . 4
5 IPFs for the aPLI . 4
5.1 General . 4
5.2 Thigh . . 6
5.3 Leg. 7
5.4 Knee . . 8
Annex A (informative) Rationale regarding background and methodology to develop IPFs
for the aPLI .11
Annex B (informative) Adjustment of IPFs for real-world relevance . 105
Annex C (informative) Supplemental data . 135
Annex D (informative) Influence of PMHS test data (dfbetas > 0,3) against IPFs for human . 136
Bibliography .154
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ISO/TS 20459:2023(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.
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.
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ISO/TS 20459:2023(E)
Introduction
This document has been prepared on the basis of the existing injury probability functions (IPFs) to be
used with the advanced pedestrian legform impactor (aPLI) standard build level B (SBL-B). The purpose
of this document is to document the IPFs for the aPLI in a form suitable and intended for worldwide
harmonized use.
In 2014, development of the aPLI hardware and associated IPFs started, with the aim of defining
a globally accepted next-generation pedestrian legform impactor with enhanced biofidelity and
injury assessment capability, along with its IPFs, suitable for harmonized use. Participating in the
development were research institutes, dummy and instrumentation manufacturers, governments, and
car manufacturers from around the world.
IPFs for the aPLI specified in this document predict injury probability to specific regions of the lower
limb of a pedestrian that corresponds to maximum values of injury metrics obtained by the aPLI in a
subsystem test, as described in References [1] and [2]. As the IPFs do not provide any threshold values,
users will need to determine target injury probability, based on their specific needs, to define injury
assessment reference values to be used for their test protocol.
It is also important to note that the subsystem test procedure (STP) for pedestrian protection may not
be representative of pedestrian accidents for specific injury metrics, depending on their sensitivity to
pedestrian impact conditions such as lower-limb posture and muscle tone. The IPFs for the aPLI have
been validated against accident data and some ideas to compensate for the discrepancy against accident
data are presented in Annex B.
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TECHNICAL SPECIFICATION ISO/TS 20459:2023(E)
Road vehicles — Injury risk functions for advanced
pedestrian legform impactor (aPLI)
1 Scope
This document provides definitions, symbols and injury probability functions (IPFs) for the thigh, leg
and knee intended to be used with the advanced pedestrian legform impactor (aPLI), a standardized
pedestrian legform impactor with an upper mass for pedestrian subsystem testing of road vehicles.
They are applicable to impact tests using the aPLI at 11,1 m/s involving:
— vehicles of category M1, except vehicles with a maximum mass above 2 500 kg and which are derived
from N1 category vehicles and where the driver’s position, the R-point, is either forward of the front
axle or longitudinally rearwards of the front axle transverse centreline by a maximum of 1 100 mm;
— vehicles of category N1, except where the driver’s position, the R-point, is either forward of the front
axle or longitudinally rearwards of the front axle transverse centreline by maximum of 1 100 mm;
— impacts to the bumper test area defined by References [1] and [2];
— pedestrian subsystem tests involving use of a legform for the purpose of evaluating compliance
with vehicle safety standards.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology 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
adult
person who is sixteen years old or older
3.2
advanced pedestrian legform impactor
aPLI
modified pedestrian legform impactor which incorporates a mass representing the inertial effect of
the upper part of a pedestrian body to enhance biofidelity and injury assessment capability (3.10) of
conventional pedestrian legforms
3.3
biofidelity
aspect of the advanced pedestrian legform impactor (aPLI) (3.2) capability to represent the impact
response of human subjects
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ISO/TS 20459:2023(E)
3.4
BLE height
bonnet leading edge height
height of the geometric trace of the upper most points of contact between a straight edge and the front-
end of the car
3.5
bumper test area
test area of the legform to bumper impact test
3.6
bumper system
component installed at the hip joint inside the upper mass composed of the bumper, the bumper mount
and the compression surface, designed to apply a force on the upper part of the femur in adduction to
enhance injury assessment capability (3.10) of the advanced pedestrian legform impactor (aPLI) (3.2)
3.7
EE method
energy-equivalent method
method of developing injury probability functions (IPFs) (3.11) for the advanced pedestrian legform
impactor (aPLI) (3.2) by transferring human injury values to those of an aPLI using the absorbed energy
3.8
high-bumper car
car with a lower bumper reference line height (3.14) of 425 mm or more
3.9
hip joint
uniaxial joint that allows abduction and adduction and connects the upper mass with the lower limb
3.10
injury assessment capability
aspect of the advanced pedestrian legform impactor (aPLI) (3.2) capability to produce peak injury values
that correlate with those obtained from human body model impact simulations
3.11
IPF
injury probability function
function which defines the relationship between a peak value of an injury metric and probability of
injury for a specific load case
3.12
ISO metric
objective rating metric used in this document to verify time histories of sensor output against
experimentally or computationally produced target time histories as detailed in ISO/TS 18571:2014
3.13
low-bumper car
car with a lower bumper reference line height (3.14) less than 425 mm
3.14
LBRL height
lower bumper reference line height
height of the geometric trace of the lowermost points of contact between a straight edge and the
bumper, measured from the ground
3.15
low-pass filter
filter which permits only low-frequency (100 Hz or less) oscillations
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ISO/TS 20459:2023(E)
3.16
paired test method
method of developing injury probability functions (IPFs) (3.11) by correlating human injury occurrence
in a specific impact configuration with the injury value measured by an ATD subjected to the same
impact as detailed in ISO/TR 12350:2013
3.17
subsystem test
test to evaluate safety performance of cars where subsystem impactors representing individual
body regions of a pedestrian are propelled into a front end of a stationary car, in impact conditions
representing specific load cases in car-pedestrian accidents
3.18
transfer function
TF
linear regression function between human injury values predicted by human body models and advanced
pedestrian legform impactor (aPLI) (3.2) injury values
3.19
TF method
transfer-function method
method of developing injury probability functions (IPFs) (3.11) for the advanced pedestrian legform
impactor (aPLI) (3.2) by converting human IPFs to those of the aPLI using corresponding transfer
functions (3.18)
4 Symbols and abbreviated terms
4.1 Symbols
See Table 1.
Table 1 — Symbols and their meanings
Symbol Meaning
C Parameter determined for the Weibull distribution for human IPFs
Scale
C
Parameter determined for the Weibull distribution for human IPFs
Shape
C
Slope of the transfer function
Slope
C
Parameter determined for the Log-Normal distribution for human IPFs
μ
C Parameter determined for the Log-Normal distribution for human IPFs
σ
C Correction factor determined to adjust to the real-world accident data
TA1
C Correction factor determined to adjust to the real-world accident data
TA2
F IPF for human
G Transfer function
I Injury metric for human
human
I Injury metric for the aPLI
aPLI
P Injury probability of human
P
Adjusted injury probability for the MCL
adj
x Value of the injury metric for the aPLI
aPLI
x Value of the injury metric for human
human
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ISO/TS 20459:2023(E)
4.2 Abbreviated terms
See Table 2.
Table 2 — Abbreviated terms and their meanings
Abbreviation Meaning
ACL Anterior Cruciate Ligament
aPLI advanced Pedestrian Legform Impactor
ATD Anthropometric Test Device
BLE Bonnet Leading Edge
BM Bending Moment
BP Bumper
EE Energy Equivalent
EEVC European Enhanced Vehicle-safety Committee
FE Finite Element
HBM Human Body Model
IPF Injury Probability Function
LBRL Lower Bumper Reference Line
MCL Medial Collateral Ligament
PCL Posterior Cruciate Ligament
PMHS Post Mortem Human Subjects
RCM Real Car Model
SCM Simplified Car Model
SP Spoiler
STP Subsystem Test Procedure
TF Transfer Function
TG Task Group
5 IPFs for the aPLI
5.1 General
The IPFs specified in this document are to be used with the aPLI for the thigh, leg and knee to predict
the probability of injuries to pedestrians when involved in real-world car-pedestrian accidents. The
IPFs provide a statistically derived relationship between the maximum values of injury metrics
obtained from a test conducted using the aPLI by following the subsystem test procedure (STP), and
the probability of injury to a corresponding body region of a pedestrian when subjected to load cases
representative of the majority of real-world accidents.
The specific load case represented by the subsystem legform test is described below:
th
— pedestrian size and weight: 175,1 cm and 76,7 kg representing a 50 percentile adult male (Reference
[3]);
— impact speed: 11,1 m/s;
— impact direction: lateral-to-medial direction to a pedestrian lower limb;
— lower-limb posture: upright (vertical to the ground) with the knee fully extended;
— impact height: sole of the foot positioned 25 mm above the ground to represent a shoe sole height.
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ISO/TS 20459:2023(E)
First, human IPFs were determined using human biomechanical data available from the literature. Data
obtained by the experiments conducted under the loading conditions equivalent to those specified in
the STP were referred to. The statistical method used to derive human IPFs follows that recommended
by ISO/TS 18506 with the covariates of pedestrian size, weight and age. The pedestrian size and weight
were determined from those specified in STP. The age was set at 60 years old that corresponds to the
average age of the subjects of the biomechanical data as this choice was found to provide the most
reasonable set of assumptions when the IPFs were fitted to the accident data. The recommended
method estimates parameters of any one of the Weibull, Log-Normal or Log-Logistic distribution
(choose the one that best fits to data) with survival analysis method. In this document, one of the three
distributions (Weibull distribution, Log-Normal distribution or Log-Logistic distribution) is used to
define human IPFs for each of the injury metrics. The formulae of the aPLI IPFs for these distributions
are presented below.
The injury probability when the Weibull distribution is applied following Formula (1):
C
 Shape 
Cx×
 
 SlopeaPLI 
P =−1exp − (1)
   
C
  Scale  
 
where
P is the injury probability of human;
C
is the parameter determined for the Weibull distribution for human IPFs;
Scale
C
is the parameter determined for the Weibull distribution for human IPFs;
Shape
C
is the slope of the transfer function (TF);
Slope
x
is the value of the injury metric for the aPLI.
aPLI
The injury probability when the Log-Normal distribution is applied following Formula (2):
2
 
Cx× −− ln −tC−
()
1 1
SlopeaPLI  μμ 
P = exp dt (2)
 
∫
2
0
t
C 2ππ
2C
 
σσ
σσ
 
where
P is the injury probability of human;
C
is the parameter determined for the Log-Normal distribution for human IPFs;
μ
C
is the parameter determined for the Log-Normal distribution for human IPFs;
σ
C
is the slope of the TF;
Slope
x
is the value of the injury metric for the aPLI.
aPLI
The injury probability when the Log-Logistic distribution is applied following Formula (3):
1
P = (3)
−−1
C ×x
 C
SlopeaPLI
Shape
1++
 
exp C
()
 Scale 
where
P is the injury probability of human;
C
is the parameter determined for the Log-Logistic distribution for human IPFs;
Scale
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ISO/TS 20459:2023(E)
C
is the parameter determined for the Log-Logistic distribution for human IPFs;
Shape
C
is the slope of the TF;
Slope
x
is the value of the injury metric for the aPLI.
aPLI
For each of the thigh, leg and knee, IPFs for a human body are then transferred to those of the aPLI using
a TF, which is a linear function between the maximum values of a human and aPLI injury metrics. Due
to the lack of biomechanical data, the TFs were determined from the results of computational impact
simulations using FE human body models (HBMs) and aPLI FE models in loading conditions specified
in the STP. Details of the human IPFs from which IPFs for the aPLI are derived can be found in A.2.3. For
the determination of TFs, see A.2.4 for more details.
As the IPFs converted from human IPFs using TFs are for the specific load case defined in the STP, the
number of injuries calculated from each of the injury probabilities predicted by the IPFs were compared
with that of real-world accidents. The IPFs for the knee and the leg were compensated for the real-world
observations for the injury metrics showing a significant inconsistency with accident data. Details of
the compensation to real-world accidents can be found in Annex B.
Supplemental information related to the TFs and IPFs for human is provided in Annex C and Annex D,
respectively.
5.2 Thigh
The IPF for the thigh defines probability of femur shaft fracture to a pedestrian subjected to the load
cases representative of the majority of real-world accidents as a function of maximum value of the
femur bending moment measured by the aPLI.
Figure 1 presents the IPF for the thigh. The injury probability function is shown in a solid line, with the
95 % confidence interval shown in dotted lines. The horizontal axis represents the maximum value of
the femur bending moment measured by the aPLI, and the vertical axis represents the probability of
injury.
The IPF for the thigh is given by Formula (4):
C
Shape
 
Cx×
 
 SlopeaPLI 
P =−1exp − (4)
   
C
 Scale 
 
 
where
P is the injury probability for the femur shaft of human;
C
is the parameter determined for the Weibull distribution for the human IPF for the femur
Scale
shaft as described in A.2.3.4.1;
C
is the parameter determined for the Weibull distribution for the human IPF for the femur
Shape
shaft as described in A.2.3.4.1;
C
is the slope of the TF for the thigh as described in A.2.4.4.1;
Slope
x
is the femur BM measured by the aPLI in Nm.
aPLI
The parameters needed to define the IPF ( C , C and C ) for the function are described in
Scale Shape Slope
Table 3.
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ISO/TS 20459:2023(E)
Key
X aPLI femur BM [Nm]
Y probability of femur shaft fracture
aPLI IPF for femur shaft
95 % confidence interval
observed data
Figure 1 — IPF for the femur shaft
Table 3 — Parameters of IPF for the femur shaft
C C C
Scale Shape Slope
571 11,0 1,04
5.3 Leg
The IPF for the leg defines probability of tibia shaft fracture to a pedestrian subjected to the specific
load cases representative of the majority of real-world accidents as a function of maximum value of the
tibia bending moment measured by the aPLI.
Figure 2 presents the IPF for the leg. The injury probability function is shown in a solid line, with the
95 % confidence interval shown in dotted lines. The horizontal axis represents the maximum value
of the tibia bending moment measured by the aPLI, and the vertical axis represents the probability of
injury.
The IPF for the leg is given by the Formula (5):
C
Shape
 
Cx×
 
 SlopeaPLI 
P =−1exp − (5)
   
C
 Scale 
 
 
where
P is the injury probability for the tibia shaft of human;
C
is the parameter determined for the Weibull distribution for the human IPF for the tibia
Scale
shaft as described in B.3.3;
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ISO/TS 20459:2023(E)
C
is the parameter determined for the Weibull distribution for the human IPF for the tibia
Shape
shaft as described in B.3.3;
C
is the slope of the TF for the leg as described in A.2.4.4.2;
Slope
x
is the tibia BM measured by the aPLI in Nm.
aPLI
The parameters needed to define the IPF ( C , C and C ) for the function are described in
Scale Shape Slope
Table 4.
Key
X aPLI tibia BM [Nm]
Y probability of tibia shaft fracture
aPLI IPF for tibia shaft
95 % confidence interval
Figure 2 — IPF for the tibia shaft
Table 4 — Parameters of IPF for the tibia shaft
C C C
Scale Shape Slope
446 3,32 0,881
5.4 Knee
The IPF for the knee defines probability of complete failure of the MCL to a pedestrian subjected to the
specific load cases representative of the majority of real-world accidents as a function of maximum
value of MCL elongation measured by the aPLI.
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ISO/TS 20459:2023(E)
Figure 3 presents the IPF for the knee. The injury probability function is shown in a solid line, with the
95 % confidence interval shown in dotted lines. The horizontal axis represents the maximum value of
the MCL elongation measured by the aPLI, and the vertical axis represents the probability of injury.
The IPF for the knee is given by Formula (6):
2
 
Cx××C ××C −− ln −tC−
()
1 1
SlopeaPLITA1 TA2  μμ 
P = exp dt (6)
 
∫
2
0
t
C 2ππ
2C
 
σσ
σσ
 
where
P is the injury probability for the MCL of human;
C
is the parameter determined for the Log-Normal distribution for human IPFs for the MCL
μ
as described in A.2.3.4.3;
C
is the parameter determined for the Log-Normal distribution for human IPFs for the MCL
σ
as described in A.2.3.4.3;
C
is the slope of the TF for the knee as described in A.2.4.4.3;
Slope
C
is the correction factor for lower-limb posture and impact angle determined to adjust to
TA1
the real-world accident data as described in B.3.2.2.4;
C
is the correction factor for muscle tone determined to adjust to the real-world accident
TA2
data as described in B.3.2.3;
x
is the MCL elongation measured by the aPLI in mm.
aPLI
The parameters needed to define the IPF ( C ,, C CC, and C ) for the function are described
μσ SlopeTAT12A
in Table 5.
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ISO/TS 20459:2023(E)
Key
X aPLI MCL elongation [mm]
Y probability of MCL complete rupture
aPLI IPF for MCL complete rupture
95 % confidence interval
observed data
Figure 3 — IPF for the MCL complete rupture
Table 5 — Parameters of IPF for the MCL complete rupture
C C
C C C
μμ Slope
σσ TA1 TA2
3,34 0,291 1,14 0,72 0,90
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ISO/TS 20459:2023(E)
Annex A
(informative)

Rationale regarding background and methodology to develop IPFs
for the aPLI
A.1 Historical background
A.1.1 General
Although lower extremity injuries are not life-threatening, they are frequent and potentially disabling,
resulting in a substantial cost to the victims and society. The importance of preventing this type of
injuries is illustrated by the United Nation (UN) regulations that aim to mitigate lower extremity
injuries to pedestrians hit by the front-end of cars (See References [1] and [2]).
The UN regulations initially implemented the EEVC pedestrian legform impactor that simply consists
of rigid long bones and a deformable knee joint. In order to improve injury assessment capability, a
new impactor called the Flexible Pedestrian Legform Impactor (FlexPLI) has been developed and
implemented in the phase-2 of Reference [1].
Despite a number of improvements of its capability relative to the EEVC impactor, the FlexPLI still
lacks representation of the influence of the upper part of the body. To address technical issues with
the FlexPLI, including but not limited to the lack of upper body representation, the aPLI with the upper
mass attached to the top of the conventional pedestrian legform to compensate for the lack of the upper
body has been developed. In November 2014, two ISO projects were initiated to develop Technical
Specification (TSs) for "Road vehicles - Modified pedestrian legform impactor for tests of high bumper
vehicles" and "Road vehicles - Injury criteria and risk curves for a modified pedestrian legform
impactor for use with high bumper vehicles", and the aPLI task group (TG) was established by active
participants from research institutes, dummy and instruments manufacturers, governments and car
manufacturers. The aPLI TG has conducted extensive CAE studies to identify optimized specifications
of the aPLI by utilizing HBMs, SCMs and aPLI prototype models. Based on the specifications identified, a
physical version of aPLI SBL-A was fabricated and subjected to international round robin testing.
The aPLI TG also dedicated to their effort to discuss a methodology to develop IPFs. During the
discussion, two different methods were proposed and it was difficult to choose one of the two
proposed methods because both have pros and cons. A new idea taken to facilitate the discussion was
to develop ‘virtual IPFs’ by using parametric human body models (HBMs) with the variability in the
material property of a human body incorporated. The results of this analysis along with some other
consideration resulted in a decision of applying a TF to convert IPFs for human to those for the aPLI.
Due to the lack of sufficient biomechanical data, it was necessary to determine TFs based on the
results of computer simulations using HBMs to take various load cases into consideration. Multiple
HBMs with extensive validation were used to avoid potential bias in case one single HBM is employed.
The specifications of the latest version of the aPLI hardware with the bumper system installed at the
hip joint as defined in ISO/TS 20458 were represented by FE models and used in the analyses. Real
car models (RCMs) were also used to accurately represent geometric and stiffness characteristics
of car front-end structures. The use of multiple different HBMs, RCMs and impact locations all
...

© ISO #### – All rights reserved
ISO/TS 20459:202#(2022(E)
ISO TC 22/SC 36/WG 6
Secretariat: XXXX
Date: 2023-02
Road vehicles - Injury risk functions for advanced Pedestrian Legform
Impactorpedestrian legform impactor (aPLI) –

TS stage



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© ISO 202#,

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ISO/TS 20459:2023(E)
© ISO 2023, Published in Switzerland
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ISO/TS 20459:2023(E)
Contents
Foreword . 6
Introduction. 7
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 4
4.1 Symbols . 4
4.2 Abbreviated terms . 4
5 IPFs for aPLI . 5
5.1 General . 5
5.2 Thigh . 8
5.3 Leg . 10
5.4 Knee . 13
Annex A (informative) Rationale regarding background and methodology to develop IPFs
for aPLI . 17
Annex B (informative) Adjustment of IPFs for real-world relevance . 165
Annex C (informative) Supplemental data . 218
Annex D (informative) Influence of PMHS test data (dfbetas > 0,3) against IPFs for human . 219
Bibliography . 248

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ISO/TS 20459:2023(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
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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 of 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).
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Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT)), see
www.iso.org/iso/foreword.htmlthe following URL: .
The committee responsible for thisThis document iswas prepared by Technical Committee ISO/TC 22,
Road vehicles, Subcommittee SC 36, Safety and impact testing.
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.
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ISO/TS 20459:2023(E)
Introduction
This ISO/TS 20459document has been prepared on the basis of the existing injury probability functions
(IPFs) to be used with an advanced Pedestrian Legform Impactorpedestrian legform impactor (aPLI)
standard build level B (SBL-B). The purpose of the TS this document is to document the IPFs for an aPLI
in a form suitable and intended for worldwide harmonized use.
In 2014, ISO/TC 22/SC 36 initiated development of the aPLI hardware and associated IPFs started, with
the aim of defining a globally accepted next-generation pedestrian legform impactor with enhanced
biofidelity and injury assessment capability, along with its IPFs, suitable for harmonized use.
Participating in the development were research institutes, dummy and instrumentation manufacturers,
governments, and car manufacturers from around the world.
IPFs for aPLI specified in this document predict injury probability to specific regions of the lower limb of
a pedestrian that correspond to maximum values of injury metrics obtained by the aPLI in a subsystem
test, as described in UN R127 References [1] and UN GTR No.9 .[2]. As the IPFs do not provide any
threshold values, users will need to determine target injury probability, based on their specific needs, to
define injury assessment reference values to be used for their test protocol.
It is also important to note that the subsystem test procedure (STP) for pedestrian protection may not be
representative of pedestrian accidents for specific injury metrics, depending on their sensitivity to
pedestrian impact conditions such as lower-limb posture and muscle tone. The IPFs for aPLI have been
validated against accident data and some ideas to compensate for the discrepancy against accident data
are presented in . Annex B.
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TECHNICAL SPECIFICATION ISO/TS 20459:2023(E)

Road vehicles - Injury risk functions for advanced Pedestrian
Legform Impactorpedestrian legform impactor (aPLI)
1 Scope
This document provides definitions, symbols and injury probability functions (IPFs) for the thigh, leg and
knee intended to be used with an advanced Pedestrian Legform Impactorpedestrian legform impactor
(aPLI), a standardized pedestrian legform impactor with an upper mass for pedestrian subsystem testing
of road vehicles. They are applicable to impact tests using an aPLI at 11,1 m/s involving:
— vehicles of category M1, except vehicles with a maximum mass above 2 500 kg and which are derived
from N1 category vehicles and where the driver’s position, the R-point, is either forward of the front
axle or longitudinally rearwards of the front axle transverse centreline by a maximum of 1 100 mm;
— vehicles of category N1, except where the driver’s position, the R-point, is either forward of the front
axle or longitudinally rearwards of the front axle transverse centreline by maximum of 1 100 mm;
— impacts to the bumper test area defined by UN R127 References [1] and UN GTR No.9 [2];
— pedestrian subsystem tests involving use of a legform for the purpose of evaluating compliance with
vehicle safety standards.
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/TS 18506, Procedure to construct injury risk curves for the evaluation of road user protection in crash
tests
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology 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
adult
person who is sixteen years old or older
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ISO/TS 20459:2023(E)
3.2
advanced pedestrian legform impactor
(aPLI)
modified pedestrian legform impactor developed by ISO TC22/SC36/WG5 and WG6/aPLI Task Group,
which incorporates a mass representing the inertial effect of the upper part of a pedestrian body to
enhance biofidelity and injury assessment capability (3.10) of conventional pedestrian legforms
3.3
biofidelity
aspect of an advanced pedestrian legform impactor (aPLI) (3.2) capability to represent the impact
response of human subjects
3.4
BLE height
bonnet leading edge (BLE) height
height of the geometric trace of the upper most points of contact between a straight edge and the front-
end of a car
3.5
bumper test area
test area of the legform to bumper impact test
3.6
bumper system
component installed at the hip joint inside the upper mass composed of the bumper, the bumper mount
and the compression surface, designed to apply a force on the upper part of the femur in adduction to
enhance injury assessment capability of aPLI(3.10) of an advanced pedestrian legform impactor (aPLI)
(3.2)
3.7
EE method
energy-equivalent (EE) method
method of developing injury probability functions (IPFs) (3.11) for an advanced pedestrian legform
impactor (aPLI) (3.2) by transferring human injury values to those of an aPLI using the absorbed energy
3.8
high-bumper car
car with thea lower bumper reference line height (3.14) of 425 mm or more
3.9
hip joint
uniaxial joint that allows abduction and adduction and connects the upper mass with the lower limb
3.10
injury assessment capability
aspect of an advanced pedestrian legform impactor (aPLI) (3.2) capability to produce peak injury values
that correlate with those obtained from human body model impact simulations
3.11
IPF
injury probability function (IPF)
function which defines the relationship between a peak value of an injury metric and probability of injury
for a specific load case
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ISO/TS 20459:2023(E)
3.12
ISO metric
objective rating metric used in this Technical Specificationdocument to verify time histories of sensor
output against experimentally or computationally produced target time histories
3.13
low-bumper car
car with thea lower bumper reference line height (3.14) less than 425 mm
3.14
LBRL height
lower bumper reference line (LBRL) height
height of the geometric trace of the lower mostlowermost points of contact between a straight edge and
the bumper, measured from the ground
3.15
low-pass filter
filter which permits only low-frequency (100 Hz or less) oscillations
3.16
paired test method
method of developing injury probability functions (IPFs) (3.11) by correlating human injury occurrence
in a specific impact configuration with the injury value measured by an ATD subjected to the same impact
as detailed in ISO/TR 12350:2013
3.17
subsystem test
test to evaluate safety performance of cars where subsystem impactors representing individual body
regions of a pedestrian are propelled into a front end of a stationary car, in impact conditions
representing specific load cases in car-pedestrian accidents
3.18
transfer function
(TF)
linear regression function between human injury values predicted by human body models and advanced
pedestrian legform impactor (aPLI) (3.2) injury values
3.19
TF method
transfer-function (TF) method
method of developing injury probability functions (IPFs) (3.11) for an advanced pedestrian legform
impactor (aPLI) (3.2) by converting human IPFs to those of aPLI using corresponding transfer functions
(3.18)

ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at
— IEC Electropedia: available at http://www.electropedia.org/
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ISO/TS 20459:2023(E)
84 Symbols and abbreviated terms
8.14.1 Symbols
See .Table 1.
Table 1 — Symbols and their meanings
Symbol Meaning
Split Cells
Split Cells

C 𝐶𝐶 Parameter determined for the Weibull distribution for human IPFs
Scale
Scale
C 𝐶𝐶
Shape Parameter determined for the Weibull distribution for human IPFs
Shape
C 𝐶𝐶
Slope Slope of the transfer function
Slope
C 𝐶𝐶
µ µ Parameter determined for the Log-Normal distribution for human IPFs
C 𝐶𝐶
σ Parameter determined for the Log-Normal distribution for human IPFs
σ
C 𝐶𝐶
TA1 Correction factor determined to adjust to the real-world accident data
TA1
C 𝐶𝐶
TA2 Correction factor determined to adjust to the real-world accident data
TA2
F IPF for human
G Transfer function
I 𝐼𝐼 Injury metric for human
human
human
I 𝐼𝐼 Injury metric for an aPLI
aPLI
aPLI
P Injury probability of human
P 𝑃𝑃
adj Adjusted injury probability for the MCL
adj
x 𝑥𝑥
Value of the injury metric for an aPLI
aPLI aPLI
x 𝑥𝑥
Value of the injury metric for human
human human
8.24.2 Abbreviated terms
See .Table 2.
Table 2 — Abbreviated terms and their meanings
Abbreviation Meaning and their meanings
Split Cells
Split Cells

ACL Anterior Cruciate Ligament
aPLI advanced Pedestrian Legform Impactor
ATD Anthropometric Test Device
BLE Bonnet Leading Edge
BM Bending Moment
EE Energy Equivalent
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ISO/TS 20459:2023(E)
EEVC European Enhanced Vehicle-safety Committee
FE Finite Element
HBM Human Body Model
IPF Injury Probability Function
LBRL Lower Bumper Reference Line
MCL Medial Collateral Ligament
PCL Posterior Cruciate Ligament
PMHS Post Mortem Human Subjects
RCM Real Car Model
SCM Simplified Car Model
STP Subsystem Test Procedure
TF Transfer Function
TG Task Group
95 IPFs for an aPLI
9.15.1 General
The IPFs specified in this document are to be used with the aPLI for the thigh, leg and knee to predict the
probability of injuries to pedestrians when involved in real-world car-pedestrian accidents. The IPFs
provide a statistically derived relationship between the maximum values of injury metrics obtained from
a test conducted using an aPLI by following the subsystem test procedure (STP), and the probability of
injury to a corresponding body region of a pedestrian when subjected to load cases representative of the
majority of real-world accidents.
The specific load case represented by the subsystem legform test is described below:
th
— pedestrian size and weight: 175,1 cm and 76,7 kg representing a 50 percentile adult male
(Schneider et al. ) Reference [3]);
— impact speed: 11,1 m/s;
— impact direction: lateral-to-medial direction to a pedestrian lower limb;
— lower-limb posture: upright (vertical to the ground) with the knee fully extended;
— impact height: sole of the foot positioned 25 mm above the ground to represent a shoe sole height.
First, human IPFs were determined using human biomechanical data available from the literature. Data
obtained by the experiments conducted under the loading conditions equivalent to those specified in the
STP were referred to. The statistical method used to derive human IPFs follows that recommended by
ISO/TS 18506 with the covariates of pedestrian size, weight and age. The pedestrian size and weight were
determined from those specified in STP. The age was set at 60 years old that corresponds to the average
age of the subjects of the biomechanical data as this choice was found to provide the most reasonable set
of assumptions when the IPFs were fitted to the accident data. The recommended method estimates
parameters of any one of the Weibull, Log-Normal or Log-Logistic distribution (choose the one that best
fits to data) with survival analysis method. In this document, one of the three distributions (Weibull
distribution, Log-Normal distribution or Log-Logistic distribution) is used to define human IPFs for each
of the injury metrics. The formulae of the aPLI IPFs for these distributions are presented below.
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ISO/TS 20459:2023(E)
The injury probability when the Weibull distribution is applied: following Formula (1):
C
Shape
Cx× 𝑪𝑪
 𝐒𝐒𝐒𝐒𝐚𝐚𝐞𝐞𝐞𝐞
Slope aPLI 𝑪𝑪 ×𝒙𝒙
𝐒𝐒𝐒𝐒𝐒𝐒𝐞𝐞𝐞𝐞 𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚
P=1−−exp 𝑷𝑷 =𝟏𝟏−𝐞𝐞𝐞𝐞𝐞𝐞�−� � �

𝑪𝑪
𝐒𝐒𝐒𝐒𝐚𝐚𝐒𝐒𝐞𝐞
C
Scale


   ( )
(1)
where
P is the injury probability of human;
𝐶𝐶 is the parameter determined for the Weibull distribution for human IPFs;
Scale
𝐶𝐶 is the parameter determined for the Weibull distribution for human IPFs;
Shape
𝐶𝐶 is the slope of the transfer function (TF);
Slope
𝑥𝑥 is the value of the injury metric for aPLI.
aPLI
 P is the injury probability of human;
C
 is the parameter determined for the Weibull distribution for human IPFs;
Scale
 C is the parameter determined for the Weibull distribution for human IPFs;
Shape
 C is the slope of the transfer function (TF);
Slope

 x is the value of the injury metric for aPLI.
aPLI
The injury probability when the Log-Normal distribution is applied: following Formula (2):
2

𝟐𝟐
− ln −t C
C ×x ( )
11 𝑪𝑪 ×𝒙𝒙 −�𝐒𝐒𝐥𝐥𝒕𝒕−𝑪𝑪 �
Slope aPLI µ 𝟏𝟏 𝟏𝟏 𝛍𝛍
𝐒𝐒𝐒𝐒𝐒𝐒𝐞𝐞𝐞𝐞 𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚
Pt= exp d 𝑷𝑷 = ∫ 𝒆𝒆𝒙𝒙𝒆𝒆� �𝒅𝒅𝒕𝒕
 𝟐𝟐
𝟎𝟎
∫ 𝑪𝑪 √𝟐𝟐𝟐𝟐 𝒕𝒕 𝟐𝟐𝑪𝑪
2 𝝈𝝈 𝛔𝛔
0
t
C 2π 2C

σ σ

   ( )
(2)
where
P is the injury probability of human;
𝐶𝐶 is the parameter determined for the Log-Normal distribution for human IPFs;
µ
𝐶𝐶 is the parameter determined for the Log-Normal distribution for human IPFs;
σ
𝐶𝐶 is the slope of the TF;
Slope
𝑥𝑥 is the value of the injury metric for aPLI.
aPLI
 P is the injury probability of human;
 C is the parameter determined for the Log-Normal distribution for human IPFs;
µ
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ISO/TS 20459:2023(E)
C
 is the parameter determined for the Log-Normal distribution for human IPFs;
σ
 C is the slope of the TF;
Slope
 x is the value of the injury metric for the aPLI.
aPLI
The injury probability when the Log-Logistic distribution is applied: following Formula (3):
1
𝟏𝟏
𝑷𝑷 =
P =
−𝟏𝟏
−1
𝑪𝑪 ×𝒙𝒙
𝑪𝑪
𝐒𝐒𝐒𝐒𝐒𝐒𝐞𝐞𝐞𝐞 𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚 𝐒𝐒𝐒𝐒𝐚𝐚𝐞𝐞𝐞𝐞
𝟏𝟏+� �
C ×x
C 𝐞𝐞𝐞𝐞𝐞𝐞 (𝑪𝑪 )
Slope aPLI 𝐒𝐒𝐒𝐒𝐚𝐚𝐒𝐒𝐞𝐞
Shape
1 +

exp C
( )
Scale
  ( )
(3)
where
P is the injury probability of human;
𝐶𝐶 is the parameter determined for the Log-Logistic distribution for human IPFs;
Scale
𝐶𝐶 is the parameter determined for the Log-Logistic distribution for human IPFs;
Shape
𝐶𝐶 is the slope of the TF;
Slope
𝑥𝑥 is the value of the injury metric for aPLI.
aPLI
 P is the injury probability of human;
C
 is the parameter determined for the Log-Logistic distribution for human IPFs;
Scale
 C is the parameter determined for the Log-Logistic distribution for human IPFs;
Shape
 C is the slope of the TF;
Slope
x
 is the value of the injury metric for the aPLI.
aPLI
For each of the thigh, leg and knee, IPFs for a human body are then transferred to those of the aPLI using
a TF, which is a linear function between the maximum values of a human and aPLI injury metrics. Due to
the lack of biomechanical data, the TFs were determined from the results of computational impact
simulations using FE human body models (HBMs) and aPLI FE models in loading conditions specified in
the STP. Details of the human IPFs from which IPFs for the aPLI are derived can be found in Annex . A.2.3.
For the determination of TFs, see Annex A.2.4 for more details.
As the IPFs converted from human IPFs using TFs are for the specific load case defined in the STP, the
number of injuries calculated from each of the injury probabilities predicted by the IPFs were compared
with that of real-world accidents. The IPFs for the knee and the leg were compensated for the real-world
observations for the injury metrics showing a significant inconsistency with accident data. Details of the
compensation to real-world accidents can be found in .Annex B.
Supplemental information related to the TFs and IPFs for human areis provided in Annex C and ,Annex D,
respectively.
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ISO/TS 20459:2023(E)
9.25.2 Thigh
The IPF for the thigh defines probability of femur shaft fracture to a pedestrian subjected to the load cases
representative of the majority of real-world accidents as a function of maximum value of the femur
bending moment measured by the aPLI.
Figure 1 presents the IPF for the thigh. The injury probability function is shown in a solid line, with the
95 % confidence interval shown in dotted lines. The horizontal axis represents the maximum value of the
femur bending moment measured by the aPLI, and the vertical axis represents the probability of injury.
The IPF for the thigh is given by the following formula:Formula (4):
C
Shape

Cx× 𝑪𝑪
 𝐒𝐒𝐒𝐒𝐚𝐚𝐞𝐞𝐞𝐞
Slope aPLI 𝑪𝑪 ×𝒙𝒙
𝐒𝐒𝐒𝐒𝐒𝐒𝐞𝐞𝐞𝐞 𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚
P=1−−exp 𝑷𝑷 =𝟏𝟏−𝐞𝐞𝐞𝐞𝐞𝐞�−� � �

𝑪𝑪
𝐒𝐒𝐒𝐒𝐚𝐚𝐒𝐒𝐞𝐞
C
Scale


   ( )
(4)
where
P is the injury probability for the femur shaft of human;
𝐶𝐶 is the parameter determined for the Weibull distribution for the human IPF for the femur
Scale
shaft as described in Annex ;
𝐶𝐶 is the parameter determined for the Weibull distribution for the human IPF for the femur
Shape
shaft as described in Annex ;
𝐶𝐶 is the slope of the TF for the thigh as described in Annex ;
Slope
𝑥𝑥 is the femur BM measured by aPLI in Nm.
aPLI
The parameters needed to define the IPF (𝐶𝐶 , 𝐶𝐶 and 𝐶𝐶 ) for the function are described in .
Scale Shape Slope


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ISO/TS 20459:2023(E)

1
0.9
0.8
0.7
0.6
0.5
Y
0.4
0.3
0.2
0.1
0
0 100 200 300 400 500 600 700 800
X

A C D

Key
A aPLI IPF for femur shaft
C 95% confidence interval
D Observed data
X aPLI femur BM (Nm)
Y Probability of femur shaft fracture
9.2.1.1.1.1 Figure — IPF for the femur shaft

9.2.1.1.1.2 Table — Parameters of IPF for the femur shaft

𝑪𝑪 P is the injury probability for the femur shaft of human;𝑪𝑪
𝐒𝐒𝐒𝐒𝐚𝐚𝐞𝐞𝐞𝐞 𝐒𝐒𝐒𝐒𝐒𝐒𝐞𝐞𝐞𝐞
𝑪𝑪
𝐒𝐒𝐒𝐒𝐚𝐚𝐒𝐒
 C is the parameter determined for the Weibull distribution for the human IPF for the femur
Scale
shaft as described in A.2.3.4.1;
 C is the parameter determined for the Weibull distribution for the human IPF for the femur
Shape
shaft as described in A.2.3.4.1;
 C is the slope of the TF for the thigh as described in A.2.4.4.1;
Slope
x
 is the femur BM measured by the aPLI in Nm.
aPLI
The parameters needed to define the IPF ( C , C and C ) for the function are described in
Scale Shape Slope
Table 3.
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ISO/TS 20459:2023(E)

Key
X aPLI femur BM [Nm]
Y probability of femur shaft fracture
aPLI IPF for femur shaft

95 % confidence interval

observed data

Figure 1 — IPF for the femur shaft
Table 3 — Parameters of IPF for the femur shaft
C C C
Scale Shape Slope
571 11,0 1,04
9.35.3 Leg
The IPF for the leg defines probability of tibia shaft fracture to a pedestrian subjected to the specific load
cases representative of the majority of real-world accidents as a function of maximum value of the tibia
bending moment measured by the aPLI.
Figure 2 presents the IPF for the leg. The injury probability function is shown in a solid line, with the 95 %
confidence interval shown in dotted lines. The horizontal axis represents the maximum value of the tibia
bending moment measured by the aPLI, and the vertical axis represents the probability of injury.
The IPF for the leg is given by the following formula:Formula (5):
C
Shape
Cx× 𝑪𝑪
  𝐒𝐒𝐒𝐒𝐚𝐚𝐞𝐞𝐞𝐞
Slope aPLI 𝑪𝑪 ×𝒙𝒙
𝐒𝐒𝐒𝐒𝐒𝐒𝐞𝐞𝐞𝐞 𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚
P=1−−exp 𝑷𝑷 =𝟏𝟏−𝐞𝐞𝐞𝐞𝐞𝐞�−� � �
 
𝑪𝑪
𝐒𝐒𝐒𝐒𝐚𝐚𝐒𝐒𝐞𝐞
C
 Scale 


   ( )
(5)
where
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ISO/TS 20459:2023(E)
P is the injury probability for the tibia shaft of human;
𝐶𝐶 is the parameter determined for the Weibull distribution for the human IPF for the tibia
Scale
shaft as described in Annex ;
𝐶𝐶 is the parameter determined for the Weibull distribution for the human IPF for the tibia
Shape
shaft as described in Annex ;
𝐶𝐶 is the slope of the TF for the leg as described in Annex ;
Slope
𝑥𝑥 is the tibia BM measured by aPLI in Nm.
aPLI
The parameters needed to define the IPF (𝐶𝐶 , 𝐶𝐶 and 𝐶𝐶 ) for the function are described in .
Scale Shape Slope

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ISO/TS 20459:2023(E)


1
0,9
0,8
0,7
0,6
Y 0,5
0,4
0,3
0,2
0,1
0
0 100 200 300 400 500 600 700 800
X

A C

Key
A aPLI IPF for tibia shaft
C 95% confidence interval
X aPLI tibia BM (Nm)
Y Probability of tibia shaft fracture

9.3.1.1.1.1 Figure —IPF for the tibia shaft
9.3.1.1.1.2 Table — Parameters of IPF for the tibia shaft
𝑪𝑪 P is the injury probability for the tibia shaft of human;𝑪𝑪
𝐒𝐒𝐒𝐒𝐚𝐚𝐞𝐞𝐞𝐞 𝐒𝐒𝐒𝐒𝐒𝐒𝐞𝐞𝐞𝐞
𝑪𝑪
𝐒𝐒𝐒𝐒𝐚𝐚𝐒𝐒
 C is the parameter determined for the Weibull distribution for the human IPF for the tibia
Scale
shaft as described in B.3.3;
C
  is the parameter determined for the Weibull distribution for the human IPF for the tibia
Shape
shaft as described in B.3.3;
 C is the slope of the TF for the leg as described in A.2.4.4.2;
Slope
 x is the tibia BM measured by the aPLI in Nm.
aPLI
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ISO/TS 20459:2023(E)
The parameters needed to define the IPF ( C , C and C ) for the function are described in
Scale Shape Slope
Table 4.

Key
X aPLI tibia BM [Nm]
Y probability of tibia shaft fracture
aPLI IPF for tibia shaft

95 % confidence interval

Figure 2 —IPF for the tibia shaft
Table 4 — Parameters of IPF for the tibia shaft
C C C
Scale Shape Slope
446 3,32 0,881
9.45.4 Knee
The IPF for the knee defines probability of complete failure of the MCL to a pedestrian subjected to the
specific load cases representative of the majority of real-world accidents as a function of maximum value
of MCL elongation measured by the aPLI.
Figure 3 presents the IPF for the knee. The injury probability function is shown in a solid line, with the
95 % confidence interval shown in dotted lines. The horizontal axis represents the maximum value of the
MCL elongation measured by the aPL
...

TECHNICAL ISO/TS
SPECIFICATION 20459
First edition
Road vehicles — Injury risk functions
for advanced pedestrian legform
impactor (aPLI)
Véhicules routiers — Critères lésionnels et courbes de risques pour
l'impacteur en forme de jambe de piéton (aPLI).
PROOF/ÉPREUVE
Reference number
ISO/TS 20459:2023(E)
© ISO 2023

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ISO/TS 20459:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
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ISO/TS 20459:2023(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 . 4
5 IPFs for an aPLI .4
5.1 General . 4
5.2 Thigh . . 6
5.3 Leg. 7
5.4 Knee . . 8
Annex A (informative) Rationale regarding background and methodology to develop IPFs
for the aPLI .11
Annex B (informative) Adjustment of IPFs for real-world relevance . 103
Annex C (informative) Supplemental data . 133
Annex D (informative) Influence of PMHS test data (dfbetas > 0,3) against IPFs for human.134
Bibliography . 152
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ISO/TS 20459:2023(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.
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.
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ISO/TS 20459:2023(E)
Introduction
This document has been prepared on the basis of the existing injury probability functions (IPFs) to be
used with an advanced pedestrian legform impactor (aPLI) standard build level B (SBL-B). The purpose
of this document is to document the IPFs for an aPLI in a form suitable and intended for worldwide
harmonized use.
In 2014, development of the aPLI hardware and associated IPFs started, with the aim of defining
a globally accepted next-generation pedestrian legform impactor with enhanced biofidelity and
injury assessment capability, along with its IPFs, suitable for harmonized use. Participating in the
development were research institutes, dummy and instrumentation manufacturers, governments, and
car manufacturers from around the world.
IPFs for aPLI specified in this document predict injury probability to specific regions of the lower limb of
a pedestrian that correspond to maximum values of injury metrics obtained by the aPLI in a subsystem
test, as described in References [1] and [2]. As the IPFs do not provide any threshold values, users will
need to determine target injury probability, based on their specific needs, to define injury assessment
reference values to be used for their test protocol.
It is also important to note that the subsystem test procedure (STP) for pedestrian protection may not
be representative of pedestrian accidents for specific injury metrics, depending on their sensitivity to
pedestrian impact conditions such as lower-limb posture and muscle tone. The IPFs for aPLI have been
validated against accident data and some ideas to compensate for the discrepancy against accident data
are presented in Annex B.
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TECHNICAL SPECIFICATION ISO/TS 20459:2023(E)
Road vehicles — Injury risk functions for advanced
pedestrian legform impactor (aPLI)
1 Scope
This document provides definitions, symbols and injury probability functions (IPFs) for the thigh, leg
and knee intended to be used with an advanced pedestrian legform impactor (aPLI), a standardized
pedestrian legform impactor with an upper mass for pedestrian subsystem testing of road vehicles.
They are applicable to impact tests using an aPLI at 11,1 m/s involving:
— vehicles of category M1, except vehicles with a maximum mass above 2 500 kg and which are derived
from N1 category vehicles and where the driver’s position, the R-point, is either forward of the front
axle or longitudinally rearwards of the front axle transverse centreline by a maximum of 1 100 mm;
— vehicles of category N1, except where the driver’s position, the R-point, is either forward of the front
axle or longitudinally rearwards of the front axle transverse centreline by maximum of 1 100 mm;
— impacts to the bumper test area defined by References [1] and [2];
— pedestrian subsystem tests involving use of a legform for the purpose of evaluating compliance
with vehicle safety standards.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology 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
adult
person who is sixteen years old or older
3.2
advanced pedestrian legform impactor
aPLI
modified pedestrian legform impactor which incorporates a mass representing the inertial effect of
the upper part of a pedestrian body to enhance biofidelity and injury assessment capability (3.10) of
conventional pedestrian legforms
3.3
biofidelity
aspect of an advanced pedestrian legform impactor (aPLI) (3.2) capability to represent the impact
response of human subjects
1
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ISO/TS 20459:2023(E)
3.4
BLE height
bonnet leading edge height
height of the geometric trace of the upper most points of contact between a straight edge and the front-
end of a car
3.5
bumper test area
test area of the legform to bumper impact test
3.6
bumper system
component installed at the hip joint inside the upper mass composed of the bumper, the bumper mount
and the compression surface, designed to apply a force on the upper part of the femur in adduction to
enhance injury assessment capability (3.10) of an advanced pedestrian legform impactor (aPLI) (3.2)
3.7
EE method
energy-equivalent method
method of developing injury probability functions (IPFs) (3.11) for an advanced pedestrian legform
impactor (aPLI) (3.2) by transferring human injury values to those of an aPLI using the absorbed energy
3.8
high-bumper car
car with a lower bumper reference line height (3.14) of 425 mm or more
3.9
hip joint
uniaxial joint that allows abduction and adduction and connects the upper mass with the lower limb
3.10
injury assessment capability
aspect of an advanced pedestrian legform impactor (aPLI) (3.2) capability to produce peak injury values
that correlate with those obtained from human body model impact simulations
3.11
IPF
injury probability function
function which defines the relationship between a peak value of an injury metric and probability of
injury for a specific load case
3.12
ISO metric
objective rating metric used in this document to verify time histories of sensor output against
experimentally or computationally produced target time histories
3.13
low-bumper car
car with a lower bumper reference line height (3.14) less than 425 mm
3.14
LBRL height
lower bumper reference line height
height of the geometric trace of the lowermost points of contact between a straight edge and the
bumper, measured from the ground
3.15
low-pass filter
filter which permits only low-frequency (100 Hz or less) oscillations
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ISO/TS 20459:2023(E)
3.16
paired test method
method of developing injury probability functions (IPFs) (3.11) by correlating human injury occurrence
in a specific impact configuration with the injury value measured by an ATD subjected to the same
impact as detailed in ISO/TR 12350:2013
3.17
subsystem test
test to evaluate safety performance of cars where subsystem impactors representing individual
body regions of a pedestrian are propelled into a front end of a stationary car, in impact conditions
representing specific load cases in car-pedestrian accidents
3.18
transfer function
TF
linear regression function between human injury values predicted by human body models and advanced
pedestrian legform impactor (aPLI) (3.2) injury values
3.19
TF method
transfer-function method
method of developing injury probability functions (IPFs) (3.11) for an advanced pedestrian legform
impactor (aPLI) (3.2) by converting human IPFs to those of aPLI using corresponding transfer functions
(3.18)
4 Symbols and abbreviated terms
4.1 Symbols
See Table 1.
Table 1 — Symbols and their meanings
Symbol Meaning
C Parameter determined for the Weibull distribution for human IPFs
Scale
C
Parameter determined for the Weibull distribution for human IPFs
Shape
C
Slope of the transfer function
Slope
C
Parameter determined for the Log-Normal distribution for human IPFs
μ
C Parameter determined for the Log-Normal distribution for human IPFs
σ
C Correction factor determined to adjust to the real-world accident data
TA1
C Correction factor determined to adjust to the real-world accident data
TA2
F IPF for human
G Transfer function
I Injury metric for human
human
I Injury metric for an aPLI
aPLI
P Injury probability of human
P
Adjusted injury probability for the MCL
adj
x Value of the injury metric for an aPLI
aPLI
x Value of the injury metric for human
human
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ISO/TS 20459:2023(E)
4.2 Abbreviated terms
See Table 2.
Table 2 — Abbreviated terms and their meanings
Abbreviation Meaning
ACL Anterior Cruciate Ligament
aPLI advanced Pedestrian Legform Impactor
ATD Anthropometric Test Device
BLE Bonnet Leading Edge
BM Bending Moment
EE Energy Equivalent
EEVC European Enhanced Vehicle-safety Committee
FE Finite Element
HBM Human Body Model
IPF Injury Probability Function
LBRL Lower Bumper Reference Line
MCL Medial Collateral Ligament
PCL Posterior Cruciate Ligament
PMHS Post Mortem Human Subjects
RCM Real Car Model
SCM Simplified Car Model
STP Subsystem Test Procedure
TF Transfer Function
TG Task Group
5 IPFs for an aPLI
5.1 General
The IPFs specified in this document are to be used with the aPLI for the thigh, leg and knee to predict
the probability of injuries to pedestrians when involved in real-world car-pedestrian accidents. The
IPFs provide a statistically derived relationship between the maximum values of injury metrics
obtained from a test conducted using an aPLI by following the subsystem test procedure (STP), and
the probability of injury to a corresponding body region of a pedestrian when subjected to load cases
representative of the majority of real-world accidents.
The specific load case represented by the subsystem legform test is described below:
th
— pedestrian size and weight: 175,1 cm and 76,7 kg representing a 50 percentile adult male (Reference
[3]);
— impact speed: 11,1 m/s;
— impact direction: lateral-to-medial direction to a pedestrian lower limb;
— lower-limb posture: upright (vertical to the ground) with the knee fully extended;
— impact height: sole of the foot positioned 25 mm above the ground to represent a shoe sole height.
First, human IPFs were determined using human biomechanical data available from the literature. Data
obtained by the experiments conducted under the loading conditions equivalent to those specified in
the STP were referred to. The statistical method used to derive human IPFs follows that recommended
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ISO/TS 20459:2023(E)
by ISO/TS 18506 with the covariates of pedestrian size, weight and age. The pedestrian size and weight
were determined from those specified in STP. The age was set at 60 years old that corresponds to the
average age of the subjects of the biomechanical data as this choice was found to provide the most
reasonable set of assumptions when the IPFs were fitted to the accident data. The recommended
method estimates parameters of any one of the Weibull, Log-Normal or Log-Logistic distribution
(choose the one that best fits to data) with survival analysis method. In this document, one of the three
distributions (Weibull distribution, Log-Normal distribution or Log-Logistic distribution) is used to
define human IPFs for each of the injury metrics. The formulae of the aPLI IPFs for these distributions
are presented below.
The injury probability when the Weibull distribution is applied following Formula (1):
C
Shape
 
Cx×
 
 SlopeaPLI 
P =−1exp − (1)
   
C
 Scale 
 
 
where
P is the injury probability of human;
C
is the parameter determined for the Weibull distribution for human IPFs;
Scale
C
is the parameter determined for the Weibull distribution for human IPFs;
Shape
C
is the slope of the transfer function (TF);
Slope
x
is the value of the injury metric for aPLI.
aPLI
The injury probability when the Log-Normal distribution is applied following Formula (2):
2
 
−− ln −tC−
Cx×
()
1 SlopeaPLI1  μμ 
P = exp dt (2)
 
∫
2
0
t
C 2ππ
2C
 
σσ
σσ
 
where
P is the injury probability of human;
C
is the parameter determined for the Log-Normal distribution for human IPFs;
μ
C
is the parameter determined for the Log-Normal distribution for human IPFs;
σ
C
is the slope of the TF;
Slope
x
is the value of the injury metric for the aPLI.
aPLI
The injury probability when the Log-Logistic distribution is applied following Formula (3):
1
P = (3)
−−1
C ×x
 C
SlopeaPLI
Shape
1++
 
exp()C
 Scale 
where
P is the injury probability of human;
C
is the parameter determined for the Log-Logistic distribution for human IPFs;
Scale
C
is the parameter determined for the Log-Logistic distribution for human IPFs;
Shape
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ISO/TS 20459:2023(E)
C
is the slope of the TF;
Slope
x
is the value of the injury metric for the aPLI.
aPLI
For each of the thigh, leg and knee, IPFs for a human body are then transferred to those of the aPLI using
a TF, which is a linear function between the maximum values of a human and aPLI injury metrics. Due
to the lack of biomechanical data, the TFs were determined from the results of computational impact
simulations using FE human body models (HBMs) and aPLI FE models in loading conditions specified
in the STP. Details of the human IPFs from which IPFs for the aPLI are derived can be found in A.2.3. For
the determination of TFs, see A.2.4 for more details.
As the IPFs converted from human IPFs using TFs are for the specific load case defined in the STP, the
number of injuries calculated from each of the injury probabilities predicted by the IPFs were compared
with that of real-world accidents. The IPFs for the knee and the leg were compensated for the real-world
observations for the injury metrics showing a significant inconsistency with accident data. Details of
the compensation to real-world accidents can be found in Annex B.
Supplemental information related to the TFs and IPFs for human is provided in Annex C and Annex D,
respectively.
5.2 Thigh
The IPF for the thigh defines probability of femur shaft fracture to a pedestrian subjected to the load
cases representative of the majority of real-world accidents as a function of maximum value of the
femur bending moment measured by the aPLI.
Figure 1 presents the IPF for the thigh. The injury probability function is shown in a solid line, with the
95 % confidence interval shown in dotted lines. The horizontal axis represents the maximum value of
the femur bending moment measured by the aPLI, and the vertical axis represents the probability of
injury.
The IPF for the thigh is given by Formula (4):
C
Shape
 
Cx×
 
 SlopeaPLI 
P =−1exp − (4)
   
C
  Scale  
 
where
P is the injury probability for the femur shaft of human;
C
is the parameter determined for the Weibull distribution for the human IPF for the femur
Scale
shaft as described in A.2.3.4.1;
C
is the parameter determined for the Weibull distribution for the human IPF for the femur
Shape
shaft as described in A.2.3.4.1;
C
is the slope of the TF for the thigh as described in A.2.4.4.1;
Slope
x
is the femur BM measured by the aPLI in Nm.
aPLI
The parameters needed to define the IPF ( C , C and C ) for the function are described in
Scale Shape Slope
Table 3.
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ISO/TS 20459:2023(E)
Key
X aPLI femur BM [Nm]
Y probability of femur shaft fracture
aPLI IPF for femur shaft
95 % confidence interval
observed data
Figure 1 — IPF for the femur shaft
Table 3 — Parameters of IPF for the femur shaft
C C C
Scale Shape Slope
571 11,0 1,04
5.3 Leg
The IPF for the leg defines probability of tibia shaft fracture to a pedestrian subjected to the specific
load cases representative of the majority of real-world accidents as a function of maximum value of the
tibia bending moment measured by the aPLI.
Figure 2 presents the IPF for the leg. The injury probability function is shown in a solid line, with the
95 % confidence interval shown in dotted lines. The horizontal axis represents the maximum value
of the tibia bending moment measured by the aPLI, and the vertical axis represents the probability of
injury.
The IPF for the leg is given by the Formula (5):
C
Shape
 
Cx×
 
 SlopeaPLI 
P =−1exp − (5)
   
C
 Scale 
 
 
where
P is the injury probability for the tibia shaft of human;
C
is the parameter determined for the Weibull distribution for the human IPF for the tibia
Scale
shaft as described in B.3.3;
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ISO/TS 20459:2023(E)
C
is the parameter determined for the Weibull distribution for the human IPF for the tibia
Shape
shaft as described in B.3.3;
C
is the slope of the TF for the leg as described in A.2.4.4.2;
Slope
x
is the tibia BM measured by the aPLI in Nm.
aPLI
The parameters needed to define the IPF ( C , C and C ) for the function are described in
Scale Shape Slope
Table 4.
Key
X aPLI tibia BM [Nm]
Y probability of tibia shaft fracture
aPLI IPF for tibia shaft
95 % confidence interval
Figure 2 — IPF for the tibia shaft
Table 4 — Parameters of IPF for the tibia shaft
C C C
Scale Shape Slope
446 3,32 0,881
5.4 Knee
The IPF for the knee defines probability of complete failure of the MCL to a pedestrian subjected to the
specific load cases representative of the majority of real-world accidents as a function of maximum
value of MCL elongation measured by the aPLI.
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ISO/TS 20459:2023(E)
Figure 3 presents the IPF for the knee. The injury probability function is shown in a solid line, with the
95 % confidence interval shown in dotted lines. The horizontal axis represents the maximum value of
the MCL elongation measured by the aPLI, and the vertical axis represents the probability of injury.
The IPF for the knee is given by Formula (6):
2
 
Cx××C ××C −− ln −tC−
()
1 1
SlopeaPLITA1 TA2  μμ 
P = exp dt (6)
 
∫
2
0
t
C 2ππ
2C
 
σσ
σσ
 
where
P is the injury probability for the MCL of human;
C
is the parameter determined for the Log-Normal distribution for human IPFs for the MCL
μ
as described in A.2.3.4.3;
C
is the parameter determined for the Log-Normal distribution for human IPFs for the MCL
σ
as described in A.2.3.4.3;
C
is the slope of the TF for the knee as described in A.2.4.4.3;
Slope
C
is the correction factor for lower-limb posture and impact angle determined to adjust to
TA1
the real-world accident data as described in B.3.2.2.4;
C
is the correction factor for muscle tone determined to adjust to the real-world accident
TA2
data as described in B.3.2.3;
x
is the MCL elongation measured by the aPLI in mm.
aPLI
The parameters needed to define the IPF ( C ,, C CC, and C ) for the function are described
μσ SlopeTAT12A
in Table 5.
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ISO/TS 20459:2023(E)
Key
X aPLI MCL elongation [mm]
Y probability of MCL complete rupture
aPLI IPF for MCL complete rupture
95 % confidence interval
observed data
Figure 3 — IPF for the MCL complete rupture
Table 5 — Parameters of IPF for the MCL complete rupture
C C
C C C
μμ Slope
σσ TA1 TA2
3,34 0,291 1,14 0,72 0,90
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ISO/TS 20459:2023(E)
Annex A
(informative)

Rationale regarding background and methodology to develop IPFs
for the aPLI
A.1 Historical background
A.1.1 General
Although lower extremity injuries are not life-threatening, they are frequent and potentially disabling,
resulting in a substantial cost to the victims and society. The importance of preventing this type of
injuries is illustrated by the United Nation (UN) regulations that aim to mitigate lower extremity
injuries to pedestrians hit by the front-end of cars (See References [1] and [2]).
The UN regulations initially implemented the EEVC pedestrian legform impactor that simply consists
of rigid long bones and a deformable knee joint. In order to improve injury assessment capability, a
new impactor called the Flexible Pedestrian Legform Impactor (FlexPLI) has been developed and
implemented in the phase-2 of Reference [1].
Despite a number of improvements of its capability relative to EEVC impactor, FlexPLI still lacks
representation of the influence of the upper part of the body. To address technical issues with FlexPLI,
including but not limited to the lack of upper body representation, the aPLI with the upper mass attached
to the top of the conventional pedestrian legform to compensate for the lack of the upper body has been
developed. In November 2014, two ISO projects were initiated to develop Technical Specification (TSs)
for "Road vehicles - Modified pedestrian legform impactor for tests of high bumper vehicles" and "Road
vehicles - Injury criteria and risk curves for a modified pedestrian legform impactor for use with high
bumper vehicles", and the aPLI task group (TG) was established by active participants from research
institutes, dummy and instruments manufacturers, governments and car manufacturers. The aPLI TG
has conducted extensive CAE studies to identify optimized specifications of the aPLI by utilizing HBMs,
SCMs and aPLI prototype models. Based on the specifications identified, a physical version of aPLI
SBL-A was fabricated and subjected to international round robin testing.
The aPLI TG continued the discussion of a methodology to develop IPFs, however, it was difficult to
choose one of the two proposed methods because both have pros and cons. A new idea taken to facilitate
the discussion was to develop ‘virtual IPFs’ by using parametric human body models (HBMs) with the
variability in the material property of a human body incorporated. The results of this analysis along
with some other consideration resulted in a decision of applying a TF to convert IPFs for human to those
for the aPLI.
Due to the lack of sufficient biomechanical data, it was necessary to determine TFs based on the
results of computer simulations using HBMs to take various load cases into consideration. Multiple
HBMs with extensive validation were used to avoid potential bias in case one single HBM is employed.
The specifications of the latest version of the aPLI hardware with the bumper system installed at the
hip joint as defined in ISO/TS 20458 were represented by FE models and used in the analyses. Real
car models (RCMs) were also used to accurately represent geometric and stiffness characteristics
of car front-end structures. The use of multiple different HBMs, RCMs and i
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