ISO 12353-1:2020

INTERNATIONAL
ISO
STANDARD
12353-1
Second edition
NORME
Deuxième édition
2020-01
INTERNATIONALE
Road vehicles — Traffic accident
analysis —
Part 1:
Vocabulary
Véhicules routiers — Analyse
des accidents de la circulation —
Partie 1:
Vocabulaire
Reference number
Numéro de référence
©
ISO 2020
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2020
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Published in Switzerland/Publié en Suisse
ii © ISO 2020 – All rights reserved/Tous droits réservés

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
Normative references . 1
Terms related to classification and inclusion . 1
4 Terms related to accident-descriptive elements and data collection.3
5 Terms related to crash analysis and reconstruction .13
Terms related to aggregate data analysis and interpretation .19
Annex A (informative) Fundamental road terms.21
Bibliography
.............................................................................................................................................................................................................................24
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/d irectives).
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/p atents).
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/f oreword. html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 36,
Safety and impact testing.
This second edition cancels and replaces the first edition (ISO 12353-1:2002), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— Revision of the following terms and/or definitions: 3.8, 3.13, 3.14, 4.1, 4.2.5, 4.2.20, 4.2.21, 4.2.21.1,
4.2.21.3, 4.2.21.3.1, 4.3.1, 4.3.7, 4.3.14.5, 4.3.16, 4.3.18, 4.3.22 (old deleted), 4.3.23, 5.1, 5.2, 5.5, 5.16,
5.18, 5.22.2, 5.26, 5.27, 5.28, 5.31, 5.34, and 5.40.1;
— Table A.1;
— Removal of A.3;
— Redrawn figures, and;
— Added references in Bibliography.
A list of all parts in the ISO 12353 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 2020 – All rights reserved/Tous droits réservés

Introduction
The various clauses of this document are based on a model of the accident analysis process as outlined
in Figure 1.
NOTE The numbers in parentheses correspond to clauses in this document.
Figure 1 — Road traffic accident analysis
INTERNATIONAL STANDARD ISO 12353-1:2020(E/F)
Road vehicles — Traffic accident analysis —
Part 1:
Vocabulary
1 Scope
This document establishes a vocabulary relating to the investigation and analysis of road traffic
accidents and to the application of accident data.
It also lists other, commonly used terms in the domain.
NOTE Additional terms and definitions, related to configuration aspects of road vehicle collisions, can be
found in ISO 6813.
2 Normative references
There are no normative references in this document.
3 Terms related to classification and inclusion
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 http:// www .electropedia .org/
3.1
road vehicle accident
unintended event that involves at least one road vehicle (4.3) in motion and leads to personal injury
(4.4.6) or property damage, or both
3.2
accident classification
classification of road vehicle accidents (3.1) according to a predetermined classification system
Note 1 to entry: There is no common and universally useful classification of accident types. Several systems have
proven useful in accident research and analysis, for example:
— accident classification by vehicle type,
— accident classification by injury severity (4.4.6.2),
— accident classification by damage severity,
— accident classification by number of vehicles,
— accident classification by first harmful event (5.26), and
— accident classification by location.
Attention is here drawn to some common terms used for accident classification.
Note 2 to entry: See 5.26 for definition of first harmful event.
3.3
injury accident
road vehicle accident (3.1) in which at least one road user (4.4) sustains an injury (4.4.6)
3.3.1
fatal accident
injury accident (3.3) in which at least one road user (4.4) sustains a fatal injury (4.4.6)
3.4
damage-only accident
property damage accident
road vehicle accident (3.1) in which the only outcome is damage to vehicles, or other property, with no
injury (4.4.6)
3.5
on-road accident
road vehicle accident (3.1) in which the first harmful event (5.26) occurs on the road
3.6
off-road accident
road vehicle accident (3.1) in which the first harmful event (5.26) occurs off the road
3.7
towaway accident
road vehicle accident (3.1) in which at least one vehicle is removed from the scene for reasons of
vehicle damage
3.8
single-vehicle accident
road vehicle accident (3.1) in which only one vehicle is involved
3.9
multi-vehicle accident
road vehicle accident (3.1) in which more than one vehicle is involved
3.10
accident-involved vehicle
vehicle involved in a road vehicle accident (3.1)
3.11
injury vehicle
accident-involved vehicle (3.10) in (or on) which at least one vehicle occupant sustains an injury (4.4.6)
3.11.1
fatal vehicle
injury vehicle (3.11) in (or on) which at least one vehicle occupant sustains a fatal injury (4.4.6)
3.12
non-injury vehicle
accident-involved vehicle (3.10) in (or on) which no vehicle occupant sustains an injury (4.4.6)
3.12.1
non-fatal vehicle
accident-involved vehicle (3.10) in (or on) which no vehicle occupant sustains a fatal injury (4.4.6)
3.13
damaged vehicle
vehicle involved sustaining damage
2 © ISO 2020 – All rights reserved/Tous droits réservés

3.14
undamaged vehicle
vehicle involved not sustaining damage
3.1.15
towaway vehicle
vehicle involved in a towaway accident (3.7) and removed from the scene for reasons of vehicle damage
3.16
non-towaway vehicle
vehicle involved in a towaway accident (3.7) and not removed from the scene for reasons of vehicle damage
3.17
inclusion criteria
sampling criteria
principle of evaluation of scope and coverage of an accident investigation (4.1) referring to different aspects
Note 1 to entry: An aspect of an accident investigation could be a road user (4.4), vehicle, injury (4.4.6) or fatality
(4.4.10.1), traffic environment or property damage.
3.18
sampling unit
combination of inclusion criteria (3.17) used for selection of data
EXAMPLE Injured passenger car drivers (4.4.1.2).
3.19
data source
origin of data in terms of time and type of investigation, type of institution or organization, and type
of record
4 Terms related to accident-descriptive elements and data collection
4.1
accident investigation
acquisition and documentation of factual information regarding an accident
Note 1 to entry: An accident investigation can include on-scene elements, elements collected retrospectively, or
both these.
4.1.1
first-level investigation
accident investigation (4.1) conducted by an investigator without specialized knowledge
4.1.2
in-depth investigation
accident investigation (4.1) conducted by an investigator with specialized knowledge
Note 1 to entry: An in-depth investigation covers one or more aspects of an accident in more detail than a first
level investigation.
4.1.3
multidisciplinary investigation
accident investigation (4.1) conducted by a team of investigators with specialized knowledge
encompassing several professional disciplines
4.1.4
self-reported investigation
accident investigation (4.1) based on data submitted by a person involved in an accident
4.1.5
on-scene investigation
accident investigation (4.1) conducted at the accident scene (4.2) with the purpose of collecting on-scene
information before physical evidence (e.g. the vehicles involved) has been removed
4.2
accident scene
area of a traffic accident before the vehicles and people involved have left
4.2.1
accident site
geographic location of the accident scene (4.2)
Note 1 to entry: The accident site may be given as exact coordinates [see point of impact (5.23)] or in a less
detailed way.
4.2.2
road category
trafficway category
subdivision of road, with respect to a predetermined set of parameters
Note 1 to entry: A road may be categorized by a description of the following parameters:
— main function (long distance, local, parking lot, etc.);
— size (width, number of lanes, etc.);
— separation level (vertical or horizontal);
— access restrictions (from adjacent areas);
— type of surface;
— design standard;
— road user (4.4) preferences or restrictions (allowed or prohibited traffic).
If this method is not applicable, a definition according to other relevant standards could be accepted, provided
that the reference source is given. For more details, see Annex A.
4.2.3
roadside
area adjoining the outer edge of the road
Note 1 to entry: See Figure A.1.
4.2.4
median strip, US
central reservation, GB
median
dividing strip
area separating two roadways
Note 1 to entry: See Figure A.1.
4.2.5
traffic island
facility in an intersection, gore (see Table A.2), etc., designed to secure a safe and smooth passing of
vehicles or to ensure the safe crossing of pedestrians (4.4.2)
4 © ISO 2020 – All rights reserved/Tous droits réservés

4.2.6
bicycle way, GB
bikeway, US
part of a trafficway specifically designated as being open for pedal cycle travel
4.2.7
footpath, GB
pavement, GB
sidewalk, US
paved strip adjacent to the roadway intended for pedestrian (4.4.2) use
4.2.8
kerb, GB
curb, US
stone or concrete edging separating a road from a pavement (4.2.7) or a path
4.2.9
pedestrian crossing, GB
crosswalk, US
part of a road indicated for pedestrian crossing
4.2.10
road alignment
top view (plan view) of road geometry
4.2.11
road profile
longitudinal side view of road geometry
4.2.12
road cross-section
transverse view of road geometry
4.2.13
horizontal curve
curve in the horizontal plane
4.2.14
vertical curve
curve in the vertical plane
Note 1 to entry: A vertical curve can be either a hill or a valley.
4.2.15
road condition
status of maintenance and condition of a road surface
EXAMPLE Descriptions of maintenance: smooth, pitted, rough; descriptions of road surface: dry, wet,
snowy, icy.
4.2.16
visibility conditions
conditions that may possibly affect visibility for the driver (4.4.1.2)
EXAMPLE Conditions that affect visibility are weather and light conditions, dirt on the windscreen, objects
blocking the view, etc.
4.2.17
traffic control
systematic or concentrative control of the traffic flow
Note 1 to entry: The traffic control can be composed of traffic signals, traffic-control signs (including markings
on the road), other traffic-control facilities (traffic-information warning device), median barriers, etc.
4.2.18
speed limit
maximum speed allowed on a road
4.2.19
roadside object
roadside furniture
roadside appurtenance
natural or manufactured object at the roadside (4.2.3)
EXAMPLE Crushable lattice light column (fixed, deformable roadside object); rigid pole with a break-away
pole footing (non-fixed, non-deformable roadside object).
Note 1 to entry: A roadside object can be fixed, non-fixed, deformable or non-deformable.
4.2.20
rest position
position where a vehicle or a road user (4.4) comes to a final stop after a road vehicle accident (3.1)
4.2.21
trace mark
mark left at the accident scene (4.2) showing relative contact during the road vehicle accident (3.1)
Note 1 to entry: The term "imprint" is sometimes used as a synonym to "trace mark".
EXAMPLE Scrape mark, scratch mark, gouge mark.
4.2.21.1
transfer mark
trace mark (4.2.21) caused by parts by transferring material from a vehicle onto another surface
4.2.21.2
critical speed mark
trace mark (4.2.21) caused by a tire when the tire does not track parallel to the leading front tire in a
turning manœuvre
Note 1 to entry: In a normal turn, the rear tire tracks inside and parallel to the leading front tire.
4.2.21.3
tire mark
tire friction mark
trace mark (4.2.21) caused by tire
EXAMPLE Scuffs, skids (5.34).
4.2.21.3.1
skid mark
tire mark (4.2.21.3) made by a wheel that is sliding without rotation
4.2.21.3.1.1
skip-skid mark
periodic non-continuous skid mark (4.2.21.3.1)
4.2.21.3.2
acceleration mark
tire mark (4.2.21.3) caused by an accelerating vehicle
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4.2.21.3.3
yaw mark
tire mark (4.2.21.3) caused by a sideways slip while the vehicle undergoes a yaw (5.38)
4.2.21.3.4
scuff mark
tire mark (4.2.21.3) made by a tire that is both rotating and slipping on a road or other surface
EXAMPLE Acceleration scuff, impact scuff, flat tire marks.
4.3
road vehicle
vehicle designed to operate on a road
4.3.1
pillar
reinforced vertical structure along the side of a passenger car designed to strengthen the occupant
compartment
Note 1 to entry: The pillars are named A-pillar, B-pillar, C-pillar, etc. from the windscreen and backwards. See
Figure 2.
Note 2 to entry: The term "post" is sometimes used instead of "pillar". SAE R-397 uses "post" for the lower part,
below window height.
Letters refer to names of pillars, A–D.
Figure 2 — Designation of pillars
4.3.2
rocker panel
sill
reinforced structure that passes below the doors and pillars (4.3.1) along the length of the occupant
compartment of a passenger car
4.3.3
roof side rail
reinforced structure along the top of the pillars (4.3.1) on the sides of a passenger car
4.3.4
upper beam, GB
header, US
reinforced structure above the windscreen (windshield) or the rear window of a passenger car
4.3.5
original equipment
equipment provided by the vehicle manufacturer
4.3.6
post-mounted equipment
equipment installed on a vehicle after production
4.3.6.1
aftermarket equipment
post-mounted equipment (4.3.6) unspecified by the manufacturer
4.3.7
primary vehicle safety
active safety
crash avoidance
vehicle system and features designated to avoid and reduce the occurrence of road vehicle accidents (3.1)
EXAMPLE Electronic stability control, autonomous emergency braking.
4.3.8
secondary vehicle safety
passive safety
crash protection
vehicle system and features designed to reduce the injury (4.4.6) consequences of a road vehicle
accident (3.1)
EXAMPLE Restraint systems (4.3.9), high penetration-resistant windshields.
4.3.9
restraint system
system designed to protect a vehicle occupant in the event of a collision
4.3.9.1
active restraint
manual restraint
restraint system (4.3.9) that relies on the action of its user
4.3.9.2
passive restraint
automatic restraint
restraint system (4.3.9) that does not rely on the action of its user
EXAMPLE Airbag.
4.3.9.3
supplementary restraint
restraint intended for use in combination with another restraint system (4.3.9)
EXAMPLE An airbag in combination with a three-point belt.
4.3.10
exterior damage description
description of exterior damage according to agreed rules
Note 1 to entry: Generally, SAE J224 (CDC) or J1301 (TDC) should be used.
8 © ISO 2020 – All rights reserved/Tous droits réservés

4.3.11
collision deformation classification
CDC
classification of the extent of a car or light truck contact deformation caused by a road vehicle accident (3.1)
Note 1 to entry: The collision deformation classification is presented as a structured combination of seven
alphanumeric characters (see SAE J224).
4.3.12
truck deformation classification
TDC
classification of the extent of a heavy vehicle contact deformation caused by a road vehicle accident (3.1)
Note 1 to entry: The truck deformation classification is presented as a structured combination of seven
alphanumeric characters (see SAE J1301).
4.3.13
wrap around distance
WAD
in a vehicle-pedestrian impact, shortest contour distance from the ground to the head impact against
the vehicle, measured on the vehicle front structure
4.3.14
crush
deformation
distortion of a vehicle from its original dimensions
4.3.14.1
dynamic crush
maximum deformation during the impact phase (5.8), total of restitutional and residual crush (4.3.14.3)
4.3.14.2
maximum crush
greatest amount of (dynamic or residual) crush to which a vehicle is subjected, measured either at right
angles to the vehicle surface or, sometimes, along the line of the principal direction of force
4.3.14.3
residual crush
crush (4.3.14) remaining when all parts of a vehicle have ceased moving, and after any restitution,
following impact
4.3.14.4
elastic crush
restitutional crush
portion of dynamic crush (4.3.14.1) recovered after the collision force is removed
Note 1 to entry: This is equal to the maximum crush (4.3.14.2) less the residual crush (4.3.14.3).
4.3.14.5
bowing
bananaing
bending of a vehicle along a principal axis caused by a side impact
4.3.15
crush profile
series of measurements across the damaged area that describe the damage pattern
4.3.16
end shifting
amount of lateral movement of the front or rear end of a passenger car following an oblique impact or
side impact
4.3.17
area of direct crush
area of direct impact
damaged area of a vehicle that has come into contact with the object that struck the vehicle
4.3.18
area of indirect crush
area of induced crush
damaged area which has not come into contact with the object that struck the vehicle
4.3.19
post-crash damage
all damage that occurred to a vehicle after it came to rest after an accident, as a result of human
intervention
Note 1 to entry: This includes damage resulting from rescue, towing, and salvage operations.
4.3.20
mass at impact
total mass of a vehicle, including occupants and luggage, at the time of impact
4.3.20.1
effective mass at impact
mass at impact (4.3.20) minus that portion of the mass of unrestrained vehicle occupants and luggage
not contributing to the residual crush (4.3.14.3)
4.3.21
interior damage description
description, preferably in words, of a vehicle interior crush (4.3.14)
EXAMPLE Deformation, displacement, separation, intrusion, penetration.
4.3.22
occupant compartment intrusion
reduction of space (dynamic or residual) of the occupant compartment caused by external influences
4.3.23
interior component displacement
relative change of position (4.4.5.1) of an interior component due to a road vehicle accident (3.1)
4.4
road user
person on the road
4.4.1
vehicle occupant
road user (4.4) in or on a vehicle
Note 1 to entry: Vehicle rider (4.4.1.1) is included in the concept of vehicle occupant.
4.4.1.1
vehicle rider
vehicle occupant riding on a vehicle
EXAMPLE Motorcyclist, moped rider, bicyclist.
4.4.1.2
driver
vehicle occupant in actual physical control of a vehicle, or who was in physical control before that
control was lost
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4.4.1.3
passenger
vehicle occupant other than the driver (4.4.1.2)
4.4.1.4
out-of-position occupant
vehicle occupant not in a designated seat position (4.4.5.4), or in a seating posture (4.4.5.2) with the
potential of interacting adversely with any restraint system (4.3.9)
4.4.2
pedestrian
road user (4.4) other than a vehicle occupant
4.4.3
road user category
categorization of road users (4.4) with respect to their functions in the traffic or vehicle
4.4.4
road user characteristic
attribute describing a road user (4.4) before, during or after a road vehicle accident (3.1)
4.4.4.1
physical characteristic
attribute describing physical features of a road user (4.4)
EXAMPLE Age, sex, height, mass.
4.4.4.2
socio-economic characteristic
attribute describing a socio-economic feature of a road user (4.4)
EXAMPLE Marital status, profession, education.
4.4.4.3
training and experience
formal competence in driving, further education and experience of driving, including factors such as
offence records and accident history
4.4.4.4
medical and mental condition
full health, or deviation from full health, including use of compensating aids, use and influence of
medication, alcohol or drugs, and incapacitation for other reasons
EXAMPLE Compensating aids: glasses, hearing aid.
4.4.5
road user appearance
position (4.4.5.1), posture (4.4.5.2), clothing and other relevant factors relating to a road user (4.4) before
a road vehicle accident (3.1)
4.4.5.1
position
where the road user (4.4) was physically situated before a road vehicle accident (3.1)
EXAMPLE Left front seat, carriageway, pavement (4.2.7).
4.4.5.2
posture
attitude of the body of the road user (4.4) before a road vehicle accident (3.1)
Note 1 to entry: Description of body action is included in this concept.
4.4.5.3
use of safety device
use, either proper or improper (misuse), of restraints and personal devices intended for accident or
injury (4.4.6) protection
4.4.5.3.1
proper use of safety device
use of a safety device as intended by the manufacturer
4.4.5.3.2
misuse of safety device
deviation from the intended use of a safety device
4.4.5.4
seat position
location of the occupant seat before a road vehicle accident (3.1)
4.4.6
injury
bodily harm to a person
Note 1 to entry: Effects of diseases are not injuries.
4.4.6.1
lesion
type of injury (4.4.6)
EXAMPLE fracture, rupture or laceration.
4.4.6.2
severity
subdivision of injuries with respect to degree of injury (4.4.6)
[13]
Note 1 to entry: See AIS 90 .
4.4.7
body region
subdivision of human body into specified areas
[14]
Note 1 to entry: See OIC 80 .
4.4.7.1
aspect
location within an organ or a body region (4.4.7)
EXAMPLE Right–left, distal–proximal.
4.4.8
treatment
medical observation or care of a person
Note 1 to entry: On-scene rescue operations are included in this concept.
4.4.8.1
hospitalization
inpatient admission of a person to a hospital for treatment (4.4.8)
4.4.9
examination level
source of injury (4.4.6) information
EXAMPLE Police, physician, victim.
12 © ISO 2020 – All rights reserved/Tous droits réservés

4.4.10
injury outcome
consequence induced by injuries sustained in a road vehicle accident (3.1)
4.4.10.1
fatality
injury outcome (4.4.10) resulting in death
Note 1 to entry: Usually an injury outcome is classified as a fatality when death occurs within a defined time period.
4.4.10.2
incapacitating injury
injury outcome (4.4.10) preventing the injured person from the normal continuation of activities he or
she was capable of performing before the injury (4.4.6) occurred
4.4.10.3
impairment
injury outcome (4.4.10) resulting in organ dysfunction
Note 1 to entry: Organ dysfunction can be a loss or abnormality of structure or function of an organ, psychological,
physiological or anatomical.
4.4.10.4
disability
injury outcome (4.4.10) resulting in individual dysfunction
Note 1 to entry: Individual dysfunction can be an impairment (4.4.10.3) of a person’s capacities or of the body as
a whole.
4.4.10.5
handicap
injury outcome (4.4.10) resulting in social dysfunction
Note 1 to entry: Social dysfunction is the total disadvantage resulting from impairment (4.4.10.3) and disability
(4.4.10.4) causing impaired performance at the cultural and social level.
4.4.11
non-injury outcome
consequence, other than injury outcome (4.4.10), induced by a road vehicle accident (3.1)
EXAMPLE Socio-economic changes, mental handicap (4.4.10.5).
Note 1 to entry: Such consequences concern a specific road user (4.4) and can be short-term or long-term.
5 Terms related to crash analysis and reconstruction
5.1
crash analysis and reconstruction
activity carried out to derive data and to increase the amount of usable data from a particular road
vehicle accident (3.1)
5.2
crash sequence
chronological sequence of object, vehicle and road user (4.4) contact during the crash phase
Note 1 to entry: See Figure 3.
Figure 3 — Sequence of accident-related events involving collision(s)
5.3
vehicle coordinate system
right-handed coordinate system with a selected origin for defining the location of points on the vehicle
Note 1 to entry: See ISO 4130.
5.4
site coordinate system
right-handed coordinate system with an arbitrarily selected origin used to define the location of points
at the scene of an accident
Note 1 to entry: The metre is the preferred unit of measurement.
5.5
impact configuration
position (4.4.5.1) and heading of each accident-involved vehicle (3.10) and road user (4.4) given in the site
coordinate system (5.4) at the initial time of impact
5.6
final configuration
position (4.4.5.1) and heading of each accident-involved vehicle (3.10) or road user (4.4) in the rest position
(4.2.20) given in the site coordinate system (5.4)
5.7
travel speed
speed of an accident-involved vehicle (3.10) before any accident-related events
Note 1 to entry: Accident-related events could be avoidance manœuvres or an unstable situation.
5.8
impact phase
time span during which there is an interaction of forces between the accident-involved vehicles (3.10)
or objects
5.9
impact velocity
velocity of the centre of gravity (CG) of an accident-involved vehicle (3.10) immediately prior to impact
5.10
intrusion velocity
velocity of occupant compartment intrusion (4.3.22) related to a defined point or axis in the occupant
compartment
Note 1 to entry: See occupant compartment intrusion (4.3.22).
14 © ISO 2020 – All rights reserved/Tous droits réservés

5.11
contact velocity
vector difference between the velocity of the struck body region (4.4.7) of a road user (4.4) and the
velocity of the vehicle part or other object it was struck by
5.12
closing velocity
vector difference between impact velocity (5.9) and velocity of the centre of gravity of a vehicle/object
struck immediately before impact
5.13
separation velocity
velocity of the centre of gravity (CG) of an accident-involved vehicle (3.10), road user (4.4) or roadside
(4.2.3) object immediately after the impact phase (5.8)
5.14
deformation energy
energy dissipated in producing the residual crush (4.3.14.3)
Note 1 to entry: The deformation energy equals:
1/2 × m × (EES)
where
m is the effective mass at impact (4.3.20.1), expressed in kilograms;
EES is the energy equivalent speed (5.15).
5.15
energy equivalent speed
EES
equivalent speed at which a particular vehicle would need to contact any fixed rigid object in order to
dissipate the deformation energy (5.14) corresponding to the observed vehicle residual crush (4.3.14.3)
Note 1 to entry: See note to 5.14.
5.16
equivalent barrier speed
EBS
barrier equivalent velocity
BEV
approximate energy-equivalent speed of a vehicle with respect to a 90° fixed and rigid barrier
Note 1 to entry: Especially when referring to tests involving other types of barrier (e.g. deformable offset
barriers), the broader concept of EES (5.15) should instead be used.
5.17
equivalent test speed
ETS
speed of a vehicle on impact against a barrier, or of a mobile barrier on impact with a vehicle, in an
equivalent crash test
Note 1 to entry: Especially when referring to tests involving other types of barrier (e.g. deformable offset
barriers), the broader concept of EES (5.15) should instead be used.
5.18
delta-v
Δv
vector difference between impact velocity (5.9) and separation velocity (5.13)
Note 1 to entry: Delta-v is calculated as:
 
Δ=vv −v
where

v is the velocity vector of CG of a vehicle before impact;

v is the velocity vector of CG of a vehicle after impact.
Note 2 to entry: Consequently, in a frontal impact Δv will be negative, i.e. directed towards the driver (4.4.1.2).
Note 3 to entry: Especially referring to event data recorders and airbag algorithm practices, any point of the
deltav time history and at any point of a vehicle might be called delta-v, but should preferably marked with an
index like e.g. Δv at 20 ms, B-pillar.
5.19
change in momentum
vector difference of the momenta (m × Δv) of a vehicle during the impact phase (5.8) related to impact
velocity (5.9) and separation velocity (5.13)
5.20
delta-t
Δt
time duration of the impact phase (5.8)
5.21
delta-s
Δs
distance covered by the CG of a vehicle during the impact phase (5.8)
5.22
crash pulse
acceleration – time history during the impact phase (5.8)
5.22.1
mean acceleration
average rate of change of velocity of the CG during the impact phase (5.8)
Note 1 to entry: The mean acceleration can be calculated with respect to Δt ( a =Δv/Δt), or Δs:
2 2
vv−
0 1
a=
2Δs
where
a
is the mean acceleration;
v is the velocity of CG of a vehicle before impact;
v is the velocity of CG of a vehicle after impact.
5.22.2
peak acceleration
highest acceleration value during the impact phase (5.8), given a specific filtering
Note 1 to entry: The type of filtering used on accelerometer data for calculation of peak acceleration should be
documented.
16 © ISO 2020 – All rights reserved/Tous droits réservés

5.22.3
time to peak acceleration
time passed from the start of the impact phase (5.8) until the peak acceleration (5.22.2) value has
been reached
5.23
DEPRECATED: point of impact
site of impact not precisely defined
5.23.1
initial point of impact
point in time and in the site coordinate system (5.4) where the vehicles or objects begin to touch or
interact without significant force
Note 1 to entry: The initial point of impact is the start of the impact phase (5.8).
5.23.2
point of maximum impact
point in time and in the site coordinate system (5.4) where the maximum forces have acted
5.23.3
non-central impact
eccentric impact
impact in which the impulse vector does not pass through the CG at the point of maximum impact (5.23.2)
Note 1 to entry: The CG can move during the impact phase (5.8).
5.24
initial impact
first impact in a road vehicle accident (3.1)
5.25
principal impact
the most severe impact in terms of energy dissipated on the vehicle
5.26
first harmful event
event producing the first occurrence of injury (4.4.6) or damage in a road vehicle accident (3.1)
Note 1 to entry: Harmful event definition is in line with ANSI D.16:2017, 2.4.1.
5.27
most harmful event
event producing the most serious occurrence of injury (4.4.6) or damage in a road vehicle accident (3.1)
Note 1 to entry: The most harmful event is evaluated for each accident-involved vehicle (3.10). If two or more
events in the crash sequence (5.2) produce equivalent injury or crush (4.3.14), the first such event shall apply.
Note 2 to entry: Harmful event definition is in line with ANSI D.16:2017, 2.4.1.
5.28
run-out trajectory
geometric description of the path of the vehicle from the point of separation to the rest position (4.2.20)
Note 1 to entry: The run-out could include a rollout (5.39) or spinout.
5.29
occupant trajectory angle
resultant angle between the vehicle X-axis (and/or Z-axis) and the direction along which an occupant
moves in relation to the vehicle’s X- and Z-axes
5.30
separation direction
direction of separation velocity (5.13) measured counter-clockwise from the X-axis of the site coordinate
system (5.4)
5.31
throw distance
distance between the initial point of impact (5.23.1) and the rest position (4.2.20) of objects or road users
(4.4) above the ground
Note 1 to entry: The throw distance includes any subsequent sliding distance on the ground.
5.32
partial ejection
ejection where a vehicle occupant’s body is partly outside the exterior periphery of the vehicle occupant
compartment
5.33
complete ejection
ejection where the whole body of a vehicle occupant is outside the exterior periphery of the vehicle
occupant compartment
5.34
skid
slide of a tire without rotation, in any direction, on a road surface
5.35
slip
wheel slip
ratio of the forward velocity of the tire at the road surface to the forward velocity at the centre of
the wheel
5.36
slip angle
angle between the X-axis of the vehicle and the direction of travel of the CG
Note 1 to entry: Either the slip angle of the tire, or the slip angle of the vehicle can be used.
5.37
sideslip
lateral/transverse movement of a vehicle with a velocity component perpendicular to the vehicle heading
5.38
yaw
angular motion around an axis parallel to the vehicle’s Z-axis
5.39
rollout
part of the runout phase in which little or no wheel slip (5.35) or sideslip (5.37) occurs, usually leading
to the rest position (4.2.20)
5.40
pitch
angular motion around an axis parallel to the vehicle’s Y-axis
5.40.1
pitch-over
event in which a vehicle pitches at least 90°
Note 1 to entry: See also definition of pitch (5.40).
18 © ISO 2020 – All rights reserved/Tous droits réservés

5.41
roll
angular motion around an axis parallel to the vehicle’s X-axis
5.41.1
rollover
event in which a vehicle rolls (5.41) at least 90°
5.42
vaulting
roll (5.41) or pitch-over (5.40.1) of a vehicle where the movement is made without ground contact
5.43
glance-off
vehicle-to-vehicle or a vehicle-to-object impact that results in significantly unequal separation velocities
Note 1 to entry: The interpreted meaning of “significantly” will depend on the purpose of the analysis.
5.44
sideswipe
glance-off (5.43) with minimal engagement where the impact force is primarily tangential to the side of
a vehicle
Note 1 to entry: A practical definition of the term can be found in SAE J224 (CDC).
5.45
endswipe
glance-off (5.43) with minimal engagement where the impact force is primarily tangential to the front
or rear end of a vehicle
Note 1 to entry: A practical definition of the term can be found in SAE J224 (CDC).
6 Terms related to aggregate data analysis and interpretation
6.1
exposure
parameter describing the dose or amount of some physically measurable parameter(s) related to an
accident or injury (4.4.6) or both
EXAMPLE Travel distance (6.3), traffic density, crash severity.
6.1.1
induced exposure
exposure (6.1) not including other data
EXAMPLE Ratios between different types of accident (paired comparisons, odds ratios).
6.2
vehicle years of service
total time of potential use for a designated group of vehicles
Note 1 to entry: The vehicle years of service can be cumulated over several years and is useful for developing
normalized accident rates. It is measured in vehicle years.
6.3
travel distance
DEPRECATED: mileage
aggregate distance of travel for vehicles or road users (4.4) for a designated group of vehicles or road users
Note 1 to entry: Travel distance is measured in kilometres.
6.4
effectiveness
efficiency
DEPRECATED: efficacy
relative reduction in injury (4.4.6) risk or fatality (4.4.10.1) risk attributable to a designated safety feature
EXAMPLE Consider a seat belt system with an effectiveness of 40 % (when used), worn at a 30 % usage rate.
The “effectiveness (as used)” will be 12 %.
Note 1 to entry: Effectiveness is often measured as a percentage and calculated as:
ff−
e= 100%
f
where
e is effectiveness, and where, for example,
f is the frequency of injury accident (3.3) without safety device, and
f is the frequency of injury accident with safety device.
Note 2 to entry: The effectiveness of safety devices such as seat belts is sometimes measured on an “as used”
basis, taking observed or expected restraint system (4.3.9) usage into account.
6.5
vehicle crashworthiness
characteristics of a vehicle that determine the degree to which occupant protection is achieved in that
vehicle in a particular collision
6.6
vehicle aggressivity
vehicle aggressiveness
characteristics of a vehicle that determine the degree to which injury (4.4.6) is inflicted upon the road
users (4.4) with which it collides in a particular crash configuration
6.7
vehicle compatibility
characteristics of a vehicle that optimally balance overall protection for all occupants and road users (4.4)
20 © ISO 2020 – All rights reserved/Tous droits réservés

Annex A
(informative)
Fundamental road terms
A.1 Comparison of standards for road designations
A comparison between different standards is shown below. Definitions are given according to ANSI D16
[11] [12]
and the Convention on road signs and signals :
Key
a
May or may not be present
Figure A.1 — Fundamental road terms
Table A.1 — Designations relative to Figure 1 according to ANSI D16, the Convention on road
signs and signals and this document
Code ANSI D16 Convention This document
on road signs
and signals
A Roadway Carriageway —
B Shoulder Edge of —
carriageway
Table A.1 (continued)
Code ANSI D16 Convention This document
on road signs
and signals
A + B Road Road —
C Roadside — Roadside
A + B + C Trafficway — —
D Median — Median
A.2 Road terms
Table A.2 is a comparison between main road terms defined by ANSI D16, the Convention on road signs
and signals and this document.
Table A.2 — Comparison of corresponding road terms according to ANSI D16, the Convention on
road signs and signals and this document
ANSI D16 Convention on Road Signs and This document
Signals
roadway carriageway
That part of a trafficway designed, The part of road normally used by
improved, and ordinarily used for vehicular traffic; a road may com-
motor vehicle travel or, where var- prise several carriageways clearly
ious classes of motor vehicles are separated from one another by, for
segregated, that part of a trafficway example, a dividing strip or a differ-
used by a particular class. ence of level.
shoulder edge of the carriageway
That part of a trafficway contiguous
The edge of the remainder of the
with the roadway for emergency
carriageway for other road-users,
use, for accommodation of stopped
also one or more sidelanes or tracks
road vehicles, and for lateral sup-
reserved for use by certain vehicles.
port of the roadway structure.
road road
That part of a trafficway which The entire surface of any way or
includes both the roadway and any street open to public traffic.
shoulder alongside the roadway.
roadside
area adjoining the outer edge of
the road
trafficway
Any land way open to the public
as a matter of right or custom for
moving persons or property from
one place to another.
median strip US
central reservation GB
median
dividing strip
area separating two roadways
lane
Any one of the longitudinal strips
into which the carriageway is divid-
ed, whether
...