ISO/TR 12204:2012

TECHNICAL ISO/TR
REPORT 12204
First edition
2012-11-15

Road vehicles — Ergonomic aspects of
transport information and control
systems — Introduction to integrating
safety critical and time critical warning
signals
Véhicules routiers — Aspects ergonomiques des systèmes
d'information et de contrôle du transport — Introduction à l'intégration
des signaux d'avertissement critiques en termes de sécurité et de
temps




Reference number
ISO/TR 12204:2012(E)
©
ISO 2012

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ISO/TR 12204:2012(E)

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ISO/TR 12204:2012(E)
Contents Page
Foreword .v
Introduction.vi
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Abbreviated terms .4
5 Warning signals and situation where a warning signal is presented .4
5.1 Classification of warning signals .4
5.1.1 Background.4
5.1.2 Criticality .5
5.1.3 Urgency .5
5.1.4 Duration of signal .6
5.1.5 Direction of hazard .6
5.2 Hazard perception by drivers.6
5.2.1 Background.6
5.2.2 Visible and detected by the driver .7
5.2.3 Visible but not detected by the driver .7
5.2.4 Not readily perceptible to the driver.7
5.3 Description of vehicle systems that signal the driver .7
5.3.1 Systems requiring time critical and safety critical response .7
5.3.2 Systems requiring time critical, but not safety critical response .8
5.3.3 Systems requiring safety critical, but not time critical response.8
5.3.4 Systems requiring neither safety critical, nor time critical response.8
5.4 Possible driver responses.8
5.4.1 Background.8
5.4.2 Preparation.9
5.4.3 Responses .9
6 Discussion of integration vs. prioritization .9
6.1 Background.9
6.2 Prioritization.10
6.3 Integration .10
6.4 Relationship of integration and prioritization.10
7 Issues for integration: Distinguishability and comprehensibility .11
7.1 Background.11
7.2 Distinguishability.11
7.3 Comprehensibility .11
8 Situations where warning integration is needed.12
8.1 Background.12
8.2 Warning signals sharing the same sensory modality .12
8.3 Warning signals in close spatial proximity.12
8.4 Warning signals with same characteristics.12
8.5 Frequent vs. infrequent warning signal presentation .13
8.6 Multiple warning signals that are presented simultaneously or in close temporal
proximity.13
9 Tools for warning signals integration .13
9.1 Background.13
9.2 Threshold adjustment.13
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ISO/TR 12204:2012(E)
9.3 Establish modes .13
9.4 Establish distinguishability .14
9.4.1 Spatial distinguishability .14
9.4.2 Temporal distinguishability .14
9.4.3 Distinguishability by other warning signal characteristics.14
9.5 Use of common warning signals to indicate different hazards from the same direction .14
10 Identification and evaluation methods .15
10.1 Background.15
10.2 Procedure to identify integration needs.15
10.3 Timely Comprehension Method .15
10.4 Appropriate Response Method .15
Annex A (informative) Procedure for assessing integration needs.16
Annex B (informative) Timely Comprehension Methodology.37
Annex C (informative) Appropriate Response Methodology.45
Bibliography .49

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ISO/TR 12204:2012(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
In exceptional circumstances, when a technical committee has collected data of a different kind from that
which is normally published as an International Standard (“state of the art”, for example), it may decide by a
simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely
informative in nature and does not have to be reviewed until the data it provides are considered to be no
longer valid or useful.
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.
ISO/TR 12204 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 13,
Ergonomics applicable to road vehicles.
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ISO/TR 12204:2012(E)
Introduction
This Technical Report supplements the information provided in ISO/TR 16352 “MMI of warning systems in
vehicles” and specifically addresses the topic of warning signal integration in automobiles.
This Technical Report contains a mixture of general guidance information where technical consensus
supports such guidance, as well as discussion of those areas where further research is required to support
technical consensus. It should be noted, however, that the general guidance contained in this Technical
Report is informative, rather than normative, in nature.
The HMI of warning interfaces for stand-alone active safety systems is not standardized. Recently,
“Guidelines on establishing requirements for higher-priority warning signals” is being developed by the
UNECE/WP29/ITS Informal Group. There are, however, many different interfaces used on production
vehicles. The integration of multiple stand-alone warning systems requires consideration of basic properties of
the interface such as modality, timing, and redundancy. This can lead to complex trade-offs for the system
designer. It may well be that over time the industry and/or governmental regulators will converge on common
specifications for warning interfaces for stand-alone warning systems.
It should also be noted that a key underlying assumption for the purposes of this Technical Report is that each
of the stand-alone warning system signals to be integrated has been previously validated in terms of
effectiveness and acceptability. Therefore, any changes to a particular warning signal that may be suggested
by evaluating the integration of multiple warning signals into a coherent HMI are intended to address an
integration issue, only, and not to compensate for any deficiency that may be present in the design of one or
more underlying stand-alone warning/systems.
Poorly integrated warning signals may not be noticed or could be misunderstood, confused, or ignored and
could potentially impair system performance causing the driver to respond too slowly, inappropriately or not at
all. Poor integration could limit the safety benefits of the warning system.
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TECHNICAL REPORT ISO/TR 12204:2012(E)

Road vehicles — Ergonomic aspects of transport information
and control systems — Introduction to integrating safety critical
and time critical warning signals
1 Scope
This Technical Report provides general, informative guidance for the integration of safety critical and time
critical warning signals (signals which, if ignored even briefly, could result in bodily harm to the occupant(s) of
the vehicle and/or to other road users) into existing in-vehicle messages presented to a driver. Integration of
non-critical signals are outside the scope of this Technical Report, except to confirm that they do not affect the
driver’s comprehension of safety and time critical signals.
This Technical Report provides:
1) possible approaches for determining if integration is necessary to mitigate the possibility that signals from
one or more vehicle system may degrade the driver's comprehension of, or response to, safety critical
warning signals from another system(s); and
2) a discussion of possible methods for assessing potential integration conflicts.
It does not provide prescriptive guidance in how to design an integrated warning HMI.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
Not applicable.
3 Terms and definitions
3.1
abstract visual signal
simple figure such as circle or square that has no clear meaning
3.2
active safety warning system
system incorporating sensors to detect potential hazards that communicate a warning signal to the driver so
that a hazard may be avoided by driver intervention
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ISO/TR 12204:2012(E)
3.3
auditory icon
auditory signal that represents an event or action without using verbal expression
NOTE This auditory signal can be a synthesized sound that gives the impression of a specific event or a recorded
sound from everyday life.
3.4
ambient noise
sensory stimulus that is not relevant to the specific task of the driver in the vehicle's environment
NOTE This can include sound emanating from inside and outside the vehicle (auditory noise), reflection of sunlight,
glare from headlights of surrounding vehicles (visual noise), and vibration from the vehicle (haptic noise).
3.5
comprehensibility
characteristic of a signal enabling the driver to understand the meaning of the signal in the context in which it
is provided
3.6
criticality level
classification of severity of the collision
3.7
distinguishability
characteristic of the warning signal to be perceived by the driver when two or more signals share the same
sensory mode, or are presented in close temporal within the driving environment
3.8
event
significant occurrence in the driving environment of a subject vehicle/driver
3.9
human machine interface
controls and displays that allow a human to interact with a manufactured device or system
3.10
integration
incorporation and organization of multiple devices or systems into a unified, coherent HMI, ensuring that all
warning signals can be understood independently of when or how they are presented (individually or
simultaneously) when present in the vehicle
3.11
priority
relative importance of two or more messages or signals
NOTE For warning signals, priority level can be obtained from criticality and urgency levels of a signal.
3.12
response time
time period from the onset of a warning signal to the point at which the driver starts to perform a vehicle
control action
EXAMPLE The time from the onset of a forward vehicle collision warning system signal to when the driver starts to
depress the brake pedal.
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ISO/TR 12204:2012(E)
3.13
safety critical signal
signal that is intended to warn a driver in time for corrective action to be taken to prevent vehicle damage or
personal injuries
NOTE There are four levels of criticality, categorized based on occupant (both in the vehicle and on the road) injury
and vehicle damage defined in ISO/TS16951. The four levels are:
⎯ Criticality level 3, severe or fatal injury to occupants;
⎯ Criticality level 2, injury or possible injury to occupants;
⎯ Criticality level 1, no injury to occupants but with damage to vehicle involved; and
⎯ Criticality level 0, neither injury to occupant nor damage to any vehicle.
“Safety critical signal” defined here pertains only to criticality levels 3 and 2.
3.14
scenario
driving events and situations experienced by a driver
3.15
signal
visual, auditory, or haptic stimulus information produced by an in-vehicle system or an on-road system for the
purposes of communicating driving-related information to the driver
NOTE Signals include both warning and non-warning signals.
3.16
symbol
visually perceptible figure used to convey information independently of language, produced by drawing,
printing, or other means.
[ISO 2575:2010, definition 3.1]
3.17
system integrator
person(s) responsible for integration of a warning device or systems in a vehicle HMI
3.18
time critical signal
signal with high urgency level that requires driver’s response to an imminent event measurable within ten
seconds
NOTE Time critical signal may or may not pertain to a warning event. There are four levels of urgency, categorized
based on how fast the driver needs to respond to the warning signal. The four levels are:
⎯ Urgency level 3, respond immediately (within zero to 3 sec);
⎯ Urgency level 2, respond within a few seconds (3 to 10 sec);
⎯ Urgency level 1, response preparations (take action or decision within 10 sec to 2 min);
⎯ Urgency level 0, information only (ISO/TS 16951).
“Time critical signal” defined here pertains only to criticality level 3 and 2.
EXAMPLE Signal that informs a driver of an unsafe closing distance to an object in the vehicle’s path which requires
braking or evasive steering less than 10 sec.
3.19
tone
simple sound or mixture of simple sounds with fixed frequency
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ISO/TR 12204:2012(E)
NOTE Tone includes continuous sound and intermittent sound.
3.20
urgency level
classification of the time within which driver action or decision has to be taken if the benefit intended by the
system is to be derived from the signal
3.21
voice message
signal with identifiable spoken terms
3.22
warning event
object, obstacle, or event in the driving environment that is likely to cause harm if ignored
3.23
warning signal
signal that is both safety critical and time critical indicating a warning event
NOTE Warning signals always pertain to risk of personal injury or death and do not include things such as navigation
instructions that might also require the driver to take an action within a set time period.
4 Abbreviated terms
ACC Adaptive cruise control system
CSW Curve speed warning system
FCW Forward collision warning
HMI Human machine interface
HUD Head up display
LCM Lane change/merging warning system
5 Warning signals and situation where a warning signal is presented
5.1 Classification of warning signals
5.1.1 Background
Signals in a vehicle may communicate with the driver through auditory, visual, or haptic modalities. The
signals that are candidates for integration can be classified in numerous ways, depending on which of their
features are the most salient for the purposes of integration. In addition to the characteristics of signals, it is
also necessary to consider the situation of the driver at the time that a given signal(s) is issued. Factors such
as visibility and range of the hazard(s), e.g. other vehicle, pedestrian, roadside object, as well as necessary
responses, influence how multiple warning signals should be presented. The performance characteristics that
should be considered when developing an integrated HMI for multiple warning systems are classified
according to the following description of warning signals and situations.
NOTE The parameters listed below are intended to identify characteristics of individual warning signals and situations
in order to facilitate the identification of potential conflicts among signals. The specific values that are identified (such as
the amount of response time available to the driver) have been taken from ISO/TS 16951.
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ISO/TR 12204:2012(E)
5.1.2 Criticality
5.1.2.1 Severe or fatal injury level warning signal
Warning systems that assist a driver in averting a collision that can damage the vehicle and possibly cause
severe or fatal injury to the occupants.
EXAMPLE Forward collision warning that assists the driver avoiding a collision with a lead vehicle at high speed.
5.1.2.2 Injury or possible injury level warning signal
Warning systems that assist a driver in averting an intermediate or low-speed collision that can damage the
vehicle and possibly risk the safety of occupants.
EXAMPLE Side collision warning signal that assists the driver avoiding a vehicle (side)-to-vehicle (side) collision at
intermediate or low speed.
5.1.2.3 No injury (vehicle damaged) level warning signal
Warning signals that assist a driver in averting a low-speed collision that can damage the vehicle and does not
risk the safety of the occupants.
EXAMPLE Back-up warning signal that assists the driver avoiding a collision with structure at low speed.
5.1.2.4 No injury (no vehicle damage) level warning signals
Warning signals that assist a driver in averting a very low-speed collision that does not damage the vehicle
and does not risk the safety of the occupants.
5.1.3 Urgency
Time within which driver action or decision has to be taken if the benefit intended by the system is to be
derived from the signal (ISO/TS 16951).
5.1.3.1 Respond immediately
Take immediate action or decision (within zero to three seconds) according to the presented warning signal.
EXAMPLE Obstacle immediately in the vehicle path. Brake immediately. Steer to avoid dangerous situations.
5.1.3.2 Respond within a few seconds
Take action or decision according to the warning signal within 3 to 10 sec.
EXAMPLE Obstacle within a few seconds in the vehicle path. Brake in a few seconds. Steer away from danger as
required.
5.1.3.3 Response preparation
Prepare to take action or decision in response to the warning signal within 10 sec to 2 min.
EXAMPLE Onset of detection of an obstacle.
5.1.3.4 Information Only
No direct action or decision required by the driver.
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ISO/TR 12204:2012(E)
EXAMPLE System on.
5.1.4 Duration of signal
5.1.4.1 Background
Another aspect of the temporal characteristics of a warning signal is the length of time that a signal is provided
to the driver after it is initially presented.
5.1.4.2 Continuous
A continuous warning signal persists until the end of the event and may provide a continuous update of the
situation.
EXAMPLE Signal that indicates the driver is too close to the lead vehicle.
5.1.4.3 Discrete
A discrete warning signal indicates the existence of an event but is independent of the duration of the event
itself.
EXAMPLE Virtual rumble strip that lasts for a predetermined period, irrespective of whether or not the vehicle returns
to the roadway.
5.1.5 Direction of hazard
5.1.5.1 Background
Hazards may arise from any direction around the vehicle. Providing an integrated warning system requires a
system integrator to consider the direction of the hazard and the likelihood that the driver has perceived it,
especially when it appears in the presence of other hazards.
5.1.5.2 Front of vehicle
Obstacles in the forward field of view of a driver may or may not be readily perceivable by the driver the
moment his or her attention is directed to the forward road scene where the hazard has been detected by a
warning system.
5.1.5.3 Side of vehicle
Obstacles to the side of a vehicle may or may not be readily perceivable by the driver the moment his or her
attention is directed to the side of the vehicle where the hazard has been detected by a warning system.
EXAMPLE Warning system detecting the presence of another vehicle in the driver's blind zone during an apparent
attempt to merge into an adjacent lane.
5.1.5.4 Rear of vehicle
Obstacles to the rear of a vehicle may or may not be readily perceivable by the driver the moment his or her
attention is directed to the rear of the vehicle where the hazard has been detected by a warning system.
5.2 Hazard perception by drivers
5.2.1 Background
Warning signals are used to direct a driver's attention to hazards in the driving environment that the driver has
apparently failed to perceive (or has yet to be perceived), or assess the situation appropriately, as indicated by
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ISO/TR 12204:2012(E)
a failure to take corrective action. The driver's failure to perceive a hazard may stem from a variety of causes,
which may in turn invoke special considerations for warning system designers and integrators.
5.2.2 Visible and detected by the driver
Events or situations the driver is readily able to see.
5.2.3 Visible but not detected by the driver
5.2.3.1 Background
Events that are not perceived by the driver, or not otherwise readily detectable from visual, haptic or audible
cues. This is a situation where warning signals are to be utilized effectively to avoid hazards.
5.2.3.2 Driver failed to look
Warning signals regarding events/situations that could be directly visible to the driver with a brief scan of the
mirrors or a glance, but have gone undetected by the driver due to failure to attend to an area where the
hazard appears.
5.2.3.3 Driver looked but did not see
Warning signals provided for readily perceptible events that the driver has failed to recognize.
5.2.4 Not readily perceptible to the driver
Warning signals associated with an event/situation that is not readily perceivable by the driver. This is a
situation where warning signals help the driver to detect hazards.
5.3 Description of vehicle systems that signal the driver
5.3.1 Systems requiring time critical and safety critical response
5.3.1.1 Active safety vehicle dynamic system
Active safety vehicle dynamic systems can stabilize the vehicle and help prevent accidents. They incorporate
sensor systems that are capable of detecting hazardous conditions of the vehicle. Various technologies are
incorporated as sensors, either individually or in combination. These include sensors within the vehicle, such
as yaw rate, wheel speed, and acceleration sensors that are designed to monitor the dynamics of the vehicle.
A signal (usually visual) is sometimes given to the driver during activation of the system
...