ISO/TS 17426:2016

TECHNICAL ISO/TS
SPECIFICATION 17426
First edition
Intelligent transport systems —
Cooperative systems — Contextual
speeds
Systèmes intelligents de transport — Systèmes coopératifs — Vitesses
contextuelles
PROOF/ÉPREUVE
Reference number
ISO/TS 17426:2015(E)
©
ISO 2015
ISO/TS 17426:2015(E)
ISO/CEN PARALLEL PROCESSING
This final draft has been developed within the International Organization for Standardization (ISO), and pro-
cessed under the ISO-lead mode of collaboration as defined in the Vienna Agreement. The final draft was
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two-month approval vote in ISO and formal vote in CEN.
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ii © ISO 2015 – All rights reserved

ISO/TS 17426:2015(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Conformance . 2
3 Normative references . 2
4 Terms and definitions . 2
5 Symbols and abbreviated terms . 3
6 Contextual Speeds: Architecture . 4
7 Contextual speeds: Use cases . 5
7.1 General . 5
7.2 Use case 1: Provision of mandatory speed limit information into vehicle – for
driver awareness purposes . 6
7.3 Use case 2 - Provision of advisory speed information into vehicle – for driver
awareness purposes .10
8 Contextual speeds: Roles and responsibilities .14
8.1 Scenarios for contextual speeds .14
8.2 System operation roles in scenario 7 .15
8.3 Possible actors in the Contextual Speed Information Service .15
9 Contextual speeds: Characteristics.16
10 Contextual speeds: General service requirements .16
11 Contextual speeds: Communication requirements .17
11.1 General .17
11.2 General communication requirements .18
11.2.1 General.18
11.2.2 ITS-S application processes of the Contextual Speed Application .18
11.2.3 Flow types of the Contextual Speed Application .18
11.2.4 Flow Type 1 of the Contextual Speed Application .19
11.2.5 Flow Type 2 of the Contextual Speed Application .19
11.2.6 Flow Type 3 of the Contextual Speed Application .20
11.2.7 Sources and Sink ITS stations of the Flow Types .21
11.2.8 Other general communication requirements .21
11.3 Application specific data element requirements .22
Annex A (normative) Contextual speeds: IVI Profile (Definition of CSM) .23
Bibliography .28
ISO/TS 17426:2015(E)
Foreword
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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).
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any patent rights identified during the development of the document will be in the Introduction and/or
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Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information.
The committee responsible for this document is ISO/TC 204, Intelligent transport systems in collaboration
with CEN/TC 278, Road transport and traffic telematics.
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ISO/TS 17426:2015(E)
Introduction
Traditional fixed speed limits have, in general, been set as the maximum mandatory speed that a vehicle
or a category of vehicles can travel at. Such speed limits are defined by the competent authority. Some
national authorities moderate mandatory speed limits when road or environment conditions change.
When road or environmental conditions change, the decision as to the most appropriate speed a driver
or rider must travel is, in general, left up to the individual vehicle driver. With the advent of Cooperative
Intelligent Transport Systems (ITS), it has become possible to provide better guidance to vehicle drivers
on what speed they can travel at when road, traffic, or environmental conditions are less than ideal.
This function is known as Contextual Speed Information Service.
Delivering Contextual Speed information to road users can improve road safety, support traffic
management, and reduce greenhouse gas emissions.
In a Cooperative ITS environment, Contextual Speeds are context-dependent (e.g. changed due
to weather conditions), as well as time-specific and road section-specific speeds. Subject to local
regulations, they can be mandatory speed limits or advisory speeds.
All Cooperative ITS Services follow the same abstract structure of detection (of an event) including
pre-processing of the detected content, execution of the Service algorithm (processing of detected
content) and presentation or utilization of the Service result. Figure 1 summarizes and further
illustrates this process.
Content processing
Detection
Info service generation
Info service presentation
Figure 1 — General Cooperative ITS Service process (from ISO/TS 17427:2014, Figure A.6)
Based on this abstract process description, for any Cooperative ITS Service, a similar process description
applies to the Contextual Speed Information Service. Every single step in the process chain can be
executed by different actors or stakeholders. Execution of process elements by different stakeholders
results in a large number of possible potential scenarios. Additionally, the involvement of stakeholders
can be distinguished by spatial geography.
Assuming that there are two main stakeholder groups in Cooperative ITS, namely the Infrastructure
and the Vehicle, multiple combinations are possible, as every step can be delivered by a different
stakeholder group (see Figure 2).
Figure 2 — Possible scenarios — Simple
ISO/TS 17426:2015(E)
The scenarios address different combinations; the basis for every scenario is one specific combination.
This Technical Specification addresses the scenario where detection, content pre-processing, and
information service generation is the responsibility of the infrastructure stakeholder. The direct
presentation of Contextual Speed information on the driver interface of the vehicle is out of the scope
of this Technical Specification. This Technical Specification therefore addresses only part of the whole
process (Scenario 7).
Within the context of Scenario 7, this Technical Specification addresses Use Case 1 “Provision of
mandatory speed limit information into vehicle – for driver awareness purposes” and Use Case 2
“Provision of advisory speed information into vehicle – for driver awareness purposes”.
This does not preclude other Use Cases or deployment models in later Technical Specification(s).
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TECHNICAL SPECIFICATION ISO/TS 17426:2015(E)
Intelligent transport systems — Cooperative systems —
Contextual speeds
1 Scope
This Technical Specification
— specifies the Contextual Speed Information Service, namely the general requirements regarding the
provision of the Contextual Speed Information Service, the data flow supporting the service, and
the presentation of the service result,
— specifies the requirements to be fulfilled by the Contextual Speed Information Service,
— specifies the ITS Station (ITS-S) application processes of the vehicle ITS station, roadside ITS station,
central ITS station, and personal ITS station that are required to instantiate the Contextual Speed
Information Service,
— specifies sets of communication requirements and objectives (profiles) using the methods defined
in ISO 17423 to select the level of performance (best effort or real-time, etc.), confidence and security
(authentication, encryption, etc.) for each Contextual Speed Information Service communication
flow between ITS stations,
— selects relevant functions and procedures provided by the ITS station facilities layer (see
ISO 17429), and
— specifies messages, messages sets structure, content, and syntax to be used by the Contextual Speed
Information Service.
This Technical Specification considers the scenario for the transmission of Contextual Speed
information from the infrastructure/roadside to the vehicle, for onward presentation to the vehicle’s
driver. This scenario foresees that the calculation of Contextual Speed information is performed on the
Infrastructure side, not within the vehicle.
Mandatory speed limits or advisory speed recommendations are output of the Contextual Speed
Information Service which (in the scenario considered in this Technical Specification) is run by the
Road Operator in its Traffic Control Centre or comparable infrastructure (e.g. Roadside ITS Station). To
transfer this information to the vehicle (and therefore the driver) over the air (wireless communication),
defined messages are required. These messages are specified in this Technical Specification.
When Contextual Speed information arrives in the vehicle, further pre-processing might be necessary
before the Contextual Speed information, and, if available, additional explanations on speed limits
or recommendations, can be presented to the driver. This Technical Specification specifies the
requirements that need to be fulfilled when processing the messages. It does not specify how the vehicle
handles the incoming messages.
The production of information supporting this application, its qualification and its relevance are out of
the scope of this Technical Specification.
This Technical Specification addresses Use Case 1 “Provision of mandatory speed limit information into
vehicle – for driver awareness purposes” and Use Case 2 “Provision of advisory speed information into
vehicle – for driver awareness purposes”.
ISO/TS 17426:2015(E)
2 Conformance
To claim conformance to this Technical Specification, all mandatory requirements shall be fulfilled by
the implementation under test.
NOTE 1 Conformance testing can be different for different roles/actors. This Technical Specification identifies
the requirements for a number of Protocol Implementation Conformance Statements (PICS) proforma, allowing
to claim conformance to defined subsets of ISO/TS 17426 requirements.
NOTE 2 This Technical Specification adopts the ISO/IEC 9646-7 approach for conformance testing
specifications (i.e. development of PICS proforma, TSS&TP, ATS, and PIXIT).
3 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 21217, Intelligent transport systems — Communications access for land mobiles (CALM) — Architecture
ISO 24102–3, Intelligent transport systems — Communications access for land mobiles (CALM) — ITS
station management — Part 3: Service access points
ISO/TS 17419, Intelligent transport systems — Cooperative systems — Classification and management of
ITS applications in a global context
ISO/TS 17423, Intelligent transport systems — Cooperative systems — ITS application requirements and
objectives for selection of communication profiles
ISO/TS 17425, Intelligent transport systems — Cooperative ITS — Data exchange specification for in-
vehicle presentation of external road and traffic related data
ISO/TS 17427, Intelligent transport systems — Cooperative systems — Roles and responsibilities in the
context of cooperative ITS based on architecture(s) for cooperative systems
ISO/TS 18750, Intelligent transport systems — Cooperative systems — Definition of a global concept for
Local Dynamic Maps
4 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 21217, ISO 24102-3,
ISO/TS 17419, ISO/TS 17423, ISO/TS 17425, ISO/TS 17427, and the following apply.
4.1
advisory speed
speed set by an authority which it considers appropriate to the road, traffic, or environmental conditions
being experienced
4.2
advisory speed information
set of C-ITS data elements related to an advisory speed
4.3
C-ITS authority data set
set of C-ITS data elements describing policies or regulations
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ISO/TS 17426:2015(E)
4.4
contextual speed
context-dependent (e.g. weather conditions), as well as time-specific and road section-specific speed
Note 1 to entry: Subject to local regulations, a Contextual Speed may be a mandatory speed limit or an
advisory speed.
4.5
contextual speed information
set of C-ITS data elements related to a Contextual Speed
4.6
mandatory speed information
set of C-ITS data elements related to a mandatory speed limit (4.7)
4.7
mandatory speed limit
legally defined, maximum or minimum, speed limit for specific types or classes of vehicles or all vehicles
on a defined section of road
4.8
relevance zone
parts of the road network for which the contextual speed is valid
5 Symbols and abbreviated terms
ADU Application Data Unit
ATS Abstract Test Suite
BSMD Bounded Secured Managed Domain
C-ITS Cooperative ITS
CSM Contextual Speed Message
HMI Human Machine Interface
ICT Information Communications Technologies
ITS Intelligent Transport Systems
ITS-AID ITS Application Identifier
ITS-S ITS Station
ITS-SCU ITS-S Communication Unit
ITS-SU ITS-S Unit
LDM Local Dynamic Map
n.a. not applicable
OEM Original Equipment Manufacturer
PDU Protocol Data Unit
PICS Protocol Implementation Conformance Statement
PIXIT Protocol Implementation eXtra Information for Testing
ISO/TS 17426:2015(E)
TSS&TP Test Suite Structure and Test Purposes
6 Contextual Speeds: Architecture
The architecture of the ITS station (ITS-S) specified in ISO 21217 is illustrated in Figure 3.
Figure 3 — Simplified ITS-S reference architecture (from ISO 21217)
The Contextual Speed Information Service is provided to users by execution of the Contextual Speed
Application. The Contextual Speed Application is an instantiation of the Contextual Speed Information
Service that involves the association of complementary ITS-S application processes.
In order to be able to install and execute these ITS-S application processes in an ITS station unit (ITS-
SU) operated as a Bounded Secured Managed Domain (BSMD) specified in ISO 21217, registration
procedures identified in ISO/TS 17419 shall be applied.
The Contextual Speed Application requires communications between these ITS-S application
processes residing in ITS station units. Such communications include the exchange of Contextual Speed
Messages (CSM).
In order to enable communications between ITS-S application processes residing in different ITS
Station Communication Units (ITS-SCU) prior to transmission of application data units (ADUs), each
ITS-S application process has to register at the ITS-S management and present its communication
requirements as specified in ISO/TS 17423. Required values to be presented for the ITS-S application
processes of the Contextual Speed Application are specified in Clause 11.
Upon this registration and presentation of communication requirements, the ITS-S management will
identify the most appropriate communication profile for each source of data and assign a “FlowID” to it
as specified in ISO 24102-6.
Communications requires features of the ITS-S facilities layer both for transmission and for reception
of ADUs as specified in ISO/TS 17429.
The Contextual Speed Application requires that their related ITS-S application processes provide
received geo-referenced and time-stamped information to a Local Dynamic Map (LDM) specified in
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ISO/TS 17426:2015(E)
ISO/TS 18750. The LDM is the key element to enable cooperative behaviour in an ITS-SU, i.e. the sharing
of data between applications.
The Contextual Speed Application requires retrieving LDM data elements either by a subscription
mechanism or by a query mechanism.
The Contextual Speed Application is uniquely identified by the registered “ITS Application Identifier”
(ITS-AID) specified in ISO/TS 17419.
NOTE Contextual Speed Application uses predefined messages from the ITS Message Set as uniquely
identified by the registered “ITS Message Set Identifier” (ITS-MsgSetID) specified in ISO/TS 17419. The values of
ITS-AID and ITS-MsgSetID will be assigned by the respective registration authority. The numbering of messages
in this ITS Message Set is as uniquely defined for this ITS Message Set.
7 Contextual speeds: Use cases
7.1 General
The Contextual Speed Information Service is provided to users by execution of the Contextual Speed
Application. The Contextual Speed Application provides information from a sending ITS station to an
ITS station in a vehicle. The sending ITS station is typically a roadside or a central ITS station. The
ITS station in a vehicle may either be a vehicle ITS station or a personal ITS station. The information
supported by the Contextual Speed Application concerns either static or dynamic advisory speed
guidance or mandatory speed limits. This information is typically provided by road/traffic managers
or authorized service providers to drivers in order to improve the road safety, reduce environmental
impact, and enhance the traffic flow.
NOTE Traditionally, much of this information is available on fixed plate road traffic signs or variable displays
at the roadside or mounted above or to the side of specific lanes.
As an element of the Contextual Speed Information Service is the ability to transfer and use information
from an external environment into the vehicle for subsequent presentation, it is essential that the
service provides stable, robust, and reproducible results given a specified input condition especially in
respect of mandatory speed limits.
Furthermore, some basic safety and legal constraints are necessary, such that advisory speed outputs
shall never exceed the maximum mandatory speed limit (for the vehicle class, driver qualifications
and other legally enforceable conditions that may apply) for defined identifiable sections of road.
Similarly, the advisory speed shall never be less than a minimum mandatory speed limit (for legally
enforceable conditions).
Both mandatory and advisory speed outputs shall relate to defined, repeatable, resolvable locations.
Where the Contextual Speed Information Service is used to convey mandatory speed limits, the
application service provider shall ensure robust recording of mandatory speed limit information
disseminated.
NOTE Advisory speed can be provided for eco-driving (ecologic and economic) with the objective to reduce
pollution and energy consumption costs.
The use cases identified are the following:
— Use case 1: Provision of mandatory speed limit information into vehicle – for driver awareness
purposes;
— Use case 2: Provision of advisory speed information into vehicle – for driver awareness purposes.
ISO/TS 17426:2015(E)
Road side ITS station
Vehicle ITS station
Figure 4 — Display of Contextual Speed information (courtesy Renault)
7.2 Use case 1: Provision of mandatory speed limit information into vehicle – for driver
awareness purposes
Table 1 gives details of the Use case 1 for provision of mandatory speed limit information into vehicle –
for driver awareness purposes.
Table 1 — Use Case 1: Provision of mandatory speed limit information into vehicle – for driver
awareness purposes
Use case name Provision of mandatory speed limit information into vehicle – for driver awareness
purposes
Use case description This use case foresees the Contextual Speed Information Service providing information
from a sending ITS station (typically a roadside or central ITS station) to an ITS station
in a vehicle (typically a vehicle ITS station or a personal ITS station) concerning either
static or dynamic mandatory speed limits.
This information is presented through the vehicle’s machine to human interface (HMI) to
warn the vehicle’s driver if a maximum speed limit is being exceeded (with user defined
buffer) or that a minimum speed limit is not being achieved (with user defined buffer).
This information shall be provided by an OEM or Content Service Provider (see Clause 8)
as an authorized source. This source may often be road/traffic managers or authorized
service providers. The Contextual Speed information is presented to drivers in order
to improve the road safety, reduce environmental impact, and enhance the traffic flow.
Use case scope The scope of this Use Case is the definition of the exchange from an ITS station
(roadside or central ITS station) to an ITS station in a vehicle – for the provision
of information concerning mandatory speed limit(s) into the vehicle – for driver
awareness purposes.
It does not include the exchanges of data between the sending ITS station and any
other source systems, or vice versa; the mechanism for production of the Contex-
tual Speed Message; or any actions taken by the vehicle’s systems on receipt of the
Contextual Speed Message.
Target system release Cooperative ITS – Infrastructure-to-Vehicle applications
a
Aftermarket stakeholders are included.
b
Quality assurance of the base speed limit data are vital to the correct performance of this application. Quality assurance
procedures for this data are outside the scope of this Technical Specification.
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ISO/TS 17426:2015(E)
Table 1 (continued)
Use case name Provision of mandatory speed limit information into vehicle – for driver awareness
purposes
Generality/abstraction High-level abstract
level
a
Use case stakeholders — Road administrations
— Police and enforcement administrations
— Automotive manufacturers and their supply chain
— Radio spectrum regulators
— Broadcast/RF industry
— Drivers
— Manufacturers of roadside and central station equipment
— Other authorized government departments, agencies or agents
— Road operators and traffic managers
Use case goal To correctly provide suitable contextual information on mandatory speed limits.
Use case assumptions — Methods for ensuring the accuracy of the context for mandatory speed limit
information can be ensured. Measures of accuracy include timeliness, representa-
tion of physical relevance of speed limit information, applicability to vehicle type/
class, value of the speed limit.
— Data exchange between the sending ITS station (typically a roadside/central ITS
station) and the ITS station in the target vehicle(s) is successfully completed in a
timely manner.
— The positional relevance of a speed limit on creation suitably maps to the vehi-
cles cognisant of position to exceed defined quality requirements.
— Suitable fail-safe mechanisms will be put in place of areas of non-reception of
information.
Use case technology Data exchange between the sending ITS station and the ITS station in the vehicle is
restrictions successfully completed in a timely manner.
Relationships to other Linked to other Contextual Speed Information Service use cases
use case(s)
a
Aftermarket stakeholders are included.
b
Quality assurance of the base speed limit data are vital to the correct performance of this application. Quality assurance
procedures for this data are outside the scope of this Technical Specification.
ISO/TS 17426:2015(E)
Table 1 (continued)
Use case name Provision of mandatory speed limit information into vehicle – for driver awareness
purposes
Actors for this use case As indicated in Clause 8, the actors relevant for this use case are:
For content provision:
— Content Service Provider
For service provision:
— Application Service Provider
For presentation provision:
— ICT service provider
These actor roles may be met by one or a combination of organizational entities, e.g.
commercial service providers, road operators, etc.
Use Case 1 actors
Content provision
Gather
content
Authorized content
Service provision
service provider
Run
algorithms
Application
service provider
Deliver
CSM
Focus of this
Technical
Speciication
Presentation provision
Receive and
analyze
ICT service provider
Present
Using the service
React to
presentation
Driver
Use case triggers None – foreseen as a high-periodicity broadcast or unicast from the sending ITS
station (roadside or central ITS stations) of Contextual Speed information
Use case pre-conditions — Availability of suitable quality speed limit information
— Availability of means of communication between the sending ITS station and the
ITS station in the target vehicle
— Availability of sending ITS station(s) and an ITS station in the target vehicle
a
Aftermarket stakeholders are included.
b
Quality assurance of the base speed limit data are vital to the correct performance of this application. Quality assurance
procedures for this data are outside the scope of this Technical Specification.
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ISO/TS 17426:2015(E)
Table 1 (continued)
Use case name Provision of mandatory speed limit information into vehicle – for driver awareness
purposes
Use case steps a) Gather Content – As part of the Content Provision sub-role (see Clause 8),
information on mandatory maximum and, if present, minimum speed limits shall
be collected from available sources. In the case of fixed speed limits, such sources
could include road databases. In the case of dynamic speed limits other infrastruc-
ture sensor data and vehicle, probe data may be used to determine and validate the
current dynamic mandatory speed limit. Such dynamic speed limits may reflect
traffic conditions, weather conditions, ambient lighting conditions, road surface
conditions, and environmental conditions.
This step is outside the scope of this Technical Specification.
b) Run Algorithms – As part of the Service provision sub-role (see Clause 8),
analyses are undertaken to identify the appropriate content to be distributed. For
example, if different environmental and traffic conditions dedicate several distinct
mandatory maximum speed limits for a specific class of vehicle and driver, the algo-
rithms shall be used to select the lowest mandatory maximum speed limit applica-
ble for distribution. The algorithms shall also validate that a dynamic mandatory
maximum speed limit or environmental or traffic condition mandatory maximum
speed limit shall not exceed the static mandatory maximum speed limit for the rele-
vant location and vehicle class and driver categorizations. These are subject to local
regulations that are applicable. Similar analyses shall be performed for mandatory
minimum speed limits, if required.
This step is outside the scope of this Technical Specification.
c) Deliver Contextual Speed Message(s) (CSM) – As part of the Service provision
sub-role (see Clause 8) relevant mandatory speed limit information is prepared for
distribution using Contextual Speed Messages. The period of validity of this infor-
mation shall be included. The Deliver Contextual Speed Message process may be
carried out by the roadside ITS station, central ITS station, or a service provider.
d) Receive and Analyse – As part of the Presentation Provision sub-role (see
Clause 8), the vehicle processing unit processes the received Contextual Speed Mes-
sage. The appropriateness of the message’s validity, relevance to the vehicle’s type/
class shall be confirmed. The form of alarm to be raised shall be assessed.
e) Present – As part of the Presentation Provision sub-role (see Clause 8), the Vehi-
cle’s HMI Unit shall allocate the form of HMI interaction on the basis of the form of
alarm raised. Visual and audible warnings may be presented as appropriate.
The functionality of the vehicle’s HMI Unit is outside the scope of this Technical
Specification.
f) React to presentation – A non-system response to information presentation by
the driver.
This step is outside the scope of this Technical Specification.
Use case acceptance cri- — The system reliably delivers to the interface of the Vehicle’s HMI Unit the
b
teria intended Contextual Speed information to or above a prescribed quality level in
cases where radio communications coverage is available.
— The system correctly handles information provision in cases where expired
information is received or the vehicle moves beyond the defined relevance zone of
the Contextual Speed Information received.
a
Aftermarket stakeholders are included.
b
Quality assurance of the base speed limit data are vital to the correct performance of this application. Quality assurance
procedures for this data are outside the scope of this Technical Specification.
ISO/TS 17426:2015(E)
Table 1 (continued)
Use case name Provision of mandatory speed limit information into vehicle – for driver awareness
purposes
Use case business rules The Contextual Speed Information Service, as supported by Content Provision and
Service provision (see Clause 8), shall provide no more than one mandatory maximum
speed limit for each defined location (for specified classes or vehicles or all classes and
other legal conditions) applicable for a specified period of time. Any later publication
of similar information, as indicated by the information timestamp, will be considered
to supersede the original publication.
Similarly, the Contextual Speed Information Service, as supported by Content Provi-
sion and Service provision shall provide up to one mandatory minimum speed limit
for each defined location (for specified classes of vehicles or all classes and other legal
conditions) applicable for a specified period of time. Any later publication of similar
information, as indicated by the information timestamp, will be considered to super-
sede the original publication.
Some basic safety and legal constraints are necessary. For mandatory speed limits,
the actor supplying Content Provision shall take necessary measures to ensure the
accuracy of information provided, including, where possible, measures to ensure
consistency of information.
Mandatory speed outputs shall relate to defined, repeatable, resolvable locations.
a
Aftermarket stakeholders are included.
b
Quality assurance of the base speed limit data are vital to the correct performance of this application. Quality assurance
procedures for this data are outside the scope of this Technical Specification.
7.3 Use case 2 - Provision of advisory speed information into vehicle – for driver
awareness purposes
Table 2 gives details of the use case 2 for provision of advisory speed information into vehicle – for
driver awareness purposes.
Table 2 — Use Case 2: Provision of advisory speed information into vehicle – for driver
awareness purposes
Use case name Provision of advisory speed information into vehicle – for driver awareness purposes
Use case description This use case foresees the Contextual Speed Information Service providing information
from a sending ITS station (typically a roadside or central ITS station) to an ITS station
in a vehicle (typically a vehicle ITS station or a personal ITS station) concerning advi-
sory speed information. This information is presented via the vehicle’s HMI to advise
the vehicle’s driver of the vehicle’s speed relative to the advisory speed.
This information is provided by an OEM or Content Service Provider (see Clause 8) as
an authorized source. This source may often be road/traffic managers or authorized
service providers. This advisory speed information is intended to provide driver with
informed contextual information that is not mandatory in nature.
The Contextual Speed Information is presented to drivers in order to improve the road
safety, reduce environmental impact, and enhance the traffic flow.
Use case scope The scope of this Use Case is the definition of the exchange from the sending ITS sta-
tion (roadside or central ITS station) to the ITS station in the target vehicle for the
provision of information concerning advisory speed information into the vehicle – for
driver awareness purposes.
It does not include the exchanges of data between the sending ITS station and any other
source systems, or vice versa; the mechanism for production of the Contextual Speed
Message; or any actions taken by the vehicle’s systems on receipt of the Contextual
Speed Message.
Target system release Cooperative ITS – Infrastructure-to-vehicle applications
a
Aftermarket stakeholders are included.
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ISO/TS 17426:2015(E)
Table 2 (continued)
Use case name Provision of advisory speed information into vehicle – for driver awareness purposes
Generality/abstraction High-level abstract
level
a
Use case stakeholders — Road administrations
— Police and enforcement administrations
— Automotive manufacturers and their supply chain
— Radio spectrum regulators
— Broadcast/RF industry
— Drivers
— Manufacturers of roadside and central station equipment
— Road operators and traffic managers
Use case goal To correctly provide suitable contextual information on advisory speeds.
Use case assumptions — Methods for ensuring the accuracy of the context for advisory speed information
can be ensured. Measures of accuracy include timeliness, representation of physical
relevance of speed limit information, applicability to vehicle type/class, value of the
advisory speed given.
— Data exchange between the sending ITS station (typically a roadside/central ITS
station) and the ITS station in the target vehicle(s) is successfully completed in a
timely manner.
— The positional relevance of an advisory speed on creation suitably maps to the
vehicles cognisant of position to exceed defined quality requirements.
— Suitable fail-safe mechanisms will be put in place of areas of non-reception of
information.
Use case technology Data exchange between the sending ITS station and the ITS station in the target vehicle
restrictions is successfully completed in a timely manner.
Relationships to other Linked to other Contextual Speed Information Service use cases
use case(s)
a
Aftermarket stakeholders are included.
ISO/TS 17426:2015(E)
Table 2 (continued)
Use case name Provision of advisory speed information into vehicle – for driver awareness purposes
Actors for this use case As indicated in Clause 8, the actors relevant for this use case are the following:
For content provision:
— Content Service Provider
For service provision:
— Application Service Provider
For presentation provision:
— ICT service provider
These actor roles may be met by one or a combination of organizational entities, e.g.
commercial service providers, road operators, etc.
Use Case 2 actors
Content provision
Gather
content
Service provision
Registered content
service provider
Run
algorithms
Application
service provider
Deliver
CSM
Focus of this
Technical
Presentation provision
Speciication
Receive and
analyze
ICT service provider
Present
Using the service
React to
presentation
Driver
Use case triggers None – foreseen as a high-periodicity broadcast or unicast from the sending ITS
station (roadside/central ITS stations) of Contextual Speed information.
Use case pre-conditions — Availability of suitable quality advisory speed information.
— Availability of means of communication between the sending ITS station and the
ITS station in the target vehicle
— Availability of sending ITS station(s) and an ITS station in the target vehicle
a
Aftermarket stakeholders are included.
12 PROOF/ÉPREUVE © ISO 2015 – All rights reserved

ISO/TS 17426:2015(E)
Table 2 (continued)
Use case name Provision of advisory speed information into vehicle – for driver awareness purposes
Use case steps a) Gather Content – As part of the Content Provision sub-role (see Clause 8), information
on advisory speed information shall be collected from available sources – this may
include relevant contextual information (e.g. environment conditions, traffic conditions)
including information from infrastructure sensors and vehicle probe. Such advisory
speed information may reflect traffic conditions, weather conditions, ambient lighting
conditions, road surface conditions, and environmental conditions.
This step is outside the scope of this Technical Specification.
b) Run Algorithms – As part of the Service provision sub-role (see Clause 8), analyses
are undertaken to identify the appropriate content to be distributed. For example, if
different environmental and traffic conditions dedicate several distinct sets of advi-
sory speed information, the algorithms shall be used to select the most appropriate
for distribution. The algorithms shall also validate that advisory speed information
does not conflict with mandatory speed limits for the relevant location and vehicle
class and driver categorisations.
This step is outside the scope of this Technical Specification.
c) Deliver Contextual Speed Message(s) (CSM) – As part of the Service provision sub-
role (see Clause 8), relevant advisory speed information is prepared for distribution
using Contextual Speed Messages. The period of validity of this information shall be
included. The Deliver Contextual Speed Message process may be carried out by the
roadside ITS station, central ITS station or a service provider.
d) Receive
...