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Файл:Архитектура интеллектуальных транспортных систем = Intelligent Transport Systems’ Architecture. Учебное пособие
.pdf
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ITS standards cover a very broad range of ITS technologies, systems,
services and products – ranging from map databases to vehicle control
systems. Standards also have a vital part to play in the context of:
ITS human factors;
electronic payment and tolling;
traffic control;
vehicle control.
ITS communications standards were initially designed to enable
connectivity between vehicles and fixed infrastructure. (This included: wide
area communications protocols – such as the CALM (Communications Access
for Land Vehicles) suite of standards developed by the International Standards
Organisation (ISO) – which allow vehicles to maintain connectivity across
a variety of communications technologies dedicated short range technologies
optimised for applications such as Electronic Toll Collection (ETC).
More recently, a focus on safety-related communications has led to the
extension of this standards work in two areas of communication:
vehicle to infrastructure (V2I);
vehicle to vehicle (V2V).
These standards are needed for the deployment of cooperative systems
which depend on highly reliable, very low latency communication interactions
(time delay) between vehicles and the roadside. For example – vehicle to
roadside communications used in applications to assist in collision avoidance
and traffic flow optimization.
As vehicle connectivity has increased, the ITS standards community has
recognized the need for standardized interfaces and interactions between the
vehicle and:
the Internet of Things (IoT) – including nomadic devices such as
smartphones and tablet computers;
emergency and disaster management support services;
security and traffic control frameworks.
An early priority for standardization in ITS was the exchange of data
between traffic management centers and roadside infrastructure.
In the USA, a standards suite for road network operators and traffic
authorities is the National Transportation Communications ITS Protocol
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(NTCIP). It has been updated continuously since its development in 1997.
Its standards aim to facilitate data transfer:
between traffic management centers and roadside equipment (for
example, between traffic controllers and dynamic message signs)
between control centers the European DATEX (Data Exchange)
standard was originally created as a traffic and travel data exchange
mechanism for traffic control and information centers – but has evolved
(DATEX II) to support applications requiring access to dynamic traffic and
travel information. (See Other Monitoring Sources – Data Exchange)
A new set of standards which enable data transfer to and from connected
vehicles and devices is being developed through a number of coordinated
international efforts. (See New Forms of Mobility) For example:
the Basic Safety Message/Cooperative Awareness Message – allows
connected vehicles to share information in support of safety applications
vehicle probe data is used for a variety of applications including
crowd-sourcing of transport network information during disaster situations
2.2. Applying standards
The process of implementing standards within a road network operation
must be approached systematically:
Step 1 – Identify – where standards should be used. It is preferable to
use standardized systems wherever possible – but it may not be feasible to
standardize every aspect of every system, for a variety of practical reasons
such as cost, availability of appropriate solutions,
Step 2 – Determine – whether appropriate standards and examples of
practice already exist. Standards development is expensive – and substantial
efficiencies may be gained by learning from existing practice,
Step 3 – Assess – vendor offerings to determine standards compliance.
System architecture can be used to identify where standards are needed –
now and in the future. System architecture is a conceptual framework that
shows how different components in a system should fit together. It also shows
the key processes which require a standardized interface – especially for
communications and data exchange. The figure below illustrates this.
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The ITS architecture provides the context for standards development by
defining the different subsystems and the data that has to flow between them.
The architecture can also help identify whether the various standards should
be local, regional, national, or international. This will depend on the relevant
interfaces and an analysis of operational needs, user requirements and
hardware/software specifications.
Once the need for a standard has been identified, it is important to
determine whether such a standard already exists or must be developed. Many
ITS standards have already been written – and additional standards
development is underway in a broad range of organizations worldwide.
Research of existing standards work identifies existing standards and
standards in the making. The websites of the major standards organizations
provide an initial set of sources to investigate.
Many major standards have significant user communities that can assist
new users. The relevant national or regional ITS organization will have
suitable contacts. Practitioners who have already implemented ITS standards
in the field are often happy to share valuable lessons learned. Many standards
development organizations have resources to help connect new users to
sources of help and standards training.
The standards required may not exist. If this is the case, it is important
to assess the costs and benefits of embarking on a standards development
exercise with the appropriate standards development body. For a rapidly
developing field such as ITS, the timing of standard setting is particularly
important. Premature standards setting risk stifling innovation.
Once standards are established, consideration needs to be given to how
existing systems can migrate to the new standards over a reasonable period of
time. Users who have already invested in systems are reluctant to switch to
new standards before they have achieved a reasonable return on their
investment. Public and private organizations need to work together to promote
standards that:
benefit ITS products and services for the users;
reduce prices;
help deliver an integrated transport system that appears seamless to
the traveler.
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A number of important ITS standards are, and will probably continue to
be, uncertain moving targets. This makes planning for ITS standards adoption
and application rather tricky. Questions arise, such as:
how do I begin an ITS deployment when different vendors offer
products of different standards – none of which have been widely adopted?
should I postpone an ITS deployment indefinitely until consensus
standards are firmly established? If so – do I miss out on the benefits of early
ITS applications, that are badly needed?
There are no definite answers to these questions, but it may help to:
develop a plan, don’t let it happen by default – plan a clear strategy
that enables you to be proactive and to make informed decisions on new
standards;
review the current status of ITS standards development – review
standards development activities at all levels – and understand the background
behind conflicting standards in case you have to choose between them;
use your ITS architecture, if one exists, to identify the need for
standards – identify critical interfaces in the architecture to help prioritize the
importance of standards;
consider the implications of applying existing standards – assess the
costs and availability of products and services that meet your goals;
define an action plan for developing or migrating to standards of
importance to you – get involved in the standard development process;
if no standards exist, develop your own regional technology
cooperation agreements – consider collaboration with relevant agencies to
help you to get services started;
set up a mechanism for progressing ad-hoc standards to regional,
national, or international level as required – establish a mechanism for
cooperating with others involved in ITS deployments, to develop and agree
more widely accepted standards;
define and establish testing and certification procedures – incorporate
these formal procedures in procurement documentation to ensure that
suppliers understand how the deliverables will be tested to assess compliance
with the standard.
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2.3. Standards organizations
Standards are created at the international, regional and national levels.
Stakeholders meet under the umbrella of dedicated standards bodies or
organizations. Groups of committed individuals participate with the support
of their companies or governments – in Working Groups that follow a formal
process of development, review and ratification:
development of the text of a Standard is by consensus of the
stakeholders involved – ratification is subject to voting at national and
international level;
development of a full formal standard usually takes at least three
years, although useful results are often available well before the final
publication date.
Private companies, especially those whose business is globally oriented,
may be interested in consensus standards and harmonization of global
standards – to secure economies of scale in manufacturing and marketing.
These standards also reduce their risk of investing in new products and
services that may have limited market potential or could soon become
obsolete.
In some cases, private companies may not be interested in participating
in consensus standards setting. Companies in dominant market positions may
be reluctant to move away from the de-facto standards of their own products
– unless they are convinced that a new consensus standards will help them
access a much larger market. In situations, where the social and economic
benefit of having standards is high, a government initiative may be needed to
secure their realization.
Coordinated standards development is primarily handled by two types
of organizations:
formally accredited standards bodies;
unofficial industry consortia.
An industry consortium may form around a specific industry need for
a standard – where the participants feel that they want to work more quickly
and informally than is possible in an accredited group.
Standards developed in consortia may be submitted to an accredited
body for formal standardization. Standards developed by an individual country
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or region may become part of a more broadly harmonized approach – and
contribute to regional or international standards setting. Some countries
require adherence to standards if they have been formally approved by specific
international bodies.
ITS standards have for decades been the subject of active international
discussion and cooperation in organizations such as the International
Standards Organization (ISO) and the European Committee for Normalization
(CEN). Multiple stakeholders – governments, standards development
organizations, and commercial entities – must reconcile their various
objectives, approaches and timescales, to achieve the benefits of working
together in this way.
Intergovernmental agreements have been signed between the EU, Japan,
Korea and the USA to further advance cooperation between standards
developers in these regions. One body arising from these agreements is the
EU-US Standards Harmonization Working Group, which has developed an
action plan and other working groups to discuss:
previously agreed joint harmonization activity;
lessons learned;
gap analyses.
Many other industrialized countries have also been active in
coordinating their own ITS standards with international standardization
activities.
A number of organizations are engaged in setting standards at various
levels around the world. In many cases, regional standards work contributes
to international and global standard setting. A selection of the most significant
standards bodies is below:
ISO: The International Standards Organization (ISO) has reached
broad agreement on a classification of ITS services drawing on experience
from the European Union, Japan, the United States, and elsewhere in
18 Working Groups within ISO Technical Committee 204.
The ISO TC 204 overview can be found on the main ISO website. The
working TC204 website is: http://www.itsa.org/industryforums/isotc204.
UNITED NATIONS ECE: United Nations ECE (Economic
Commission for Europe) World Forum. The UN ECE has working parties
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engaged in a variety of ITS areas – from driver distraction to lane departure
warning systems (See http://www.unece.org/trans/theme_its.html).
CEN/CENELEC: ITU is the United Nations’ specialized agency for
information and communication technologies. ITU undertakes ITS standards
work in its radio communications division in Working Party 5A’s activity –
Collaboration on ITS Communication Standards. This group is focused on
establishing a globally harmonized set of ITS communication standards. (See
http://www.itu.int/en/ITU-T/extcoop/cits/Pages/default.aspx)
EUROPEAN COMMITTEE FOR STANDARDISATION (CEN)
CEN deals with European Standards in all domains except for electrotechnical and telecommunications matters which are handled by CENELEC
and ETSI.
CEN Technical Committee TC 278 on Road Transport and Traffic
Telematics (established in 1991) is most involved with ITS – including those
elements that need technical harmonization for intermodal operation with
other modes of transport. CEN/TC 278 cooperates with the ITS committee of
the International Standards Organization (ISO/TC 204). Cooperation is
promoted by allocating a leading role – either to ISO or CEN – for each
Working Group:
a full list of the ITS Standards under development at CEN is at
http://www.cen.eu
the website of CEN/TC 278 is at http://www.itsstandards.eu
ETSI: European Telecommunications Standards Institute (ETSI). ETSI
is a membership-based organization that produces globally-applicable
standards for Information and Communications Technologies (ICT). ITS
service provision relies on communications, especially the more advanced
services, making ITS an area of strategic relevance to ETSI – and one where
ETSI leadership is required. (See http://portal.etsi.org/its/).
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3. ITS ARCHITECTURE EMPLOYMENT
3.1. Reasons for creating. Benefits and risks
Within any single country or region, there are likely to be large
differences between the set of ITS services useful for big cities and for rural
areas. Many ITS applications (such as navigation and location based services)
are market driven. In road network operations there are always key stakeholder
groups, public authorities and private sector organizations with a part to play
(for example - in motorway network management, traffic control and toll road
operations). Each has different organizational areas of competence or
responsibility (such as road safety, public transport, fleet logistics, policing
and public security). Each has its own policy goals (fig. 3.1). Alongside there
are the wider community objectives of improving road safety, transport
efficiency and environmental quality. The process of stakeholder consultation
is intended to take account of the bigger picture – to identify what ITS services
are viable and how they should be implemented. This is outlined in the
diagram below, which shows that the first step is to define the policy goals,
and then identify the services that will support these goals. Stakeholders
nominate the ITS services that will run either fully or partially within their
own domains. These are then amalgamated to provide a set of services that
have been jointly selected by all stakeholders.
Fig. 3.1. Expression of Policy Goals
in ITS Service Selection
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The process of getting stakeholders involved should start by asking them
to describe in their own words the services that they want the ITS deployment
to include. In discussion these descriptions can then be modified so that they
will support the policy goals. It can be very beneficial if this is done through
a "stakeholder conference" so that the various groups can meet each other,
discuss the options and understand each other's requirements. Often this will
lead to the realization that some of the services can be enhanced by exchanging
data or information between different stakeholders.
For example, the highway network operators may be planning to deploy
ITS for electronic tolling and automatic incident detection. This functionality
can be adapted to give high-quality traffic and traveler information, with pointto-point journey times. An alliance between the network operators, toll road
companies and the information service providers is needed to make this
happen. The consortium will need to agree joint use of the ITS infrastructure,
protocols for information exchange, and the data and information that they
will use. All can be included in a common ITS architecture which serves the
needs of all the partners.
Another example might involve the motorway network operators
considering the use of ramp metering to maintain smooth traffic flow. An
undesirable side effect can be long queues of vehicles that spill out onto the
surrounding roads causing gridlock. Measures are needed to ensure that this
does not happen. There may also be pressure to prioritize buses and coaches
and other high-occupancy vehicles waiting on the ramp. The two network
operators - for the motorways and the surrounding roads – need to design their
traffic management policies and ITS deployments to minimize the conflict.
This might involve some form of demand management with measures to
encourage modal shift.
These examples emphasize the value of taking a broad view of the ITS
deployment rather than each agency or organization working in isolation.
Collaborative working early on - to define the full scope of ITS deployment means that changes can be made at relatively low cost before systems are
designed and equipment has been purchased.
The benefits of creating and using ITS architectures depend on the
different perspectives that stakeholders have: road network operators,
transport service providers, suppliers.
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Road network operators. The beneficiaries of ITS may be road
authorities, road operating companies – who can benefit from ITS
architectures in various ways:
through technology independence with easier planning for long term
investment and how future upgrades can be made;
by creating an open market for components, communications and
systems from a choice of suppliers based on the use of publicly available
standards;
lower costs through more open competition amongst ITS equipment
and service suppliers and communications providers.
Transport service providers. Organizations that are concerned with the
mobility of people and the movement of freight include national and local
authorities and fleet operators concerned with intermodal transport – for whom
ITS architectures provide the following benefits:
a planned approach to the deployment of ITS services (such as travel
and journey planning, vehicle fleet tracking, load monitoring, or secure
parking for trucks);
the use of compatible equipment with the same components and
interfaces being used elsewhere to benefit from interoperability, data re-use
and avoiding redundant investment;
the potential to integrate one service with another in a seamless and
logical way.
Suppliers may be component suppliers, communications providers or
system integrators – for whom ITS architecture provides the following
benefits:
lower risk for investments in system, component and communications
developments consistent with the common approach provided by the
architecture;
the possibility of larger more profitable production runs arising from
the use of "open systems" and publicly available standards - which can enlarge
the market place;
greater opportunities for small and medium enterprises to participate
in the supply chain by providing specialized components.
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