ISO 22951:2009

INTERNATIONAL ISO
STANDARD 22951
First edition
2009-01-15
Data dictionary and message sets for
preemption and prioritization signal
systems for emergency and public
transport vehicles (PRESTO)
Dictionnaire de données et ensembles de messages pour la préemption
et la priorisation des systèmes de signaux pour les véhicules d'urgence
et de transport public (PRESTO)

Reference number
©
ISO 2009
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©  ISO 2009
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ii © ISO 2009 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions. 2
4 Symbols and abbreviated terms . 3
5 Data dictionary and message sets for PRESTO. 3
5.1 Data dictionary. 3
5.2 Message sets. 4
Annex A (informative) The concept of PRESTO. 5
Annex B (informative) PRESTO architecture. 7
Annex C (normative) PRESTO requirements list . 17
Annex D (informative) Needs for standardization. 43
Annex E (informative) Background of constructing PRESTO system architecture (SA) . 44
Annex F (informative) Practical examples of PRESTO. 47
Bibliography . 50

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.
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 22951 was prepared by Technical Committee ISO/TC 204, Intelligent transport systems.

iv © ISO 2009 – All rights reserved

Introduction
It is very important that police cars, fire engines, and other emergency vehicles arrive at the scene to which
they are dispatched as soon as possible in order to improve crime prevention rate, lifesaving rate etc.
Therefore, various countries are using, or developing, preemption signal-systems to support the smooth
travelling of such vehicles. In addition, some countries use these priority signal-controls for buses and other
public transport vehicles to provide punctual and more convenient service. This International Standard
standardizes communication messages in these preemption signal-systems for emergency and public
transport vehicles, aiming to promote system introduction through developing a common infrastructure.

INTERNATIONAL STANDARD ISO 22951:2009(E)

Data dictionary and message sets for preemption and
prioritization signal systems for emergency and public
transport vehicles (PRESTO)
1 Scope
This International Standard relates to systems that use priority signal control functions to help emergency
vehicles operate. This type of system, as shown in Figure 1, is composed of a traffic management centre,
in-vehicle units, roadside communication units, and roadside units. Public transport vehicles such as buses
are also targeted to receive priority signal control service.
The scope of standardization includes message sets and data dictionary related to the communications
as follows:
⎯ between a roadside communication unit and each in-vehicle unit,
⎯ between a roadside communication unit and other roadside units,
⎯ between in-vehicle units and roadside units.
This International Standard concerns only information related to priority signal control and does not deal with
information provision such as that of the situations at scenes. Since it is necessary to handle public transport
vehicles in accordance with the conditions of individual cities and regions, the section in the messages and
the data dictionary that are concerned with priority signal control for the vehicles are treated as an option.
Furthermore, the standardization does not depend on the type of communication medium used.

Figure 1 —Scope of standardization work
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.
ISO 14817, Transport information and control systems — Requirements for an ITS/TICS central Data Registry
and ITS/TICS Data Dictionaries
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14817 and the following apply.
3.1
antenna
roadside equipment that communicates with the roadside units such as signal controllers and the in-vehicle
units using radio signals
3.2
beacon
roadside equipment that communicates with the roadside units such as the signal controllers and the
in-vehicle units
3.3
data dictionary
listing of data elements (and their characteristics) that meets the information and functional needs of a system
3.4
data element
atomic element of information
NOTE A data element is a syntactically formal representation of some information of interest (such as a fact,
proposition, observation, etc.) about some entity of interest (e.g. a person, place, process, property, object, concept,
association, state, event).
3.5
in-vehicle unit
in-vehicle equipment that transmits/receives information to/from the roadside communication units and, in
some cases, outputs information, for example, on its screen
3.6
message sets
set of basic messages that are normally used in business-oriented applications
3.7
roadside communication unit
roadside equipment that communicates with the in-vehicle units and the roadside units, e.g. beacons and
antennas
3.8
roadside unit
roadside equipment that controls signals and provides information, e.g. the signal controllers and the
information board controllers
3.9
signal controller
roadside equipment that controls the lighting timings of traffic lights
2 © ISO 2009 – All rights reserved

3.10
traffic management centre
central system that controls the functions of traffic data collection, signal control, and information service
based on collected data, etc.
3.11
vehicle ID
identification number used for the identification of emergency and/or public transport vehicles
4 Symbols and abbreviated terms
PRESTO data dictionary and message sets for preemption and prioritization signal systems for emergency
and public transport vehicles
5 Data dictionary and message sets for PRESTO
Tables 1 and 2 give the list of data dictionary and message sets within the scope of the standardization, in-line
with the data concept specified in ISO 14817. Further details are given in Annex C.
5.1 Data dictionary
Table 1 — Data dictionary within the scope of the standardization
Data concept ASN.1 object identifier ASN.1 name Descriptive name
type
Data element {iso standard presto concepts dec 1 10} PSC.authority-classification PSC.authorityClassification
concept
Data element {iso standard presto concepts de 1 20} PSC.vehicle-code PSC.vehicleCode
{iso standard presto concepts de 1 30} PSC-transport-mode PSC.transportMode
{iso standard presto concepts de 1 40} PSC-priority-signal-request- PSC.prioritySignalRequestFlag
flag
{iso standard presto concepts de 1 50} PSC-request-intersection id PSCrequestIntersectionID
{iso standard presto concepts de 1 60} PSC-direction-at-intersection PSC.directionAtIntersection
{iso standard presto concepts de 1 70} PSC-spot-id PSC.spotID
{iso standard presto concepts de 1 80} PSC-spot-passing-time PSC.spotPassingTime
{iso standard presto concepts de 1 90} PSC-vehicle-speed PSC.vehicleSpeed
{iso standard presto concepts de 1 100} PSC-vehicle-acceleration PSC.vehicleAcceleration
{iso standard presto concepts de 1 110} PSC-travel-distance PSC.travelDistance
{iso standard presto concepts de 1 120} PSC-transmission-time PSC.transmissionTime
Data frame {iso standard presto concepts df 1 130} PscVehicleID PscVehicleID:frame
{iso standard presto concepts df 1 140} PscPrioritySignalRequest PscPrioritySignalRequest:frame
{iso standard presto concepts df 1 150} PscVehicleCurrentLocation PscVehicleCurrentLocation:frame
{iso standard presto concepts df 1 160} PsctravelInformation PsctravelInformation:frame
{iso standard presto concepts df 1 170} PscSpotLocation PscSpotLocation:frame
{iso standard presto concepts df 1 180} PscSpotPassingPoint PscSpotPassingPoint:frame
5.2 Message sets
Table 2 — Messages sets within the scope of the standardization
Data concept ASN.1 object identifier ASN.1 name Descriptive name
type
Message {iso standard presto concepts PscVehicleInformation PscVehicleInformation:message
mes 1 190}
{iso standard presto concepts PscVehicleData PscVehicleData:message
mes 1 200}
{iso standard pi 11} PiSchedAdherenceOffSched PiSchedAdherenceOffSched:message

4 © ISO 2009 – All rights reserved

Annex A
(informative)
The concept of PRESTO
A.1 Purpose
PRESTO allows emergency vehicles such as police cars, fire engines and so forth to speedily and accurately
respond to emergencies by carrying out traffic signal control with the highest priority and guiding optimal
routes for these vehicles. In addition, this system draws the attention of general vehicles and pedestrians by
indicating the approach of emergency vehicles on message boards. This system carries out priority signal
control for public transport vehicles such as buses and trams. By providing travelling support to emergency
vehicles and public transport vehicles in this way, the system intends to achieve the realization of the following
effects.
a) Reduction in the response time of emergency vehicles:
⎯ early resolution of accidents and improvement of arrest rates;
⎯ support for speedy rescue activity and improvement of lifesaving rates.
b) Reduction of the number of traffic accidents associated with en-route emergency vehicles.
c) Improvement of convenience of public transport vehicles such as buses and trams by securing the
regular time operation of them.
A.2 Basic function
This system has the functions of
⎯ priority signal control,
⎯ route guidance, and
⎯ safety support.
The priority signal control function includes macro control func
...