ISO/TS 15624:2001

TECHNICAL ISO/TS
SPECIFICATION 15624
First edition
2001-01-15
Transport information and control
systems — Traffic Impediment Warning
Systems (TIWS) — System requirements
Systèmes de commande et d'information des transports — Systèmes
d'avertissement des obstacles au trafic (TIWS) — Exigences des systèmes
Reference number
©
ISO 2001
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 � CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2001 – All rights reserved

Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Terms and definitions .1
3 Specifications and requirements .2
3.1 General specifications .2
3.2 Classifications.3
3.3 Objects constituting traffic impediments and detection coverage .3
3.4 Types of sensors .4
3.5 Provision of information .4
3.6 Range of information provision to drivers.6
3.7 CCTV camera installation interval.8
4 System testing method .8
4.1 System performance test.8
4.2 System function test .8
Annex A (informative) Incidents of traffic impediment events .9
Annex B (informative) Issues to be addressed and not addressed.12
Annex C (informative) Place for introducing a system.13
Annex D (informative) Specific example of CCTV camera monitoring range .15
Annex E (informative) Symbols .16
Annex F (informative) Example for providing contents of information.17
Annex G (informative) Specific example of variable message sign installation interval.18
Annex H (informative) Specific example of system reaction time .22
Annex I (informative) Camera installation interval.24
Annex J (informative) System testing method .27
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 3.
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 other circumstances, particularly when there is an urgent market requirement for such documents, a technical
committee may decide to publish other types of normative document:
� an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in an
ISO working group and is accepted for publication if it is approved by more than 50 % of the members of the
parent committee casting a vote;
� an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting a
vote.
An ISO/PAS or ISO/TS is reviewed every three years with a view to deciding whether it can be transformed into an
International Standard.
Attention is drawn to the possibility that some of the elements of this Technical Specification may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TS 15624 was prepared by Technical Committee ISO/TC 204, Transport information and control systems.
Annexes A to J of this Technical Specification are for information only.
iv © ISO 2001 – All rights reserved

Introduction
Once an accident occurs on a highway, the accident and congestion and other hazardous conditions may result in
blocking of the lanes. This often leads to a situation where the safety of the traffic flow behind the accident cannot
be guaranteed. Conventionally, it could take more than ten minutes before the occurrence of an accident is known,
since accidents are generally reported by emergency telephones installed along the road. In the case of minor
accidents, drivers usually drive away without reporting the incident. Detection, therefore, is very difficult, and there
are cases where damaged facilities often obstruct traffic flow.
The main system function of a Traffic Impediment Warning System (TIWS) is to secure a smooth and safe flow of
traffic subsequent to an accident, and can be achieved by: quick detection of an accident, rapid processing of the
initial activities surrounding the accident and removal of impediments, dissipating traffic congestion at an early
stage, and providing information to following vehicles.
The goal of TIWS is a partial automation of the traffic impediment information collection and provision, and the
reduction of the workload of the driver with the aim to support and relieve the driver and the traffic system operator
in a convenient manner.
This Technical Specification may be used as a system level standard by other standards, which extends the TIWS
to a more detailed standard e.g. for specific sensor concepts or higher level of functionality. So, issues like specific
requirements for the sensor function and performance or communication links for cooperative solutions will not be
considered in this document.
TECHNICAL SPECIFICATION ISO/TS 15624:2001(E)
Transport information and control systems — Traffic Impediment
Warning Systems (TIWS) — System requirements
1 Scope
This Technical Specification specifies system requirements for Traffic Impediment Warning Systems (TIWS). The
purposes of the warning system are that information collected by the infrastructure is automatically and quickly
provided to vehicles and reported to the traffic system operator, so vehicles can avoid secondary accidents. A
major function of the system is to save lives by speedier rescue activities and, a quicker clearing up of accident-
caused congestion. This Technical Specification focuses on closed circuit television (CCTV) cameras as the
sensors, to detect traffic impediments using image processing and variable message signs as the communication
method to provide information to drivers.
2 Terms and definitions
For the purposes of this Technical Specification, the following terms and definitions apply.
2.1
Traffic Impediment Warning Systems
TIWS
system that automatically detects traffic impediments by employing sensors, reports occurrences of accidents to a
traffic system operator, and provides information on the presence of traffic impediments to following vehicles before
the cause is visible to them
NOTE See annex A.
2.2
stopped vehicles
vehicle that has stopped in a traffic lane or on the shoulder of the roadway
2.3
slow moving vehicles
vehicle travelling at or below “A” km/h within a traffic flow
NOTE The value for “A” is to be determined according to the road configuration and speed limit.
2.4
judgement distance
distance travelled by a vehicle until the driver judges what action is to be taken after having received information
about a traffic impediment
2.5
reaction distance
distance travelled by a vehicle from the time the driver judged what action to take until the time the brake is applied
after having been notified of a traffic impediment
2.6
braking distance
distance the vehicle needs in order to stop after the brakes have been applied
2.7
camera blind spot range
distance from the location where a camera is installed to the beginning of the area over which the camera is able to
monitor traffic impediments
NOTE The camera is unable to monitor traffic impediments in this blind area.
2.8
out-of-sight range
distance from the point where a variable message sign becomes no longer readable to the place where the
variable message sign is located
2.9
average spacing
average distance between the front of one vehicle and another in a continuous traffic flow
NOTE This parameter is inversely proportional to the density of traffic.
3 Specifications and requirements
3.1 General specifications
The system configuration should be in accordance with Figure 1.
a
The information collection subsystems consist of equipment to detect traffic impediments by various sensors installed on, or
alongside, a road. This Techical Specification focuses on the detection of traffic impediments from image processing by using
CCTV cameras serving as sensors to automatically detect traffic impediments.
b
The processing and judgement subsystem processes the information detected from a camera, and/or a sequence of
cameras, and determines the occurrence of traffic impediments.
c
The monitoring, operating and recording subsystem notifies the traffic system operator using an alarm or another method
when a traffic impediment is detected. The subsystem, using monitor TV, allows the operator to confirm both the situation and
the location of the impediment. The operator can then change the information provided to drivers as necessary, record the
situation with a VCR, or take action.
d
The notification subsystem provides information about the traffic impediments to drivers using variable message signs and
other means. Alternatively, it can forcibly close roads or prohibit traffic through certain roads.
Figure 1 — System configuration
2 © ISO 2001 – All rights reserved

3.2 Classifications
Table 1 presents a conceptual basis of the system. The table indicates that secondary accidents can be avoided
and drivers protected in the future because of the speedy detection and quick provision of information concerning
traffic impediments. Current standardization subjects are those indicated by “X” in the table.
NOTE The detection of congestion is not within the range of the systems addressed in this Technical Specification. TIWS
should detect stopped vehicles and/or slow moving vehicles at the tail of a congestion queue.
3.3 Objects constituting traffic impediments and detection coverage
3.3.1 Detection objects
3.3.1.1 Level 1: Stopped vehicles and slow moving vehicles, excluding motorcycles
3.3.1.2 Level 2: Level 1 + change in the movement of vehicles performed to avoid some obstacle or
hazardous condition that is present
3.3.1.3 Level 3: Level 2 + mo
...