HD 638 S1:2001

SLOVENSKI STANDARD
01-september-2002
Road traffic signal systems
Road traffic signal systems
Straßenverkehrs-Signalanlagen
Systèmes de signaux de circulation routière
Ta slovenski standard je istoveten z: HD 638 S1:2001
ICS:
93.080.30 Cestna oprema in pomožne Road equipment and
naprave installations
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

HARMONIZATION DOCUMENT HD 638 S1
DOCUMENT D'HARMONISATION
HARMONISIERUNGSDOKUMENT January 2001
ICS 93.080.30
English version
Road traffic signal systems
Systèmes de signaux de circulation Straßenverkehrs-Signalanlagen
routière
This Harmonization Document was approved by CENELEC on 2000-04-01. CENELEC members are
bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for
implementation of this Harmonization Document on a national level.
Up-to-date lists and bibliographical references concerning such national implementation may be obtained
on application to the Central Secretariat or to any CENELEC member.
This Harmonization Document exists in three official versions (English, French, German).
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway,
Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. HD 638 S1:2001 E
Foreword
This Harmonization Document was prepared by the CENELEC Task Force BTTF 69-3 (TC 214 WG1),
Road traffic signal systems.
The text of the draft was submitted to the formal vote and was approved by CENELEC as HD 638 S1 on
2000-04-01.
The following dates were fixed:
– latest date by which the existence of the HD
has to be announced at national level (doa) 2000-10-01
– latest date by which the HD has to be implemented
at national level by publication of a harmonized
national standard or by endorsement (dop) 2001-08-01
– latest date by which the national standards conflicting
with the HD have to be withdrawn (dow) 2003-04-01
__________
- 3 - HD 638 S1:2001
Contents
Introduction. 4
1 Scope. 5
2 Normative references. 5
3 Definitions . 6
4 Electrical supply and limits . 9
5 Safety. 11
6 Testing. 19
7 Electrical interfaces. 26
8 Installation. 26
9 Maintenance . 29
10 Marking and labelling . 32
11 Classification of environmental test conditions . 33

Introduction
To satisfy the legal and regulatory requirements and specific provisions of each CENELEC country,
certain characteristics in this standard contain a range which is defined by a number of discrete classes.
The class to be used in the country will be selected by the Standards Authority of the CENELEC member
of that country from the range specified.
Thus this document contains the essential electrotechnical requirements of all CENELEC countries and
permits through the class selection procedure, countries to incorporate their own requirements.
It is believed that this first step will allow, over a period of time, a gradual alignment of Road Traffic
Signal Systems in Europe.
- 5 - HD 638 S1:2001
1 Scope
This standard specifies requirements for Road Traffic Signal Systems, including their development,
design, testing, installation and maintenance.
In particular, it forms the electrotechnical part of the following two standards issued by CEN:
EN 12368 Traffic control equipment – Signal heads
EN 12675 Traffic Signal Controllers – Functional safety requirements
Each of these standards above shall be used with this standard either singly or together to define an
operational equipment or system. This shall be achieved by using the electrotechnical methods and
testing defined in this standard.
Where Road Traffic Signal Systems are to be used with other systems e.g. public lighting or railway
signalling and communication, this standard shall comply with the other respective standard to ensure
that overall safety is not compromised.
Only permanently or temporarily installed Road Traffic Signal Systems are included in this standard.
Central office and portable signalling systems are not covered.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications.
These normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this European Standard only when incorporated in it by amendment or revision. For undated
references the latest edition of the publication referred to applies.
EN 12368 Traffic control equipment - Signal Heads
EN 12675 Traffic signal controllers – Functional safety requirements
EN 50102 1995 Degrees of protection provided by enclosures for electrical equipment
against external mechanical impacts (IK Code)
EN 50110-1 Operation of electrical installations
ENV 50129 Railway applications - Safety related electronic systems for signalling
EN 50293 Electromagnetic compatibility - Road traffic signal systems - Product
standard
EN 60529 1991 Degrees of protection provided by enclosures (IP Code)
+ corr. May 1993 (IEC 60529:1989)
EN 60598-1 Luminaires
Part 1: General requirements and tests (IEC 60598-1, mod)
EN 61008 series Electrical accessories
Residual current-operated circuit-breakers without integral overcurrent
protection for household and similar uses (RCCBs)
(IEC 61008 series, mod)
EN ISO 9001 Quality systems - Model for quality assurance in design/development,
production, installation and servicing
HD 384.2 International Electrotechnical Vocabulary
Chapter 826: Electrical installations of buildings (IEC 60050-826)
HD 384.4 series Electrical installations of buildings
Part 4: Protection for safety (IEC 60364-4 series, mod)

HD 384.5.54 1988 Electrical installations of buildings
Part 5: Selection and erection of electrical equipment
Chapter 54: Earthing arrangements and protective conductors
(IEC 364-5-54:1980, mod).
EN 60068-2-1 Environmental testing - Part 2: Tests;
Test A: Cold (IEC 60068-2-1)
EN 60068-2-2 Basic environmental testing procedures; Part 2: Tests;
Test B: Dry heat (IEC 60068-2-2 + IEC 60068-2-2A)
EN 60068-2-5 Environmental testing - Part 2: Tests;
Test Sa: Simulated solar radiation at ground level (IEC 60068-2-5)
EN 60068-2-14 Environmental testing - Part 2: Tests;
Test N: Change of temperature (IEC 60068-2-14)
EN 60068-2-30 Environmental testing - Part 2: Tests;
Tests Db and guidance: Damp heat, cyclic (12 + 12-hour cycle)
(IEC 60068-2-30)
EN 60068-2-64 Environmental testing - Part 2: Test methods - Test Fh: Vibration, broad
band random (digital control) and guidance (IEC 60068-2-64)
EN 60417 series Graphical symbols for use on equipment (IEC 60417 series)
IEC 60050-191 International Electrotechnical Vocabulary
Chapter 191: Dependability and quality of service
IEC 60536 1992 Classification of electrical and electronic equipment with regard to protection
against electric shock
3 Definitions
3.1 General
3.1.1
Road Traffic Signal Systems
include systems and devices, provided they are affiliated to them in terms of circuitry.
They may consist of the following elements which is not in itself a complete list:
Controllers
Signal heads, signalling devices and traffic signs,
e.g. signal heads for traffic signals,
acoustic signal generators,
mechanical signal generators,
traffic signs connected to the Road Traffic Signal System
Traffic sensors and detectors,
e.g. request push buttons,
vehicle detectors / Pedestrian Detectors
Monitoring equipment,
e.g. photographic monitoring devices
Equipment Enclosures
Electrical Supply
Cables
Interconnections
Supports
- 7 - HD 638 S1:2001
3.1.2
Failure Mode Analysis
a means of examining all failure modes to ensure that signal states endangering the road users and/or
risk of electrical hazard cannot occur during normal conditions of operation of a Road Traffic Signal
System or if they do occur under failure mode that they can not continue
3.1.3
Signal Safeguarding Facility
facilities intended to prevent states of signals endangering the traffic
3.1.4
monitoring element
device that signals electrical and mechanical states of equipment, preferably for signal circuits, and
which convert the obtained information in such a manner that it can be processed in signal safeguarding
facilities
3.1.5
hardware
the complete Road Traffic Signal System or a (material) part of it
3.1.6
hardware fault
failures of components and any influence that will cause the equipment to fail
NOTE  Systematic hardware faults constitute either design faults or systematic production faults.
3.1.7
software
all or part of the sequence instructions for a Road Traffic Signal System including the affiliated
documentation.
NOTE  Software is exclusively immaterial, so that it is subject to no wear or failure mechanisms. Once implemented, software cannot be
falsified on its own.
3.1.8
software error
deviation between the realised and intended functional contents of the software
NOTE  All errors in the software are systematic errors. They are caused by:
– invalid specification (incorrect formulation of intention)
– incorrect programming (incorrect translation of the specification to sequential instructions).
Apparent program falsification in memories is produced by hardware faults or failures or is caused by inadmissible
influencing.
3.2 Traffic engineering
3.2.1
controllers (traffic)
an electrical device to control signals
3.2.2
signal group
the sequence of conditions applied to a group of signal heads, which always received identical signal
light indications
3.2.3
Operating System
the principle software that allows a computer to operate. This software establishes the basic foundations,
protocols and functions that the computer can perform, including communication with internal and
external resources
3.2.4
Application Program
software that determines specific tasks that a computer can perform i.e. operate as a traffic controller.
Application software rests on and extends the capabilities of the operating system to meet customer
needs
3.2.5
Traffic Data
that data which specifies how the application program will perform in the particular circumstances of one
traffic system. This may be considered to be in 2 parts
3.2.5.1
Traffic Safety Data
is all Traffic Data stored in non-volatile memory that has a direct impact on the safety of road users
3.2.5.2
Traffic Non Safety Data
all the remainder of the data which will not cause an unacceptable danger to the road user if the data is
changed
3.2.6
Design Authority (Design Responsible)
the individual or group (organisation) responsible for the safe design and manufacturing, including the
instructions for safe use, installation and maintenance of the equipment or system
3.3 Electrotechnical
3.3.1
live part
See HD 384.2
3.3.2
enclosure (EN 50102)
a part providing protection of equipment against certain external influences and, in any direction
protection against contact
NOTE  This definition from the existing International Electrotechnical Vocabulary (HD 384.2) needs the following explanations under
the scope of this standard.
1) Enclosures provide protection of equipment against harmful effects of mechanical impacts and protection of persons and livestock
against access to hazardous parts.
2) Barriers, shapes of openings or any other means - whether attached to the enclosure or formed by the enclosed equipment -
suitable to prevent or limit the penetration of the specified test probes are considered as part of the enclosure, except when they
can be removed without the use of a tool.
3.3.3
complete protection
protection that achieves the following:
a) effective and durable prevention of contact with live parts by the attachment of obstacles at least
conforming to type of protection IP2x as defined in EN 60529;
or
b) complete enclosure of live parts by insulating material that can be removed only by destruction
(protection by insulating envelopment)
3.3.4
partial protection
protection that prevents the possibility of accidental contact by persons or by objects usually handled by
them in one of the following ways:
a) by placing live parts at a distance that the possibility of accidental contact by persons or objects
usually handled by them is excluded (protection against accidental contact by a safety clearance);
or
b) by attaching obstacles conforming at least to type of protection IP1x as defined in EN 60529
(protection against accidental contact by the attachment of obstacles)

- 9 - HD 638 S1:2001
3.3.5
reinforced insulation
See EN 60529
3.3.6
nominal voltages
See HD 384.2
3.3.7
earthed systems
See HD 384.2
3.3.8
Class 0 equipment
See IEC 60536
3.3.9
Class I equipment
See IEC 60536
3.3.10
Class II equipment
See IEC 60536
3.3.11
Class III equipment
See IEC 60536
3.3.12
safety extra-low voltage (SELV)
See IEC 60536
3.3.13
protective conductor (symbol PE)
See HD 384.2
3.3.14
earthing conductor
See HD 384.2
3.3.15
RCD
See EN 61008 and EN 61009
3.3.16
voltage dip
See IEC 60050-161
4 Electrical supply and limits
4.1 Nominal voltages
The standard nominal voltage for connection to the public supply shall be taken to be 230 V AC .
r.m.s
Other nominal voltages shall be permitted.

4.2 Operating voltage range
The system shall be classified according to its mains voltage range within which the Road Traffic Signal
System shall work as defined by EN 12675, as follows:
Class A1: nominal voltage -13%.+10%;
Class A2: 220 volts -20%.+15%.
The system shall not display signals which contravene EN 12675 when the supply voltage is outside the
above voltage ranges.
4.3 Low voltage
4.3.1 Switch off response voltage (V )
off
The system shall be classified as follows according to whether or not it automatically switches off when
the supply voltage falls below a specified value.
Class B0: no automatic switch off is required;
Class B1: automatic switch off is required at nominal voltage -20%;
Class B2: automatic switch off is required at nominal voltage -25%.
4.3.2 Auxiliary state switch response voltage (V )
aux
The auxiliary state is a state specified by the customer which will occur when normal operation is not
satisfactory due to low supply voltage or other specified conditions. This state shall be specified by
EN 12675 as:
Signals off
or
Flashing Yellow
etc.
The system shall be classified as follows according to whether or not the system automatically switches
to an auxiliary state when the supply voltage falls below a specified value (V ).
aux.
Class C0: no auxiliary state is required;
Class C1: the system switches to the auxiliary state when the supply voltage has any value between
the minimum operating voltage as specified in 4.2 and V .
off
4.3.3 Power up activation voltage
The system shall become active when the supply voltage reaches a value within its operating voltage
range. The restart procedure shall normally be automatic or in exceptional circumstances it may be by
manual or remote control. No signalling state dangerous to traffic shall be possible and the signalling
state shall conform to EN 12675.
4.4 Overvoltage
The system shall be classified as follows according to whether or not a protective device is incorporated
which cuts off the supply voltage to prevent damage. Where incorporated, the protective device shall
operate when the supply voltage is greater than the operating voltage range.
Class D0: no protective device is required;
Class D1: a protective device is required to provide protection up to 1500 V .
r.m.s
4.5 Voltage dip
The system shall be classified according to the duration of dips in supply which affect the operation. In
order to avoid undesirable reactions by the signal safeguarding facilities, the system shall operate as
shown in Table 1 according to the duration of the voltage dip below V or V . Where B0 and C0 are
off aux.
specified, V or V shall be taken as zero.
off aux
Period t is a timeperiod of a voltage dip in the supply which will not affect the normal operation of the
system.
- 11 - HD 638 S1:2001
Period t is a timeperiod of voltage dip in the supply when the system shall change to signals OFF
followed by the start up sequence.
Table 1 - Classification according to voltage dip (Values in milliseconds)
Criterion Class E1 Class E2 Class E3
Period t < 50 < 20 < 20
Period t >300 >800 >100
For Class E1, E2 or E3:
For any voltage dip in the supply between t and t the controller may remain working correctly or change
1 2
to signals OFF followed by the start up sequence.
4.6 Mains frequency
The system shall be classified as follows according to the acceptable variations in mains frequency.
Class F1: 50 Hz ±2%
Class F2: 50 Hz ±4%
Class F3: 50 Hz ±10%
Class F4: 60 Hz ±2%
4.7 Detectors
The detectors may be powered from a separate supply or from the controller. The recommended
voltages are:
The OPERATING VOLTAGE (see 4.2);
110 V AC;
24 V AC;
24 V DC;
12 V DC.
5 Safety
5.1 Electrical safety
5.1.1 General
The Road Traffic Signal System shall conform to HD 384.4. This subclause deals with the additional
requirements for Road Traffic Signal Systems.
5.1.1.1 Criteria - leakage current
5.1.1.1.1 Road Traffic Signal Systems
Class T1:
For Road Traffic Signal Systems, leakage current protection facilities conforming to HD 384.4.41 shall be
fitted. Earth leakage circuit breakers conforming to EN 61008 for nominal currents 20% greater than the
expected current and nominal leakage currents ≤ 0,3 A shall be installed.
Class T2:
No requirement for leakage current protection facilities for the whole system, however the customer may
request facilities as class T1.
5.1.1.1.2 Maintenance equipment supply
Class U0:
No requirement to provide earth leakage current protection facilities for the maintenance equipment
socket in addition to those specified above, but there may be a requirement to provide this facility when
portable tools are used.
Class U1:
Earth leakage circuit breakers conforming to EN 61008 with nominal leakage currents ≤ 0,03 A shall be
installed.
5.1.1.2 Earthing
This subclause applies to the installation or part of the installation which is class I conforming to
IEC 60536.
5.1.1.2.1 Protective earth conductor (PE)
The system shall conform to HD 384.5.54.
Protective earth conductors shall connect together all conductive parts and the PE terminals throughout
the system. They shall either be created by conductors in a cable or by separately installed wires and/or
construction parts.
In controllers the PE conductors shall be connected to the PE terminal / earth bus bar.
NOTE  Metallic bodies which, by virtue of their location or smallness, cannot be touched or are unlikely to become live shall be
designated excluded devices, i.e. they need not be connected to the PE conductor.
5.1.1.2.2 PE wiring of external equipment
NOTE 1  Examples of external equipment are poles, signal heads and detectors.
The system shall be classified according to the following methods.
Class L0:
PE wiring is not required in class II systems conforming to IEC 60536.
Class L1:
Accessible conductive parts shall be connected to the PE conductors incorporated in the cables or a
separate PE cable.
NOTE 2  Armouring of cables may also be used as PE conductors where the cable construction permits.
Class L2:
Accessible conductive parts shall be connected to a PE conductor incorporated in the cable. The signal
pole shall have an additional PE conductor in the form of a cable with a cross section of at least 10 mm
and at least 1 m longer than the cores of the cables to the distributor in the poles.
NOTE 3  Armouring of cables may also be used as PE conductors where the cable construction permits.
5.1.1.2.3 Accepted methods of earthing
Extraneous bodies shall be connected to each other by one of the following methods:
a) the connection points have been welded, reliably riveted or firmly bolted;
b) the connection points shall be established on bare metallic locations under pressure that is
maintained continuously e.g. slide-in modules.
Hinges shall have an earth bonding conductor fitted across them.
The system of earthing poles shall be classified according to the requirement for earthing and the size of
the terminal point screw for the PE conductor, as follows. The terminal point shall always be above the
ground level.
Class M1: always earthed, no screw size is specified
Class M2: earthed if required, minimum size M8
Class M3: earthed if required, minimum size M6
5.1.1.3 Enclosure
The enclosure shall provide the mechanical protection to IK07 (see EN 50102) with the following criteria:
No damage shall occur to the equipment contained within the enclosure and the equipment shall
continue to operate to it’s specification. There shall be no degradation of the IP rating of the equipment.
Class V1:
Enclosures shall provide protection to IP44. When the manual panel is open, the protection provided
shall be to IP42. When the enclosure is open the protection shall be to IP20.

- 13 - HD 638 S1:2001
Class V2:
Enclosures shall provide protection to IP54. When the manual panel is open, the protection provided
shall be to IP43. When the enclosure is open the protection shall be to IP23.
Class V3:
Enclosures shall provide protection to IP44. When the enclosure is open the protection shall be to IP21.
Class V4:
Enclosures shall provide protection to IP55. When the manual panel is open, the protection provided
shall be to IP43. When the enclosure is open the protection shall be to IP20.
5.1.1.4 Access
Covers, doors, flaps, or similar allowing access to controls, circuits or live parts when opened, shall be
capable of being opened only with the aid of a key or a tool. Keys may be specified either on a country
basis or by the customer.
5.1.1.5 Over-current protection
Supply voltages within the enclosure or external to the enclosure shall have excess current protection,
generally by means of fuses or circuit breakers in accordance with HD 384.4.
5.1.1.6 Terminations
The system shall be classified according to its access to mains terminations as follows:
Class H0: No separate access to mains terminations.
Class H1: separate access to meters or parts of a mains terminal etc.
5.1.1.7 Controller enclosure doors
The controller enclosure shall be classified according to whether or not it is fitted with a device to lock the
doors in the open position as follows:
Class J0: No open locking device provided.
Class J1: Inspection doors shall be provided with an open locking device or simple unhinging
mechanism. The doors shall not be capable of being unhinged in the closed position.
Class J2: No open locking device provided, but the purchaser may specify the device.
5.1.2 Controller Signal outputs
The controller shall provide electrical power to the signal heads. Electrical details of compatible signal
heads shall be specified by the controller manufacturer in order to ensure the safety of the system.
NOTE  The recommended voltage ranges are:
– The OPERATING VOLTAGE
– 40 V AC
– 50 V - 0 - 50 V AC
– 55 V - 0 - 55 V AC
The controller shall be classified according to the range of the current / power per signal output of the
controller, which shall include at least one or more of the following ranges:
Class K1: 0,1 A to 4 A
Class K2: 0,09 A to 2,0 A
Class K3: 0,07 A to 5 A at power factor > 0,8
Class K4: 30 VA up to 1200 VA
5.1.3 Signal heads
The signals shall use electrical power from the controller which shall be specified by the signal
manufacturer.
NOTE  The safety of the system depends on the compatibility of the signal controllers and the signal heads particularly with respect
to the signal safeguarding facilities (see 5.2.2). For example but not restricted to:
Lamps at operating mains voltage, 15 W to 200 W
Lamps at 12 W to 100 W with an associated transformer
LED signals
5.1.4 Detectors and push buttons
The general rules of this document and HD 384.4 apply. Purchasers may request for Functional Extra
Low Voltage working.
5.1.5 Interconnections
5.1.5.1 PE Terminal
The terminal points of the PE conductor on bodies shall be easily accessible and shall bear the
identification mark specified in EN 60417. They shall provide bare metallic contact and serrated washers
shall be used.
5.1.5.2 General terminations
The terminal points shall be of corrosion resisting materials.
5.1.5.3 Plugs and Sockets
Female connectors shall always be connected to the power supply and shall provide protection against
touching live parts when not interconnected.
5.1.6 Cables
5.1.6.1 PE cable dimensions
The minimum cross sections of PE conductors shall be as follows:
a) if part of a composite cable the size of the largest conductor;
b) if laid in a protected manner 2,5 mm copper;
c) if laid in an unprotected manner 4,0 mm copper.
5.1.6.2 Earth cable dimensions
The minimum cross sections of earth conductors shall be as follows:
a) if corrosion protected : 16 mm copper or galvanised steel;
b) if corrosion unprotected : 25 mm copper;
50 mm galvanised steel.
5.1.6.3 Distribution cables
Distribution cables shall be designed to work in the environment found in traffic signal systems. They
shall be of adequate cross section to withstand fault currents which may occur under fault conditions.
NOTE  This is dependent on the size of the protection device, the temperature range and the insulation material.
The rating voltage of cables carrying mains voltage shall be 1000 V minimum.
The number of cores specified for the installation will depend on the facilities required.
5.2 Traffic safety
5.2.1 General
For the present subclause concerning rules for the functional safety of Road Traffic Signal Systems the
definitions for "item" and "failure" according to IEC 60050-191 shall be applied.
Failures shall be considered at different levels of the Road Traffic Signal System. Failures considered in
EN 12675 are apparent to road users, i.e. traffic and pedestrians. In this subclause those failures of items
of the Road Traffic Signal System which may lead to the faults described in EN 12675 are considered.
This subclause defines the requirements for traffic signal safety, the testing of which is defined in
clause 6.
- 15 - HD 638 S1:2001
5.2.2 Requirements of signal intensity for safety
The signal limits for safety shall be to one of the following classes
Class AF1:
The luminous intensity of the light output on axis for signals which are required for safety to be ”ON”, e.g.
Red, shall be greater than 10 cd (as specified in EN 12368).
The luminous intensity of the light output for signals which are required for safety to be ”OFF”, e.g.
Green, shall be less than 0,05 cd (as specified in EN 12368).
The signal manufacturer shall specify the signal requirements either voltage, current or alternative
signalling system to ensure that the above limits are met. The system engineer shall ensure that the
controller shall provide an action on these limits.
Class AF2:
For signals which are required for safety to be ”ON” shall be considered to be switched on if the output
voltage is greater than 160 V or if the current is greater than 10 mA.
r.m.s
For signals which are required for safety to be ”OFF” shall be considered to be switched off if the voltage
on the output of the controller is less than 50 V .
r.m.s
Class AF3:
For signals which are required for safety to be ”ON” shall be considered to be switched on if the output
voltage is greater than 160 V and if the current is greater than 10 mA per signalhead.
r.m.s
For signals which are required for safety to be ”OFF” shall be considered to be switched off if the voltage
on the output of the controller is less than 50 V .
r.m.s
Class AF4:
For a supply at 24 V AC for signals which are required for safety to be ”ON” shall be considered to be
switched on if the output voltage is greater than 16 V or if the current is greater than 100 mA.
r.m.s
For signals which are required for safety to be ”OFF” shall be considered to be switched off if the voltage
on the output of the controller is less than 5 V .
r.m.s
Class AF5:
For signals which are required for safety to be ”ON” shall be considered to be switched "ON" if the
voltage on the output of the controller is greater than 50% of the full rated output voltage and if the
current is greater than 10 mA per signalhead.
For signals which are required for safety to be ”OFF” shall be considered to be switched off if the voltage
on the output of the controller is less than 20% of the full rated output voltage.
5.2.3 Requirements for signal states
5.2.3.1 Signal states which endanger traffic shall be prevented during operation of a Road Traffic
Signal System as described in 5.2.3.4. When a system is installed and operated within the
manufacturer’s specified limits and there are no random hardware failures or systematic failures (e.g.
software errors) the signals will conform to the requirements in EN 12675 for correct operation. It is not
allowed to operate a system outside of the specified limits.
5.2.3.2 Failures shall be primarily prevented by formal measures of quality assurance in development
and manufacturing as well as by correct installation. This shall be achieved by EN ISO 9001 or
equivalent. The occurrence of failures shall also be limited by use of reliable components, proper
operation and scheduled maintenance.
5.2.3.3 If a failure could lead to a signal state endangering the traffic as defined in EN 12675 a
functional independent safeguarding facility shall lead to a safe state of operation as defined in
EN 12675. This safeguarding facility shall become active within a time interval specified according to the
following classes:
Class AG1: 100 ms
Class AG2: 150 ms
Class AG3: 200 ms
Class AG4: 300 ms
Class AG5: 500 ms
Class AG6: 800 ms
Class AG7: 850 ms
Class AG8: 1000 ms
NOTE  This time interval is the time from the dangerous signal occurs until this state has been removed.
5.2.3.4 To ensure that the requirements of 5.2.3.1 to 5.2.3.3 are obeyed one of the following
procedures shall be carried out:
Class X1:
Both a failure mode analysis according to 5.2.4 and functional tests according to clause 6 shall be carried
out in accordance with signal states dangerous to traffic specified in EN 12675.
Examples of failures to be considered are given in ENV 50129.
Class X2:
Functional tests according to clause 6.
Subclause 5.2.4 is not mandatory.
5.2.3.5 The signal safeguarding facility shall always be active as long as the controller is powered.
5.2.3.6 The controller software consists of
operating system;
application software;
traffic safety data;
traffic non safety data.
It shall not be possible to alter or modify the operating system or the application program of the
controller, but the software may be replaced by alternative software which has been tested and approved
by the design authority.
It shall not be possible to modify the controller traffic safety data except by an authorised event.
NOTE  The modification of traffic safety relevant data by use of a handset or by data received from an external source may in certain
circumstances be classed as being authorised.
The modification of traffic non safety relevant data has no restrictions.
5.2.4 Failure consideration (Failure mode analysis)
The failure consideration shall be carried out according to the following rules. For information purposes
these rules are additionally depicted in Figure 1.
The consideration of failures shall be done starting from the highest hierarchical level in the system and
proceeding towards the lowest level. At each level the assessment shall be carried out until at the
considered level, all possible failures of the involved items fulfil the failure consideration. At that point
the analysis shall be considered to have been successful and the analysis shall end.
5.2.4.1 First Single Failure (Failure A)
The term "single failure" covers the initial failure and any further failures caused as the result of this
failure. A signal state endangering traffic (according to EN 12675) due to a "single failure" shall be
prevented.
5.2.4.1.1 If this failure could lead to a signal state endangering traffic, a functional independent
safeguarding facility shall become active within a time interval specified in 5.2.3.3. This activity of the
safeguarding facility shall initiate the failure mode as defined in EN 12675.
5.2.4.1.2 If this failure does not lead to a signal state endangering traffic, it may become apparent by
an on-line safety diagnostic check or by a scheduled manual proof test. Alternatively it may not become
apparent, see 5.2.4.2.
When the failure is detected by an on-line safety diagnostic check, it shall be disclosed within the safety
diagnostic check interval (SDCI) by stored message and it may in addition initiate an action. The action
may be a restriction of some controller functions or may initiate the failure mode.
When the failure is detected by a scheduled manual proof test, the detection shall occur within a proof
test interval (PTI) specified by the manufacturer.
The detected failure shall be repaired within an interval specified by the manufacturer.

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The above mentioned intervals shall be determined in a way, that the probability of a second failure
-5
which could cause an unsafe condition occurring within those intervals is less than 10 /year, i.e. the
occurrence of a second failure shall not be expected during those intervals.
5.2.4.2 Second Single Failure (Failure B)
If a first "single failure" is not apparent as defined in 5.2.4.1.2, the occurrence of an additional
independent "single failure" shall be considered. A signal state endangering traffic due to the
combination of both failures shall be prevented.
5.2.4.2.1 If the combination of two independent single failures could lead to a signal state endangering
traffic a functional independent safeguarding facility shall become active within a time interval specified
in 5.2.3.3. This activity of the safeguarding facility shall initiate the failure mode as defined in EN 12675.
5.2.4.2.2 If the combination of the two single failures does not lead to a signal state endangering
traffic, it shall become apparent by an on-line safety diagnostic check or by a scheduled manual proof
test. If this is not possible it is acceptable that the two faults remain and additional faults are considered
otherwise the design shall be considered as unacceptable.
When the failure combination is detected by an on-line safety diagnostic check, it shall be disclosed
within the safety diagnostic check interval (SDCI) by stored message and it may in addition initiate an
action. The action may be a restriction of some controller functions or may initiate the failure mode.
When the failure combination is detected by a scheduled manual proof test, the detection shall occur
within a proof test interval (PTI) specified by the manufacturer.
The detected failure combination shall be repaired within an interval specified by the manufacturer.
The above mentioned intervals shall be determined in a way, that the probability of any further failure
-5
which could cause an unsafe condition occurring within those intervals is less than 10 /year, i.e. the
occurrence of any further failure shall not be expected during those intervals.

Start
failure A failure B
signalization
no
dangerous to
traffic
?
yes
does
failure A
no yes
become apparent
by SDC during SDCI or
by PT during PTI
?
&
failure combination A&B
signalization
yes no
dangerous to
traffic
?
does
failure combination
signal yes
no no
safeguarding facility A&B become apparent
responded by SDC during SDCI or
by PT during PTI
?
?
yes
further
failures
yes
to be expected
during specified
intervals
Failure mode
?
no
Repair
... "OR" condition
all
no failures A and all
combinations A&B
... "AND" condition
considered &
?
SDC = on-line Safety Diagnostic Check
yes
SDCI = Safety Diagnostic Check Interval
PT = manual Proof Test
End of
Inadmissible,
PTI = Proof Test Interval
Failure analysis
Redesign
Figure 1 - Failure consideration of a Road Traffic Signal System
Protection against accidents caused by technical failures
(This should be read in conjunction with 5.2.4)

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5.2.5 Location of monitoring elements for signals
The following applies to the monitoring elements of signal circuits:
5.2.5.1 Location of monitoring elements for detection of absent signals
The system shall be classified according to the location of the monitoring elements for detection of
absent signals e.g. reds as follows:
Class N0:
No requirement for location is specified.
Class N1:
Monitoring elements shall be placed in the phase conductor of the signal circuit only if one of the
following applies:
1) the wires between controller and the signal heads pass without a distributor in the poles;
2) distributors in the poles with reinforced insulation against body contact are used;
3) a residual current detector is fitted with a trip value much less than the monitor circuit current.
Otherwise, monitoring elements shall be placed in the return conductor of the signal circuit.
If signal lamps are operated singly via transformers, the signal lamps and the transformer shall be
regarded as being one load unit. Fault recognition according to Figure 1 shall be verified for this single
load unit.
NOTE  The aim of these measures is to prevent the effects of incomplete short circuits to earth. For new Road Traffic Signal Systems,
floating operation of 230 V signal heads offers no advantages and is therefore preferably employed for the conversion of existing Road
Traffic Signal Systems if none of the other demands applicable to the monitoring elements are capable of realisation. Short to earth
monitoring is part of the signal safeguarding measures and leads to deactivation of the Road Traffic Signal System in the event of
response.
Class N2:
If the sensing elements are intended to measure current, it shall be ensured that the correct current is
measured, not a fault current.
This shall be carried out by:
either ensuring the location of the sensing element is not affected by fault currents, e.g. location in
series with the return conductor;
or
test for fault currents.
5.2.5.2 Location of monitoring elements for detection of unwanted displays
The system shall be classified according to the location of monitoring elements which are fitted for the
detection of unwanted displays e.g. greens as follows:
Class P0: No requirement for location is specified.
Class P1: The monitoring elements shall be connected in parallel with the switching elements which
switch the signals unless incorrect measurements are prevented.
NOTE  This measure should take into account the fact that unwanted displays are required to be detected at the visibility threshold and
an additional advantage is that wire breaks to the monitoring element are detected by the monitoring element.
6 Testing
6.1 General
6.1.1 Object
Clause 6 defines the Type testing methods used for checking the individual elements of the system as
listed in 3.1.1 which is required to meet this standard. It covers the environmental tests and functional
tests which are appropriate to EN 12368 and EN 12675 and it also covers the electrical and EMC tests
(EN 50293) which are required to be carried out in order to verify the requirements of this standard.
Full Type test reports shall be produced and available on demand for examination by a customer.

6.2 Organisation of testing
6.2.1 Ordering of tests
6.2.1.1 The tests are grouped into the following groups:
a) Random vibration tests; (6.3.2)
b) Impact test; (6.3.3)
c) Protection tests; (6.3.4)
d) Dry heat, cold, damp heat and solar radiation tests; (6.3.5, 6.3.6, 6.3.7, 6.3.8)
e) Electrical tests; (6.4)
f) Electrical safety tests; (6.5)
g) Traffic safety tests; (6.6)
h) Safety assessment. (6.6.1.8)
The tests shall normally be carried out in the order of the groups a) followed by b) etc. except that:
a), b), c) and d) must be carried out before e), f) g) and h);
b) followed by c) may be after d);
a) may be after b), c) and d).
The EMC tests as specified in 6.7 may move to occur before or after any of the above tests to suit the
manufacturer.
6.2.1.2 The same equipment shall pass each of the tests in turn and if any tests fails and requires
correction of the equipment all preceding tests shall be repeated unless it can be shown to the tester that
the corrective action has not nullified the action of the previous tests.
Replacement of failed fuses or lamps which are classed as spare parts shall be allowed during or after
the tests.
Tests of changes in the event of a modification to hardware or software the extent of the re-test shall be
agreed with the tester and the manufacturer.
6.2.2 Presentation of equipment
6.2.2.1 The equipment shall be supplied in working order and shall be a standard production version. It
shall include all the compulsory characteristics and incorporate any optional characteristics which are
required to be approved for sale and are necessary to carry out particular tests.
6.2.2.2 All removable modules forming the equipment under test shall be permanently marked with
type numbers and serial numbers. A list of numbers and serial numbers for all modules shall be
presented with the equipment.
6.2.2.3 The
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